Patent Application
20240067774
This disclosure generally relates to the field of high-performance, conjugated polymers and synthesis processes thereof.
Conjugated polymers are useful materials in various types of organic electronic devices, such as organic photovoltaics (OPVs) (Lu, L, et al., “Recent Advances in Bulk Heterojunction Polymer Solar Cells”, Chem. Rev., 115 (23): 12666-12731 (2015)), organic light-emitting diodes (OLEDs) (Salehi, A., et al., “Recent Advances in OLED Optical Design”, Adv. Funct. Mater., 29 (15): 1808803 (2019)), or electrochromics (Li, X., et al., “Solution-Processable Electrochromic Materials and Devices: Roadblocks and Strategies Towards Large-Scale Applications”, J. Mater. Chem., 7 (41): 12761-12789 (2019)), but one limitation to their utilization in these applications is the difficult and potentially complex nature of their synthesis. Typically, the synthesis of high performance conjugated polymers requires numerous synthetic steps, including air and moisture-free environments or cryogenic conditions, harsh/toxic reagents, and rigorous purifications during the preparation of their monomeric building blocks (Osedach, T. P., et al., “Effect of Synthetic Accessibility on the Commercial Viability of Organic Photovoltaics”, Energy Environ. Sci., 6(3): 711-718 (2013); Po, R., et al., “‘All That Glisters Is Not Gold’: An Analysis of the Synthetic Complexity of Efficient Polymer Donors for Polymer Solar Cells”, Macromolecules, 48 (3): 453-461 (2015); Li, X., et al., “Simplified Synthetic Routes for Low Cost and High Photovoltaic Performance N-Type Organic Semiconductor Acceptors”, Nat. Commun., 10(1): 519 (2019)).
Attempts to simplify synthesis have been made. Po et al. (2015) defined the synthetic complexity of a polymer as being dependent on five parameters, including number of synthetic steps (NSS), the reciprocal yield of monomers (RY), the number of operations required for purification of monomers (NUO), the number of column chromatography purifications (NCC), and the number of hazardous materials used (NHC) (Po, R., et al., “‘All That Glisters Is Not Gold’: An Analysis of the Synthetic Complexity of Efficient Polymer Donors for Polymer Solar Cells”, Macromolecules, 48 (3): 453-461 (2015)). Synthetic simplicity can be comparatively defined where a more synthetically simple polymer will have a lower number associated with it based on Po et al.'s calculations. While this approach has become a useful method for estimating synthetic complexity, McCulloch and coworkers suggest that there are too many inconsistencies in reported synthetic methods, as well as discrepancies in hazard definitions. Thus, they developed the scalability factor (SF), where the NSS and RY of the synthetic route are the main factors influencing these benchmark calculations (Moser, M., et al., “Challenges to the Success of Commercial Organic Photovoltaic Products”, Adv. Energy Mater, 11(18): 2100056 (2021)). Regardless of the approach used to assess the synthetic complexity of conjugated materials, the emphasis on reducing the number of synthetic steps while using starting materials “that could be found in the market in quantities sufficient to produce hundreds of kilograms of polymers” (Min, J., et al., “Evaluation of Electron Donor Materials for Solution-Processed Organic Solar Cells via a Novel Figure of Merit”, Adv. Energy Mater., 7 (18): 1700465 (2017)) provides motivation to explore new structural design motifs with simple chemistries.
Therefore, there exists a need for accessing conjugated polymers suitable for applications ranging from organic photovoltaics to bioelectronics through simple and safe synthetic protocols.
It is to be understood that this summary is not an extensive overview of the disclosure. This summary is example and not restrictive and it is intended to neither identify key or critical elements of the disclosure nor delineate the scope thereof. The sole purpose of this summary is to explain and exemplify certain concepts of the disclosure as an introduction to the following complete and extensive detailed description. Citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention.
The present disclosure relates to a polymeric composition for use in organic electronics. The polymeric composition can be used in photovoltaics and electrochromism. The polymeric composition includes but is not limited to a copolymer with a first pyrrolopyrrole-based monomer and a second, electroactive monomer. The first monomer includes pyrrolo[3,2-b]pyrrole (H2DPP). The second monomer includes dioxythiophene-based monomers, such as 3,4-propylenedioxythiophene (ProDOT).
The present disclosure relates to methods including synthetic schemes that comprise low synthetic complexity and reduced toxicities associated with various reagents and pathways.
The features and components of the following figures are illustrated to emphasize the general principles of the present disclosure. Corresponding features and components throughout the figures can be designated by matching reference characters for the sake of consistency and clarity.
The present disclosure can be understood more readily by reference to the following detailed description, examples, drawings, and claims, and their previous and following description. However, before the present compositions, systems, and/or methods are disclosed and described, it is to be understood that this disclosure is not limited to the specific devices, systems, and/or methods disclosed unless otherwise specified, as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.
It should be appreciated that this disclosure is not limited to the compositions and methods described herein. It is also to be understood that the terminology used herein is for the purpose of describing certain embodiments only, and is not intended to be limiting, since the scope of the present disclosure will be limited only by the appended claims.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any compositions, methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All publications mentioned are incorporated herein by reference in their entirety.
Unless defined otherwise, all composition percentage values used herein are given in terms of weight percentage.
The use of the terms “a,” “an,” “the,” and similar referents in the context of describing the presently claimed invention (especially in the context of the claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context.
Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein.
Use of the term “about” is intended to describe values either above or below the stated value in a range of approx. +/−10%; in other embodiments the values may range in value either above or below the stated value in a range of approx. +/−5%; in other embodiments the values may range in value either above or below the stated value in a range of approx. +/−2%; in other embodiments the values may range in value either above or below the stated value in a range of approx. +/−1%. The preceding ranges are intended to be made clear by context, and no further limitation is implied. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or example language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
As used herein, the term “alkyl” refers to an unsubstituted or substituted linear or branched alkyl group containing the indicated number of carbon atoms. If no number is indicated, then alkyl (optionally including any substituents on alkyl) may contain 1 to 16 carbon atoms. Preferably, the alkyl group contains 1 to 10 carbon atoms, alternatively 1 to 7 carbon atoms, or alternatively 1 to 4 carbon atoms. Examples of alkyl include methyl, ethyl, propyl, isopropyl, butyl, iso-, sec- and tert-butyl, pentyl, hexyl, heptyl, 3-ethylbutyl, and the like. Examples of substituents on alkyl include 1, 2, or 3 groups independently selected from hydroxy, amino, amido, oxa, carboxy, alkyl carboxy, carbonyl, alkoxy, amido, carbamate, carbonate, halogen, phenyl, benzyl, thiol, and combinations thereof. “Alkylene” means a divalent alkyl group, such as —CH2-, —CH2CH2-, —CH2CH2CH2-, —CH2CH(CH3)CH2-, and —CH2CH2CH2CH2-.
“Haloalkyl” refers to an alkyl group as defined above substituted with one or more halogen atoms, where each halogen is independently F, Cl, Br or I. A preferred halogen is F. Preferred haloalkyl groups contain 1-6 carbons, more preferably 1-4 carbons, and still more preferably 1-2 carbons. “Haloalkyl” includes perhaloalkyl groups, such as —CF3- or —CF2CF3-. “Haloalkylene” means a divalent haloalkyl group, such as —CH2CF2-.
The terms “halogen” or “halo” indicate fluorine, chlorine, bromine, and iodine.
“Cycloalkyl” refers to an unsubstituted or substituted cyclic hydrocarbon containing the indicated number of ring carbon atoms. If no number is indicated, then cycloalkyl may contain 3 to 12 ring carbon atoms. Preferred are C3-C8 cycloalkyl groups, C3-C7 cycloalkyl, more preferably C4-C7 cycloalkyl, and still more preferably C5-C6 cycloalkyl. Examples of cycloalkyl include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl. Examples of substituents on cycloalkyl include 1, 2, or 3 groups independently selected from alkyl, hydroxy, amino, amido, oxa, carbonyl, alkoxy, amido, carbamate, carbonate, halo, phenyl, benzyl, and combinations thereof. “Cycloalkylene” means a divalent cycloalkyl group, such as 1,2-cyclohexylene, 1,3-cyclohexylene, or 1,4-cyclohexylene.
“Heterocycloalkyl” refers to a cycloalkyl ring or ring system as defined above in which at least one ring carbon has been replaced with a heteroatom selected from nitrogen, oxygen, and sulfur. The heterocycloalkyl ring is optionally fused to or otherwise attached to other heterocycloalkyl rings and/or non-aromatic hydrocarbon rings and/or phenyl rings. Preferred heterocycloalkyl groups have from 5 to 7 members. More preferred heterocycloalkyl groups have 5 or 6 members. Heterocycloalkylene means a divalent heterocycloalkyl group.
“Aryl” refers to an unsubstituted or substituted aromatic hydrocarbon ring system containing at least one aromatic ring. The aryl group contains the indicated number of ring carbon atoms. If no number is indicated, then aryl may contain 6 to 14 ring carbon atoms. The aromatic ring may optionally be fused or otherwise attached to other aromatic hydrocarbon rings or non-aromatic hydrocarbon rings. Examples of aryl groups include phenyl, naphthyl, and biphenyl. Preferred examples of aryl groups include phenyl. Examples of substituents on aryl include 1, 2, or 3 groups independently selected from alkyl, hydroxy, amino, amido, oxa, carboxy, alkyl carboxy, carbonyl, alkoxy, amido, carbamate, carbonate, halo, phenyl, benzyl, and combinations thereof. “Arylene” means a divalent aryl group, for example 1,2-phenylene, 1,3-phenylene, or 1,4-phenylene.
“Heteroaryl” refers to an aryl ring or ring system, as defined above, in which at least one ring carbon atom has been replaced with a heteroatom selected from nitrogen, oxygen, and sulfur. The heteroaryl ring may be fused or otherwise attached to one or more heteroaryl rings, aromatic or nonaromatic hydrocarbon rings or heterocycloalkyl rings. Examples of heteroaryl groups include pyridyl, furyl, and thienyl. “Heteroarylene” means a divalent heteroaryl group.
“Alkoxy” refers to an alkyl group attached to the parent molecular moiety through an oxygen bridge. Examples of alkoxy groups include, for instance, methoxy, ethoxy, propoxy and isopropoxy. “Aryloxy” refers to an aryl group attached to a parent molecular moiety through an oxygen bridge. Examples include phenoxy. “Cyclic alkoxy” means a cycloalkyl group attached to the parent moiety through an oxygen bridge.
“Alkylamine” refers to an alkyl group attached to the parent molecular moiety through an —NH bridge. Alkyleneamine means a divalent alkylamine group, such as —CH2CH2NH—.
“Ester” refers to a class of organic compounds having the general formula RCOOR′, wherein R and R′ are any organic combining groups. R and R′ may be selected from functional groups comprising alkyls, substituted alkyls, alkylene, haloalkyls, cycloalkyls, heterocyloalkyls, aryls, heteroaryls, alkoxys, cycloalkoxys, alkylamines, siloxanyls, silyls, alkyleneoxys, oxaalkylenes, and the like. Definitions for the above mentioned functional groups are provided herein.
As used herein, “esterification” refers to a reaction producing an ester. The reaction often involves an alcohol and a Bronsted acid (such as a carboxylic acid, sulfuric acid, or phosphoric acid). Furthermore, the term “transesterification” refers to the reaction of an alcohol molecule and a pre-existing ester molecule react to form a new ester. In some aspects, transesterification can be mediated by other compounds, such as carbonyldiimidazole.
“Siloxanyl” refers to a structure having at least one Si—O—Si bond. Thus, for example, siloxanyl group means a group having at least one Si—O—Si group (i.e. a siloxane group), and siloxanyl compound means a compound having at least one Si—O—Si group. “Siloxanyl” encompasses monomeric (e.g., Si—O—Si) as well as oligomeric/polymeric structures (e.g., [Si—O]n-, where n is 2 or more). Each silicon atom in the siloxanyl group is substituted with independently selected RA groups (where RA is as defined in formula A options (b)-(i)) to complete their valence.
“Silyl” refers to a structure of formula R3Si— and “siloxy” refers to a structure of formula R3Si—O—, where each R in silyl or siloxy is independently selected from trimethylsiloxy, C1-C8 alkyl (preferably C1-C3 alkyl, more preferably ethyl or methyl), and C3-C8 cycloalkyl.
“Alkyleneoxy” refers to groups of the general formula -(alkylene-O)p- or —(O-alkylene)p-, wherein alkylene is as defined above, and p is from 1 to 200, or from 1 to 100, or from 1 to 50, or from 1 to 25, or from 1 to 20, or from 1 to 10, wherein each alkylene is independently optionally substituted with one or more groups independently selected from hydroxyl, halo (e.g., fluoro), amino, amido, ether, carbonyl, carboxyl, and combinations thereof. If p is greater than 1, then each alkylene may be the same or different and the alkyleneoxy may be in block or random configuration. When alkyleneoxy forms a terminal group in a molecule, the terminal end of the alkyleneoxy may, for instance, be a hydroxy or alkoxy (e.g., HO—[CH2CH2O]p- or CH3O—[CH2CH2O]p-). Examples of alkyleneoxy include polymethyleneoxy, polyethyleneoxy, polypropyleneoxy, polybutyleneoxy, and poly(ethyleneoxy-co-propyleneoxy).
“Oxaalkylene” refers to an alkylene group as defined above where one or more non-adjacent CH2 groups have been substituted with an oxygen atom, such as —CH2CH2OCH(CH3)CH2-. “Thiaalkylene” refers to an alkylene group as defined above where one or more non-adjacent CH2 groups have been substituted with a sulfur atom, such as CH2CH2SCH(CH3)CH2-.
The term “linking group” refers to a moiety that links the polymerizable group to the parent molecule. The linking group may be any moiety that does not undesirably interfere with the polymerization of the compound of which it is a part. For instance, the linking group may be a bond, or it may comprise one or more alkylene, haloalkylene, amide, amine, alkyleneamine, carbamate, carboxylate (—CO2-), disulfide, arylene, heteroarylene, cycloalkylene, heterocycloalkylene, alkyleneoxy, oxaalkylene, thiaalkylene, haloalkyleneoxy (alkyleneoxy substituted with one or more halo groups, e.g., —OCF2-, —CF2CF2-, —CF2CH2-), siloxanyl, alkylenesiloxanyl, thiol, or combinations thereof. The linking group may optionally be substituted with 1 or more substituent groups. Suitable substituent groups may include those independently selected from alkyl, halo (e.g., fluoro), hydroxyl, HO-alkyleneoxy, CH3O-alkyleneoxy, siloxanyl, siloxy, siloxy-alkyleneoxy-, siloxy-alkylene-alkyleneoxy- (where more than one alkyleneoxy groups may be present and wherein each methylene in alkylene and alkyleneoxy is independently optionally substituted with hydroxyl), ether, amine, carbonyl, carbamate, and combinations thereof. The linking group may also be substituted with a polymerizable group, such as (meth)acrylate (in addition to the polymerizable group to which the linking group is linked).
Preferred linking groups include C1-C8 alkylene (preferably C2-C6 alkylene) and C1-C8 oxaalkylene (preferably C2-C6 oxaalkylene), each of which is optionally substituted with 1 or 2 groups independently selected from hydroxyl and siloxy. Preferred linking groups also include carboxylate, amide, C1-C8 alkylene-carboxylate-C1-C8 alkylene, or C1-C8 alkylene-amide-C1-C8 alkylene.
As used herein, “pyrrole” refers to a heterocyclic compound (e.g. C4H5N) that has a ring comprising four carbon atoms and one nitrogen atom, polymerizes readily in air, and is the parent compound of many biologically important substances (such as bile pigments, porphyrins, and chlorophyll). The term pyrrole used herein refers to pyrrole (C5H5N), derivatives of pyrrole (e.g., indole), substituted pyrroles, as well as metal pyrrolide compounds.
When the linking group is comprised of combinations of moieties as described above (e.g., alkylene and cycloalkylene), the moieties may be present in any order. For instance, if in Formula E below, L is indicated as being -alkylene-cycloalkylene-, then Rg-L may be either Rg-alkylene-cycloalkylene-, or Rg-cycloalkylene-alkylene-. Notwithstanding this, the listing order represents the preferred order in which the moieties appear in the compound starting from the terminal polymerizable group (Rg) to which the linking group is attached. For example, if in Formula E, L and L2 are indicated as both being alkylene-cycloalkylene, then Rg-L is preferably Rg-alkylene-cycloalkylene- and -L2-Rg is preferably -cycloalkylene-alkylene-Rg.
As used herein, a “coupling reaction” is a reaction or reaction sequence in which the net reaction is the connection of carbon skeletons of two compounds containing a common functional group.
As used herein, “oxidation” refers to a chemical process by which an atom of an element gains bonds to more electronegative elements, most commonly oxygen. In this process, the oxidized element increases its oxidation state, which represents the charge of an atom. Oxidation reactions are commonly coupled with “reduction” reactions, wherein the oxidation state of the reduced atom decreases.
As used herein, a “redox reaction” or “reduction oxidation reaction” refers to a type of chemical reaction that involves a transfer of electrons between two species. An oxidation-reduction reaction is any chemical reaction in which the oxidation number of a molecule, atom, or ion changes by gaining or losing an electron.
As used herein, the term “in air” refers to a set of reaction conditions. Such conditions may comprise ambient atmosphere conditions not needing inert gasses to run a reaction. This is advantageous because it eliminates the need for specialty glassware or purchasing nitrogen or argon gas cylinders.
As used herein, the “visible spectrum” refers to a range of wavelengths within the electromagnetic spectrum, wherein the range spans about 380 nm to 700 nm. The visible spectrum may be broken up into different wavelength regions corresponding to colors including red, orange, yellow, green, blue, indigo, and violet. Certain ranges of wavelengths falling in the visible spectrum have been known to cause damage to human eyes.
As used herein, the “ultraviolet (UV) spectrum” refers to a range of wavelengths within the electromagnetic spectrum, wherein the range spans about 10 nm to 400 nm.
As used herein, “light absorption” is defined as the phenomenon wherein electrons absorb the energy of incoming light waves (i.e. photons) and change their energy state. In order for this to occur, the incoming light waves must be at or near the energy levels of the electrons. The resultant absorption patterns characteristic to a given material may be displayed using an “absorption spectrum”, wherein an “absorption spectrum” shows the change in absorbance of a sample as a function of the wavelength of incident light and may be measured using a spectrophotometer. Unique to an “absorption spectrum” is an “absorption peak”, wherein the frequency or wavelength of a given sample exhibits the maximum or the highest spectral value of light absorption. With regards to light absorption of wavelengths of light corresponding to the visible spectrum, a material or matter absorbing light waves of certain wavelengths of the visible spectrum may cause an observer to not see these wavelengths in the reflected light.
As used herein, “fluorescence” refers to a type of luminescence that occurs in gas, liquid or solid matter. Fluorescence occurs following the absorption of light waves (i.e. photons), which may promote an electron from the ground state promoted to an excited state. In fluorescence, the spin of the electron is still paired with the ground state electron, unlike phosphorescence. As the excited electron returns to the ground state, it emits a photon of lower energy, corresponding to a longer wavelength, than that of the absorbed photon.
As used herein, “phosphorescence” refers to a phenomenon of delayed luminescence that corresponds to the radiative decay of an excited electron from the molecular triplet state. As a general property, phosphorescence represents a challenge of chemical physics due to the spin prohibition of the underlying triplet-singlet photon emission and because its analysis embraces a deep knowledge of electronic molecular structure. Phosphorescence is the simplest physical process which provides an example of spin-forbidden transformation with a characteristic spin selectivity and magnetic field dependence, being the model also for more complicated chemical reactions and for spin catalysis applications. Phosphorescence is commonly viewed as the alternative method of photon emission with regards to fluorescence. Methods exist in the art to increase the amount of fluorescence versus phosphorescence emission, such as the use of heavy metals to increase spin coupling.
As used herein, the “quantum yield (Φ)” is a measure of the efficiency of photon emission as defined by the ratio of the number of photons emitted to the number of photons absorbed.
As used herein, “anisotropic” describes a material wherein a given property of said material depends on the direction in which it is measured. Moreover, something that is “anisotropic” changes in size or in its physical properties according to the direction in which it is measured. Examples of anisotropic materials may comprise graphite, carbon fiber, nanoparticles, etc.
As used herein, “isotropic” describes a material wherein a given property of said material does not depend on the direction in which it is measured. Moreover, something that is “isotropic” remains constant in size or in its physical properties according to the direction in which it is measured.
As used herein, “ligand” refers to an ion or neutral molecule that bonds to a central metal atom or ion. Example ligands may comprise PVP, PVA, DSDMA, and other molecules capable of bonding to a central metal atom. Metal atoms may comprise a variety of metals including, but not limited to, noble metals such as gold. Ligands have at least one donor with an electron pair used to form covalent bonds with the metal central atom.
As used herein, an “intermediate ligand” refers to a ligand temporarily conjugated to a metal atom that is further exchanged to allow the conjugation of an alternate ligand.
As used herein, the terms “physical absorption” or “chemical absorption” refer to processes in which atoms, molecules, or particles enter the bulk phase of a gas, liquid, or solid material and are taken up within the volume. Absorption in this manner may be driven by solubility, concentration gradients, temperature, pressure, and other driving forces known in the art.
As used herein, “adsorption” is defined as the deposition of a species onto a surface. The species that gets adsorbed on a surface is known as an adsorbate, and the surface on which adsorption occurs is known as an adsorbent. Examples of adsorbents may comprise clay, silica gel, colloids, metals, nanoparticles etc. Adsorption may occur via chemical or physical adsorption. Chemical adsorption may occur when an adsorbate is held to an adsorbent via chemical bonds, whereas physical adsorption may occur when an adsorbate is joined to an adsorbent via weak van der Waal's forces.
As used herein, “colloid” refers to dispersions of wherein one substance is suspended in another. Many examples of colloids in the art contain polymers. In this aspect, polymers may be adsorbed or chemically attached to the surface of particles suspended in the colloid, or the polymers may freely move in the colloidal suspension. The presence of polymers on particles in the suspension may directly relate to “colloidal stability,” wherein “colloidal stability” refers to the tendency of a colloidal suspension to undergo sedimentation. Sedementation would result in the falling of particles out of a colloid. Polymers adsorbed or chemically attached to a particle may affect its colloidal stability.
As used herein, the term “diffusion” refers to the process wherein there is a net flow of matter from one region to another. An example of such process is “surface diffusion,” wherein particles move from one area of the surface of a subject to another area of the same surface. This can be caused by thermal stress or applied pressure.
As used herein, a “surfactant” refers to a substance that, when added to a liquid, reduces its surface tension, thereby increasing its spreading and wetting properties. Typical surfactants may be partly hydrophilic and partly lipophilic.
As used herein, the term “wetting agent” refers to a specific class of surfactant, wherein a wetting agent reduces the surface tension of water and thus allows a liquid to more easy spread on or “wet” a surface. The high surface tension of water causes problems in many industrial processes where water-based solutions are used, as the solution is not able to wet the surface it is applied to. Wetting agents are commonly used to reduce the surface tension of water and thus help the water-based solutions to spread.
“Target macromolecule” means the macromolecule being synthesized from the reactive monomer mixture comprising monomers, macromers, prepolymers, cross-linkers, initiators, additives, diluents, and the like.
The term “polymerizable compound” means a compound containing one or more polymerizable groups. The term encompasses, for instance, monomers, macromers, oligomers, prepolymers, cross-linkers, and the like.
“Polymerizable groups” are groups that can undergo chain growth polymerization, such as free radical and/or cationic polymerization, for example a carbon-carbon double bond which can polymerize when subjected to radical polymerization initiation conditions. Non-limiting examples of free radical polymerizable groups include (meth)acrylates, styrenes, vinyl ethers, (meth)acrylamides, N-vinyllactams, N-vinylamides, O-vinylcarbamates, O-vinylcarbonates, and other vinyl groups. Preferably, the free radical polymerizable groups comprise (meth)acrylate, (meth)acrylamide, N-vinyl lactam, N-vinylamide, and styryl functional groups, and mixtures of any of the foregoing. More preferably, the free radical polymerizable groups comprise (meth)acrylates, (meth)acrylamides, and mixtures thereof. The polymerizable group may be unsubstituted or substituted. For instance, the nitrogen atom in (meth)acrylamide may be bonded to a hydrogen, or the hydrogen may be replaced with alkyl or cycloalkyl (which themselves may be further substituted).
Any type of free radical polymerization may be used including but not limited to bulk, solution, suspension, and emulsion as well as any of the controlled radical polymerization methods such as stable free radical polymerization, nitroxide-mediated living polymerization, atom transfer radical polymerization, reversible addition fragmentation chain transfer polymerization, organotellurium mediated living radical polymerization, and the like.
A “monomer” is a mono-functional molecule which can undergo chain growth polymerization, and in particular, free radical polymerization, thereby creating a repeating unit in the chemical structure of the target macromolecule. Some monomers have di-functional impurities that can act as cross-linking agents. A “hydrophilic monomer” is also a monomer which yields a clear single phase solution when mixed with deionized water at 25° C. at a concentration of 5 weight percent. A “hydrophilic component” is a monomer, macromer, prepolymer, initiator, cross-linker, additive, or polymer which yields a clear single phase solution when mixed with deionized water at 25° C. at a concentration of 5 weight percent. A “hydrophobic component” is a monomer, macromer, prepolymer, initiator, cross-linker, additive, or polymer which is slightly soluble or insoluble in deionized water at 25° C.
A “macromolecule” is an organic compound having a number average molecular weight of greater than 1500, and may be reactive or non-reactive.
A “macromonomer” or “macromer” is a macromolecule that has one group that can undergo chain growth polymerization, and in particular, free radical polymerization, thereby creating a repeating unit in the chemical structure of the target macromolecule. Typically, the chemical structure of the macromer is different than the chemical structure of the target macromolecule, that is, the repeating unit of the macromer's pendent group is different than the repeating unit of the target macromolecule or its mainchain. The difference between a monomer and a macromer is merely one of chemical structure, molecular weight, and molecular weight distribution of the pendent group. As a result, and as used herein, the patent literature occasionally defines monomers as polymerizable compounds having relatively low molecular weights of about 1,500 Daltons or less, which inherently includes some macromers. In particular, monomethacryloxypropyl terminated mono-n-butyl terminated polydimethylsiloxane (molecular weight=500-1500 g/mol) (mPDMS) and mono-(2-hydroxy-3-methacryloxypropyl)-propyl ether terminated mono-n-butyl terminated polydimethylsiloxane (molecular weight=500-1500 g/mol) (OH-mPDMS) may be referred to as monomers or macromers. Furthermore, the patent literature occasionally defines macromers as having one or more polymerizable groups, essentially broadening the common definition of macromer to include prepolymers. As a result, and as used herein, di-functional and multi-functional macromers, prepolymers, and crosslinkers may be used interchangeably.
A “polymer” is a target macromolecule composed of the repeating units of the monomers used during polymerization. Example polymers may comprise poly(ethylene glycol) (PEG), polycarbonate, poly(vinyl alcohol) (PVA), polyvinylpyrrolidone (PVP), polystyrene (PS), polycaprolactone (PCL), ethylene oligomers or polyethylene (PE), polypropylene (PP), poly(methyl methacrylate) (PMMA), and other polymers known in the art.
As used herein, the term “thermoplastic” refers to a property of polymers, wherein the polymer may be melted, solidified, and then successfully melted and solidified again. This process may be repeated several times for thermoplastic polymers without loss of functionality.
As used herein, the term “thermoset” refers to a property of polymers, wherein a thermoset polymer forms well-defined, irreversible, chemical networks that tend to grow in three dimensional directions through the process of curing, which can either occur due to heating or through the addition of a curing agent, therefore causing a crosslinking formation between its chemical components, and giving the thermoset a strong and rigid structure that can be added to other materials to increase strength. Once a thermoset polymer has formed networks during curing, the polymer cannot be re-cured to set in a different manner.
A “homopolymer” is a polymer made from one monomer; a “copolymer” is a polymer made from two or more monomers; a “terpolymer” is a polymer made from three monomers. A “block copolymer” is composed of compositionally different blocks or segments. Diblock copolymers have two blocks. Triblock copolymers have three blocks. “Comb or graft copolymers” are made from at least one macromer.
A “repeating unit” is the smallest group of atoms in a polymer that corresponds to the polymerization of a specific monomer or macromer.
An “initiator” is a molecule that can decompose into radicals which can subsequently react with a monomer to initiate a free radical polymerization reaction. A thermal initiator decomposes at a certain rate depending on the temperature; typical examples are azo compounds such as 1,1′-azobisisobutyronitrile and 4,4′-azobis(4-cyanovaleric acid), peroxides such as benzoyl peroxide, tert-butyl peroxide, tert-butyl hydroperoxide, tert-butyl peroxybenzoate, dicumyl peroxide, and lauroyl peroxide, peracids such as peracetic acid and potassium persulfate as well as various redox systems. A photo-initiator decomposes by a photochemical process; typical examples are derivatives of benzil, benzoin, acetophenone, benzophenone, camphorquinone, and mixtures thereof as well as various monoacyl and bisacyl phosphine oxides and combinations thereof.
A “cross-linking agent” is a di-functional or multi-functional monomer or macromer which can undergo free radical polymerization at two or more locations on the molecule, thereby creating branch points and a polymeric network. Common examples are bis(2-methacryloyl)oxyethyl disulfide (DSDMA), cetyltrimethylammonium bromide (CTAB), cetyltrimethylammonium chloride (CTAC), ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, methylene bisacrylamide, triallyl cyanurate, and the like.
A “prepolymer” is a reaction product of monomers which contains remaining polymerizable groups capable of undergoing further reaction to form a polymer.
A “polymeric network” is a cross-linked macromolecule that can swell but cannot dissolve in solvents. “Hydrogels” are polymeric networks that swell in water or aqueous solutions, typically absorbing at least 10 weight percent water. “Silicone hydrogels” are hydrogels that are made from at least one silicone-containing component with at least one hydrophilic component. Hydrophilic components may also include non-reactive polymers.
An “interpenetrating polymeric network” comprises two or more networks which are at least partially interlaced on the molecular scale but not covalently bonded to each other and which cannot be separated without braking chemical bonds. A “semi-interpenetrating polymeric network” comprises one or more networks and one or more polymers characterized by some mixing on the molecular level between at least one network and at least one polymer. A mixture of different polymers is a “polymer blend.” A semi-interpenetrating network is technically a polymer blend, but in some cases, the polymers are so entangled that they cannot be readily removed.
The terms “reactive mixture” and “reactive monomer mixture” refer to the mixture of components (both reactive and non-reactive) which are mixed together and when subjected to polymerization conditions form the conventional or silicone hydrogels of the present invention as well as contact lenses made therefrom. The reactive monomer mixture may comprise reactive components such as the monomers, macromers, prepolymers, cross-linkers, and initiators, additives such as wetting agents, release agents, polymers, dyes, light absorbing compounds such as UV absorbers, pigments, dyes and photochromic compounds, any of which may be reactive or non-reactive but are capable of being retained within the resulting biomedical device, as well as pharmaceutical and nutraceutical compounds, and any diluents. It will be appreciated that a wide range of additives may be added based upon the biomedical device which is made and its intended use. Concentrations of components of the reactive mixture are expressed as weight percentages of all components in the reactive mixture, excluding diluent. When diluents are used, their concentrations are expressed as weight percentages based upon the amount of all components in the reactive mixture and the diluent.
“Reactive components” are the components in the reactive mixture which become part of the chemical structure of the polymeric network of the resulting hydrogel by covalent bonding, hydrogen bonding, electrostatic interactions, the formation of interpenetrating polymeric networks, or any other means.
The term “multi-functional” refers to a component having two or more polymerizable groups. The term “mono-functional” refers to a component having one polymerizable group.
As used herein, “electrochromism” refers to a phenomenon exhibited by certain electroactive materials with reversible and significant visible change in absorbance spectra. Electrochromism further refers to a reversible change in optical properties of a material caused by redox reactions. Redox reactions can be initiated when a material is placed on the surface of an electrode. When an electrochromic material is capable of showing several colors, it is known as “polyelectrochromic”. Changes in color may occur when a chromophore is forced to change its absorption spectrum by the application of electric potential. As a non-limiting example, the absorption may change from the UV region into the visible region.
As used herein, “organic photovoltaics (OPV)” refers to a field focusing on creating devices that convert solar energy to electrical energy. An OPV device may include one or several photoactive materials sandwiched between electrodes.
As used herein, “organic light emitting diodes (OLEDs)” refer to solid-state light devices that use flat light emitting technology in addition to two conductors between which a series of organic thin films are kept.
As used herein, “pi electrons” or “π electrons” refer to electrons residing within certain molecular orbitals. As non-limiting examples, pi electrons may reside in the pi bonds of a double bond, a triple bond, and a conjugated p orbital. As a non-limiting example, the allyl carbanion has four pi electrons.
As used herein, “antibonding pi electrons” or “π* electrons” refer to electrons residing within certain molecular orbitals. As a non-limiting example, antibonding pi electrons reside in antibonding molecular orbitals of pi bonds where antibonding orbitals weaken chemical bonds and raise energies associated therewith. As a non-limiting example, ethylene comprises a π* molecular orbital with four orbital lobes.
As used herein, “frontier molecular orbital theory (FMOT)” refers to the idea of frontier molecular orbitals of a compound at the frontier of electron occupation. This relates to a highest-occupied molecular orbital (HOMO) and a lowest-unoccupied molecular orbital (LUMO).
As used herein, “torsional strain” refers to destabilization of a molecule caused by the eclipsing of groups present on the adjacent atoms. It is the difference in the energy between a staggered and eclipsed conformation and can be qualified using a Newman projection.
Unless otherwise indicated, ratios, percentages, parts, and the like are by weight.
Unless otherwise indicated, numeric ranges, for instance as in “from 2 to 10,” are inclusive of the numbers defining the range (e.g., 2 and 10).
The present disclosure relates to polymers. Polymers can be used in a variety of electronics. Polymers can be synthesized in a variety of structures depending on a desired application. As non-limiting examples, polymers can be structured as thin sheets, thin films, sheets, films, nanoparticles, macroparticles, coatings, and the like. Polymers include but are not limited to high-performance conjugated polymers. Polymers include copolymers between a pyrrolopyrrole-based monomer and an additional polymeric repeating unit. As a non-limiting example, a pyrrolopyrrole-based monomer may include pyrrolo[3,2-b]pyrrole (H2DPP). As a non-limiting example, an additional polymeric repeating unit may be 3,4-propylenedioxythiophene (ProDOT), though other such repeating units are possible.
The present disclosure relates to synthesis of a variety of polymers. Polymers may include many functional groups disclosed herein. As a non-limiting example, polymers incorporating pyrollo-functional groups may be of interest. H2DPP is a building block that meets criteria described above for simplifying synthesis. H2DPP additionally represents a highly-tailorable chromophore. This chromophore possesses properties amendable to technologically relevant applications (e.g. organic photovoltaics (OPVs), organic light emitting diodes (OLEDs), and other such applications). H2DPPs represent a class of electron rich, 10π-electron chromophores that are easily synthesized in a single step and highly tailorable through simple structural modification. H2DPPs are capable of being quickly formed by reactions between aldehydes, anilines, and butanedione in the presence of acetic acid (Krzeszewski, M., et al., “The Tetraarylpyrrolo[3,2-b]Pyrroles—From Serendipitous Discovery to Promising Heterocyclic Optoelectronic Materials”, Acc. Chem. Res., 50 (9): 2334-2345 (2017)). Synthesis of H2DPPs can be performed in air and does not require column chromatography for purification (Janiga, A., et al., “Synthesis and Optical Properties of Tetraaryl-1,4-Dihydropyrrolo[3,2-b]Pyrroles”, Asian J. Org. Chem, 2(5): 411-415 (2013)). Chromophores may be considered tunable where functional groups at their peripheries are easily manipulated. Manipulation may include but is not limited to replacement, removal, cross-linking, and the like. Functionalization and tunability may be related to starting groups.
As a non-limiting example, acetaminophen may be used as a starting group. Acetaminophen may be used as a starting material for introducing solubilizing handles to H2DPP monomers. Kirkus, M., et al., “Synthesis and Optical Properties of Pyrrolo[3,2-b]pyrrole-2,5(1H,4H)-dione (iDPP)-Based Molecules,” J. Phys. Chem. A, 117(13): 2782-2789 (2013); Cho, H.H., et al., “Synthesis and Side-Chain Engineering of Phenylnaphthalenediimide (PNDI)-Based n-type Polymers for Efficient All-Polymer Solar Cells,” J. Mater. Chem. A, 5(11): 5449-5459 (2017). As shown in the scheme below, acetaminophen enables a more robust synthetic pathway for side chain engineering that exploits a two-step process starting with the alkylation of acetaminophen followed by deprotection via hydrolysis of the acetyl group.
The present disclosure relates to optimized reaction conditions and expanded functional group tolerance. This allows families of chromophores with diverse functionality to be readily synthesized (Krzeszew ski, M., et al., “Tetraaryl-, Pentaaryl-, and Hexaaryl-1,4-Dihydropyrrolo[3,2-b]Pyrroles: Synthesis and Optical Properties”, J. Org. Chem., 79 (7): 3119-3128 (2014); Tasior, M., et al., “Fe(III)-Catalyzed Synthesis of Pyrrolo[3,2-b]Pyrroles: Formation of New Dyes and Photophysical Studies”, Org. Chem. Front., 6 (16): 2939-2948 (2019); Tasior, M., et al., “Method for the Large-Scale Synthesis of Multifunctional 1,4-Dihydro-Pyrrolo[3,2-b]Pyrroles”, J. Org. Chem., 85 (21): 13529-13543 (2020)). The variety of functional groups capable of being incorporated into the periphery of H2DPPs allows chromophores to exhibit tunable optical properties (Tasior, M., et al., “Synthesis of Bis(Arylethynyl)Pyrrolo[3,2-b]Pyrroles and Effect of Intramolecular Charge Transfer on Their Photophysical Behavior”, Chem. Euro. J., 25 (2): 598-608 (2019); Banasiewicz, M., et al., “Electronic Communication in Pyrrolo[3,2-b]Pyrroles Possessing Sterically Hindered Aromatic Substituents”, Eur. J. Org. Chem., 2019 (31-32): 5247-5253 (2019)), aggregation-induced emission (Sadowski, B., et al., “Tetraphenylethylenepyrrolo[3,2-b]Pyrrole Hybrids as Solid-State Emitters: The Role of Substitution Pattern”, Org. Lett., 20 (11): 3183-3186 (2018); Hatanaka, S., et al., “Tris(Pentafluorophenyl)Borane-Pyrrolo[3,2-b]Pyrrole Hybrids: Solid-State Structure and Crystallization-Induced Enhanced Emission”, ChemPhotoChem, 4 (2): 138-143 (2020)), and two-photon fluorescence (Qin, Y., et al., “Direct Observation of Different One- and Two-Photon Fluorescent States in a Pyrrolo[3,2-b]Pyrrole Fluorophore”, J. Phys. Chem. Lett., 11 (12): 4866-4872 (2020)). Such tunability can also be impacted by cross couplings that systematically alter the resulting properties of a chromophore. Ease of tunability and versatility allows the use of H2DPPs in various optoelectronic applications (e.g. OPVs, OLEDs, etc.).
As it relates to photovoltaic studies, a small-molecule acceptor-donor-acceptor system via functionalization of the 2- and 5- position aryl rings of H2DPP with dicyanovinylenes has been shown (Domínguez, R., et al., “Pyrrolo[3,2-b]Pyrrole as the Central Core of the Electron Donor for Solution-Processed Organic Solar Cells”, Chempluschem. 82 (7): 1096-1104 (2017)). This chromophore was used as the light-harvesting material in OPV devices and achieved a maximum PCE of 1.06%. Other efforts have involved extending the conjugated pathway between the H2DPP core and acceptor region through the addition of thienyl or carbazole moieties, which resulted in a PCE of up to 6.56% when using these dyes in a dye-sensitized solar cell (DSSC) (Wang, J., et al., “Organic Dyes Based on Tetraaryl-1,4-Dihydropyrrolo-[3,2-b]Pyrroles for Photovoltaic and Photocatalysis Applications with the Suppressed Electron Recombination”, Chem. Euro. J., 24 (68): 18032-18042 (2018)). Zhang et al. synthesized an acceptor-donor-acceptor H2DPP using benzothiadiazole at the 2,5-aryl position to yield a chromophore exhibiting red emission with a solution fluorescence quantum yield (Φ) of 57% and a maximum external quantum efficiency (EQE) of 3.4% in an OLED device (Zhou, Y., et al., “Efficient Solution-Processed Red Organic Light-Emitting Diode Based on an Electron-Donating Building Block of Pyrrolo[3,2-b]Pyrrole”, Org. Electron., 65: 110-115 (2019)). Finally, H2DPPs have been used in resistive memory devices and organic photodetectors (Canjeevaram, B., “Quadrupolar (A-π-D-π-A) Tetra-Aryl 1,4-Dihydropyrrolo[3,2-b]Pyrroles as Single Molecular Resistive Memory Devices: Substituent Triggered Amphoteric Redox Performance and Electrical Bistability”, J. Phys. Chem. C, 120 (21): 11313-11323 (2016). While these examples highlight the potential applicability of molecular H2DPP materials, there is not an example of H2DPPs being directly incorporated into a polymeric main chain, thus, fundamental structure-property relationships of polymer-containing H2DPPs are unknown.
The present disclosure relates to uses of H2DPP as a monomeric building block for synthesizing conjugated polymers. As previously discussed H2DPP possesses easily tailored chromophores, combined with simple synthesis and purification techniques. The synthesis includes synthesizing a di-brominated H2DPP. Di-brominating H2DPPs enables the synthetically simple H2DPP comonomer to further participate in Pd-catalyzed polymerizations. As non-limiting examples, synthetically simple monomers provide several advantages. At least, synthetically simple monomers reduce sime requirements and lower the environmental impact of synthesis. An additional, non-limiting advantage includes lowered production costs. The present disclosure relates to a novel incorporation of H2DPPs into repeating units of the main chain of a polymer. Such polymer may be a copolymer. Additionally, the present disclosure relates to the use of monomers functionalized with side chains incorporated into the main chains of polymers.
The present disclosure relates to the first use of an H2DPP-containing copolymer synthesized via direct heteroarylation polymerization (DHAP) with 3,4-propylenedioxythiophene (ProDOT) as a co-monomer. The use of DHAP presents several advantages over the art. As non-limiting examples, DHAP at least reduces monomer preparation steps. This saves time and money by reducing the potential use of extra reagents and the potential generation of extra waste that would be need to be disposed. The present disclosure further relates to studies of structure-property relationships of this novel material by understanding how monomer structures influence synthetic accessibility, optical, thermal, and electrochemical properties. Additionally, the synthetic complexity that reveals the first H2DPP copolymer to be amongst the simplest conjugated polymers to be synthesized is quantified. As shown in
The present disclosure additionally relates to uses of an H2DPP-containing copolymer synthesized via direct heteroarylation polymerization (DHAP) with other co-monomers. In such example, an H2DPP-containing copolymer can be synthesized where an electron-deficient monomer serves as a co-monomer. Examples of electron-defficient co-monomers include but are not limited to diketopyrrolopyrrole (ketoDPP) and thienylpyrrolodione (TPD), as shown in
The present disclosure additionally relates to synthesis of H2DPP copolymers via Suzuki poly-condensation reactions, as shown in
The present disclosure relates to simplified methods of polymer synthesis. Polymers include high-performance conjugated polymers. Simplified methods of polymer synthesis address solubility concerns relating to conjugated polymers. In doing so, the simplified methods synthesize H2DPP monomers that are capable of being used in soluble copolymers. Solubility concerns may arise where a conjugated polymer is not soluble. This may make synthesizing said conjugated polymer difficult where it is not amenable to high-throughput solution processing.
The present disclosure relates to approaches that eliminate or reduce process steps requiring air-free reactions, producing toxic byproducts, requiring chromatography for purification, and using high temperature/pressure or cryogenic reaction conditions. By eliminating such factors, synthesis is simplified. As a non-limiting example, reactions described herein may be conducted at temperatures ranging from about 20° C. up to about 200° C. In a particular non-limiting example, reactions described herein may be conducted at temperatures ranging from about 50° C. up to about 140° C.
The present disclosure relates to simplified monomer and polymer synthetic steps. As a non-limiting example, the present disclosure relates to synthesis of a dibrominated dihydropyrrolopyrrole in air. In such an example, a single synthetic step is used that does not require column chromatography for purification. This shows the first example of a pyrrolopyrrole monomer being polymerized. Polymerization occurs via direct arylation polymerization using a dioxythiophene comonomer to access an alternating copolymer in a total of three synthetic steps. The resulting copolymer exhibits absorbance in the high-energy portion of the visible spectrum in solution and the solid state (
Conjugated polymers have traditionally been synthesized via Pd-catalyzed cross-coupling reactions, but these synthetic strategies suffer restrictive synthetic barriers in their respective procedures, such as monomer stability and potentially costly/toxic functionalization steps (Sakamoto, J., et al., “Polycondensation: Polyarylenes à La Carte”, Macromol. Rapid Commun. 30: 653-687 (2009); Carsten, B., et al., “Stille Polycondensation for Synthesis of Functional Materials”, Chem. Rev. 111 (3): 1493-1528 (2011)). The present disclosure improves upon these syntheses by minimizing the use/generation of toxic reagents. In doing so, direct heteroarylation polymerization (DHAP) is used to access synthetically simple conjugated polymers. DHAP is a green alternative polymerization strategy because it minimizes monomer preparation steps while simultaneously minimizing/eliminating toxic reagents by forgoing the need for organometallic reagents that participate in the transmetallation process of Pd-catalyzed cross-couplings (Mainville, M., et al., “Direct (Hetero)Arylation: A Tool for Low-Cost and Eco-Friendly Organic Photovoltaics”, ACS Appl. Polym. Mater, 3 (1): 2-13 (2021); Blaskovits, J. T. et al., “C—H Activation as a Shortcut to Conjugated Polymer Synthesis”, Macromol. Rapid Commun., 40 (1): 1800512 (2019); Pouliot, J. R., et al., “Direct (Hetero)Arylation Polymerization: Simplicity for Conjugated Polymer Synthesis”, Chem. Rev., 116 (22): 14225-14274 (2016); Pankow, R. M., et al., “The Development of Conjugated Polymers as the Cornerstone of Organic Electronics”, Polymer (Guildf), 207: 122874 (2020)). Additionally, DHAP is a robust polymerization strategy that enables accessing low-defect conjugated polymers without sacrificing device performance metrics (Ponder Jr, J. F., et al., “Low-Defect, High Molecular Weight Indacenodithiophene (IDT) Polymers Via a C—H Activation: Evaluation of a Simpler and Greener Approach to Organic Electronic Materials”, ACS Mater. Lett., 3 (10): 1503-1512 (2021)).
Initial polymerization attempts relating to the present disclosure to incorporate H2DPP as a comonomer into conjugated polymers were attempted with thienopyrroledione (TPD). TPD is a previously studied comonomer and shows a propensity to participate in DHAP (Pron, A., et al., “Thieno[3,4-c]Pyrrole-4,6-Dione-Based Polymers for Optoelectronic Applications”, Macromol. Chem. Phys., 214: 7-16 (2013)). Initial attempts were unsuccessful at obtaining copolymers with suitable solubility in organic solvents, evidenced by excessive material remaining in the Soxhlet thimble following extraction protocols in addition to bimodal molecular weight distributions measured via size-exclusion chromatography (SEC) (as shown in
The present disclosure relates to the use of 3,4-propylenedioxythiophene (ProDOT) as a comonomer for direct arylation polymerizations with H2DPP. ProDOT offers facile tunability and synthetically simple monomers. This stems from its one-step synthesis and ease of functionalization for reactivity with numerous polymerization methods such as Grignard metathesis, oxidative polymerization, and Pd-catalyzed cross-couplings (Collier, G. S., et al., “Exploring the Utility of Buchwald Ligands for C—H Oxidative Direct Arylation Polymerizations”, ACS Macro Lett., 8 (8): 931-936 (2019)). Furthermore, various solubilizing motifs can be installed onto ProDOT in one or two steps via transetherification reactions that utilize commercially available starting materials, such as 2,2-di-n-octyl-1,3-propanediol (Reeves, B. D., et al., “Spray Coatable Electrochromic Dioxythiophene Polymers with High Coloration Efficiencies”, Macromolecules, 37 (20): 7559-7569 (2004)). Due to this tailoribility, ProDOT polymers have been used as electroactive material in various organic electronics such as electrochromics and OPVs (Dey, T., et al., “Poly(3,4-Propylenedioxythiophene)s as a Single Platform for Full Color Realization”, Macromolecules, 44 (8): 2415-2417 (2011); Mazaheripour, A., et al., “Nonaggregating Doped Polymers Based on Poly(3,4-Propylenedioxythiophene)”, Macromolecules, 52 (5): 2203-2213 (2019); Thompson, B. C., et al., “Soluble Narrow Band Gap and Blue Propylenedioxythiophene-Cyanovinylene Polymers as Multifunctional Materials for Photovoltaic and Electrochromic Applications”, J. Am. Chem. Soc., 128 (39): 12714-12725 (2006)). The use of ProDOT further provides the ability to understand structure-property relationships of H2DPP-based copolymers.
The present disclosure relates to new monomers that efficiently participate in polymerization protocols while simultaneously lowering synthetic complexity and reducing toxicities associated with various reagents, pathways, and the like. Methods for minimizing synthetic steps while also removing toxic and air/moisture sensitive reagents during synthetic procedures are provided herein. The present disclosure displays the first example of an H2DPP comonomer being directly incorporated into the main chain of a polymer repeat unit and providing foundational structure-property relationships of a novel class of polymeric material. As a non-limiting example, H2DPP is used to create a H2DPP-co-ProDOT copolymer.
As a non-limiting example of a synthesis, dibrominated H2DPP comonomers are synthesized in one aerobic synthesis, purified via vacuum filtration, and are amendable to scalable preparations without sacrificing the purity required for efficient polymerizations. H2DPP monomers are successfully incorporated into an electroactive conjugated polymer via direct arylation polymerization with a ProDOT comonomer, which enables studying monomer influence on properties such as degradation temperature, absorbance and fluorescence, and oxidation potential. Time-dependent density functional theory (TD-DFT) aids in explaining the wide bandgap absorbance features as well as the amorphous nature of the polymer in bulk and thin film samples by understanding the influence of dihedral angles on these properties. Electrochemical studies reveal the quasi-reversible redox nature of H2DPP-co-ProDOT as a thin film that displays yellow-to-black electrochromism with a relatively low oxidation potential (about 0.6 V vs. Ag/AgCl).
H2DPP successfully demonstrates the feasibility of generating electroactive materials while reducing the number of synthetic steps with relatively benign reagents. The present disclosure provides a new approach for simplifying the synthetic complexity commonly associated with generating conjugated polymers while also expanding the synthetic toolbox for the field of conjugated polymers.
The present disclosure is related to the following aspects.
A first aspect including a composition comprising a copolymer comprising a monomer derived from a pyrrole.
A second aspect including a composition of the first aspect, wherein the monomer is derived from a pyrrolopyrrole.
A third aspect including a composition of the second aspect, wherein the pyrrolopyrrole is pyrrolo[3,2-b]pyrrole (H2DPP).
A fourth aspect including a composition of any of the above aspects further comprising a monomer derived from a dioxythiophene.
A fifth aspect including a composition of the fourth aspect, wherein the dioxythiophene is 3,4-propylenedioxythiophene (ProDOT).
A sixth aspect including a composition of any of the above aspects further comprising a monomer of thienopyrroledione (TPD) or diketopyrrolopyrrole (ketoDPP).
A seventh aspect including a compound comprising a copolymer comprising a repeating unit, wherein the repeating unit is of the following formula
wherein R1 comprises a functional group selected from the following formulas or C10H21
wherein Ar is an aromatic compound selected from the following formulas
and wherein R2 is C8H17 and R3 is EtHx.
An eighth aspect including a method of synthesizing a copolymer repeat unit derived from a pyrrole and a monomer derived from a dioxythiophene, the method comprising:
A ninth aspect including a method of the eighth aspect, wherein the pyrrole-derived monomeric unit is dibrominated.
A tenth aspect of incorporating at least one H2DPP molecule into a repeat unit of a copolymer, the method comprising a reaction comprising:
An eleventh aspect including a method of the tenth aspect, wherein the dibrominated, pyrrole-derived monomeric unit is of the following formula
and wherein R1 comprises a functional group selected from the following formulas or C10H21
A twelfth aspect including a method of the tenth or eleventh aspect, wherein the aromatic compound is selected from the following formulas
and wherein R2 is C8H17 and R3 is EtHx.
A thirteenth aspect including a method of any of the tenth, eleventh, or twelfth aspect, wherein the solution comprises Pd(OAc)2 and PivOH.
A fourteenth aspect including a method of the thirteenth aspect, wherein the solution further comprises PCy3, HBF4, and Cs2CO3.
A fifteenth aspect including a method of the thirteenth or fourteenth aspect, wherein the solution further comprises DMAc.
A sixteenth aspect including a method of any of aspects ten through fifteen, wherein the reaction is carried out at a temperature from about 50° C. up to about 140° C.
A seventeenth aspect including a method of any of aspects ten through sixteen, wherein the reaction is carried out at a temperature of about 140° C.
Copolymers were synthesized using Suzuki reactions, as shown in
aPd(PPh3)4
aPd(PPh3)4
aPurified via vacuum filtration and washing with MeOH
Analytical results of the products obtained above are provided. 2,5-bis(phenyl)-1,4-bis(4-n-decylphenyl)-1,4-dihydropyrrolo[3,2-b]pyrrole-co-9,9-Dioctylfluorene (DHPP-co-FL): Brown Solid. Yield: 279 mg (88%) 1H NMR (400 MHz, CDCl3), δ: 0.70 (s, 3H), 0.79 (t, 9H), 0.88 (t, 9H), 1.05-1.19 (m, 28H), 1.28-1.39 (m, 41H), 1.63-1.70 (m, 6H), 2.02 (s, 3H), 2.66 (t, 5H), 6.48 (s, 2H), 6.48 (s, 2H), 7.19-7.35 (m, 18H), 7.55-7.62 (m, 8H), 7.72-7.77 (m, 2H). Anal. calc'd for C81H106N2: C 87.83; H 9.65; N 2.53 Found: C 87.59; H 9.38; N 2.62. Mn=10.6 kg/mol Mw=51.1 kg/mol Mw/Mn=4.8.
2,5-bis(phenyl)-1,4-bis(4-n-decylphenyl)-1,4-dihydropyrrolo[3,2-b]pyrrole-co-9-Heptadecan-9-ylcarbazole (DHPP-co-Car): Dark-Brown Solid. Yield: 213.5 mg (63%) 1H NMR (400 MHz, CDCl3), δ: 0.77-0.83 (m, 9H), 0.87 (t, 9H), 1.13-1.40 (m, 90H), 1.63-1.70 (m, 7H), 1.96 (s, 2H), 1.96 (s, 2H), 2.35 (2H), 2.65 (t, 5H), 4.64 (s, 2H), 6.50 (s, 2H), 7.19-7.25 (m, 8H), 7.33 (dd, J=23.4, 8.1 Hz, 11H), 7.46 (d, 4H), 7.58-7.61 (m, 6H), 7.70-7.75 (m, 2H). Anal. calc'd for C81H107N3: C 86.65; H 9.61; N 3.74 Found: C 85.17; H 9.12; N 3.79. Mn=7.9 kg/mol Mw=14.4 kg/mol Mw/Mn=1.8.
Additional copolymers were synthesized using Suzuki reactions, as shown in
Analytical results of the products obtained above are provided. 2,5-bis(4-fluoro-3-hexyldecyletherphenyl)-1,4-bis(phenyl)-1,4-dihydropyrrolo[3,2-b]pyrrole-co-thiophene (F,ORDPP-co-Th): Pale-yellow solid. Yield: 133 mg (70%). 1H NMR: (400 MHz, CDCl3), δ: 0.87-0.92 (m, 15H), 1.26-1.40 (m, 62H), 1.68-1.71 (m, 3H), 3.62-3.70 (m, 4H), 6.45-6.46 (m, 2H), 6.76-6.86 (m, 4H), 6.95-7.02 (m, 3H), 7.32-7.35 (m, 5H), 7.68 (d, J=8.3 Hz, 4H). Anal. calc'd for C66H84F2N2O2S Theory: C, 78.53; H, 8.59; N, 2.78; S, 3.18 Actual: C, 77.57; H, 8.36; N, 2.86; S, 2.87. Mn=16 kg/mol Mw=67 kg/mol Mw/Mn=4.2.
2,5-bis(4-hexyldecyletherphenyl)-1,4-bis(phenyl)-1,4-dihydropyrrolo[3,2-b]pyrrole-co-thiophene (4-ORDPP-co-Th): Dark-brown solid. Yield: 146 mg (79%). 1H NMR: (400 MHz, CDCl3), δ: 0.88-0.92 (m, 15H), 1.29-1.49 (m, 62H), 1.76-1.81 (m, 3H), 3.84 (d, 4H), 6.34-6.41 (m, 2H), 6.79-6.85 (m, 4H), 7.07-7.23 (m, 6H), 7.30-7.35 (m, 5H), 7.49 (d, J=8.5 Hz, 1H), 7.61-7.66 (m, 4H). Anal. calc'd for C66H84N202S Theory: C, 81.43; H, 9.11; N, 2.88; S, 3.29 Actual: C, 79.51; H, 8.67; N, 2.89; S, 2.83. Mn=7.1 kg/mol Mw=9.7 kg/mol Mw/Mn=1.4.
Efforts to address solubility concerns relating to simplified synthesis of high-performance conjugated polymers began with attempting to synthesize H2DPP using 4-aminophenol and 4-bromobenzaldehyde followed by alkylation protocol (Wang, J., et al., “Organic Dyes Based on Tetraaryl-1,4-Dihydropyrrolo[3,2-b]Pyrroles for Photovoltaic and Photocatalysis Applications with the Suppressed Electron Recombination”, Chem. Euro. J., 24 (68): 18032-18042 (2018)), as shown in
(OH)2DPP was obtained with a favorable yield of 55%. Subsequent alkylation attempts via Williamson etherification resulted in yields between 5-8%.
In an effort to improve yields of alkylation via Williamson etherification, and overall atom economy, 4-aminophenol was replaced with 4-n-decylaniline to access a monomer amendable to Pd-catalyzed polymerizations in one-step, in air, and requiring simple purification(s) (e.g. vaccum filtration). 4-Decylaniline was chosen as it was hypothesized to be a suitable solubilizing handle for the resulting polymers, thus enabling thorough characterization and eventually solution proces sibility.
As shown in
In order to polymerize H2DPP with ProDOT, an established DHAP procedure for producing poly(ProDOT)s that uses the high dielectric solvent N,N-dimethylacetamide (DMAc), palladium(II) acetate (Pd(OAc)2) as the catalyst, potassium carbonate (K2CO3) as the base, and pivalic acid (PivOH) as the proton shuttle while heating the reaction mixture at 140° C. was used (Estrada, L. A., et al., “Direct (Hetero)Arylation Polymerization: An Effective Route to 3,4-Propylenedioxythiophene-Based Polymers with Low Residual Metal Content”, ACS Macro Lett., 2 (10): 869-873 (2013)). The 3,6-position hydrogens of H2DPP, illustrated as the red protons in
Optical properties of H2DPP-co-ProDOT described herein were quantified using UV-vis and fluorescence spectroscopies. After successful synthesis, calculations to probe fundamental structural and optical properties were made. Excited state transitions of a (ProDOT)2DPP oligomer were calculated via time-dependent density functional theory (TD-DFT) using the mPW1PBE functional paired with the cc-PVDZ basis set. These parameters were chosen because they have been shown to accurately correlate calculated and experimental absorbance spectra of ProDOT-containing oligomers (Wheeler, D. L., et al., “Modeling Electrochromic Poly-Dioxythiophene-Containing Materials Through TDDFT”, Phys. Chem. Chem. Phys., 19 (30): 20251-20258 (2017); Collier, G. S., et al., “Exploring Isomeric Effects on Optical and Electrochemical Properties of Red/Orange Electrochromic Polymers”, Macromolecules, 54 (4): 1677-1692 (2021)).
Calculated dihedral angles were consistent with previous electronic structure calculations as well as dihedral angles found for published H2DPP crystal structures, thus supporting the level of theory (Banasiewicz, M., et al., “Electronic Communication in Pyrrolo[3,2-b]Pyrroles Possessing Sterically Hindered Aromatic Substituents”, Eur. J. Org. Chem., 2019 (31-32): 5247-5253 (2019); Sadowski, B., et al., “Tetraphenylethylenepyrrolo[3,2-b]Pyrrole Hybrids as Solid-State Emitters: The Role of Substitution Pattern”, Org. Lett., 20 (11): 3183-3186 (2018)). The frontier molecular orbital maps (
As shown in
Initial understanding of H2DPP-co-ProDOT thermal properties, such as degradation temperature (Td), glass transition (Tg), and crystallization temperature (Ta), were studied using thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), respectively. TGA was used to determine the degradation temperature of H2DPP-co-ProDOT by measuring the mass loss as a function of temperature.
Due to the electron-rich nature of H2DPP and ProDOT, redox behavior of H2DPP-co-ProDOT as thin films was studied. First, films were spray-cast from 2 mg/mL toluene on to ITO electrodes.
When the UV-vis absorbance spectrum of the resulting film was measured, there was minimal change in the absorbance profile from solution to a pristine film. Typically, conjugated polymers exhibit a distinct red-shift in the absorbance spectrum in the solid state when compared to solution due to an increase in π-πinteractions that facilitate ordering. The lack of change in the absorbance spectrum indicated minimal interchain π-πorbital overlap in the solid state. This was attributed to the large dihedral angles through the polymer backbone that prevented efficient interchain polymer interactions.
After comparing the optical properties of the H2DPP-co-ProDOT copolymer in solution and as a pristine film, films were electrochemically conditioned to study the optical properties after subjecting the films to repeated redox reactions. Electrochemical conditioning was necessary because redox-active polymers often display distinct changes in their redox response and optical properties with repeated exposure to redox reactions (Heinze, J., et al., “Electrochemistry of Conducting Polymers—Persistent Models and New Concepts”, Chem. Rev., 110 (8): 4724-4771 (2010)). Electrochemical conditioning protocols consisted of performing 10 cyclic voltammetry (CV) cycles across a voltage window of −0.5 V to 1.0 V (vs. Ag/AgCl reference electrode) in a 0.5 M TBAPF6/PC electrolyte solution using a scan rate of 100 mV/s.
Upon electrochemical conditioning, there was only a slight broadening of the absorbance profile and the λmax was unchanged, as shown in
Next, the electrochemical properties were studied using cyclic voltammetry (CV).
As shown in
Absorbance as a function of electrochemical potential was studied, and the results are plotted in
Colorimetric analysis of polymer films was subsequently performed based on the “Commision Internationale de l'Eclairage” 1976 L*a*b* color standards.
Colorimetry data shown in
The long-term electrochemical stability was measured by applying square-wave potential steps from −0.5 V to 1.0 V vs Ag/AgCl to switch films under an argon atmosphere.
As shown in
A goal of this project was to demonstrate the utility of H2DPP as a useful building block for simplifying the synthesis of conjugated polymers. The synthetic complexity (SC) was quantified using the equation developed by Po et al. as follows:
SC provided a reasonable starting point for comparing the synthetic complexity of H2DPP-co-ProDOT to the field. In the above equation, the 5 variables were defined as the number of synthetic steps (NSS), the reciprocal yield of monomers (RY), the number of operations required for purification of monomers (NUO), the number of column chromatography purifications (NCC), and the number of hazardous materials used (NHC), all of which were assigned a weighted value based on the influence each step has on potential cost implications, such as personnel or waste disposal.
As shown in entry 5 of Table 2 below, the SC of H2DPP-co-ProDOT was calculated to be 13.8 and this represented a synthetically simple conjugated polymer.
aFor a comprehensive tabulation of synthetic complexity for conjugated polymers, readers are directed to the work described in Ref. 5.
Poly(3-hexylthiophene) (P3HT) (entry 1, Table 2) had a synthetic complexity value of 7.8 but was hampered by using Grignard reagents and, ultimately, possessed modest device performance metrics (Baran, D., et al., “Reducing the Efficiency-Stability-Cost Gap of Organic Photovoltaics with Highly Efficient and Stable Small Molecule Acceptor Ternary Solar Cells”, Nat. Mater., 16 (3): 363-369 (2017); Guo, X. et al., “High Efficiency Polymer Solar Cells Based on Poly(3-Hexylthiophene)/Indene-C70 Bisadduct with Solvent Additive”, Energy Environ. Sci., 5 (7): 7943-7949 (2012)). The synthetic complexity of PTQ10 (entry 2, Table 2) also was calculated to be synthetically simple, as expected, due to the minimization of preparatory steps. However, the synthesis of PTQ10 monomers involves the use of potassium tert-butoxide, which is a flammable solid that is classified as self-heating in large quantities. Additionally, starting material and precursors are expensive, and polymers are synthesized via Stille cross-coupling polymerizations, which generate stoichiometric amounts of trialkyltin waste. Rech et al. performed a cost analysis of PTQ10 and suggest current synthetic approaches are cost prohibitive. These drawbacks limit the scalability and commercial manufacturing of this polymer and motivated the pursuit of alternative synthetic approaches that ultimately reduced the price per gram to about 1/7th the original cost (Rech, J. J., et al., “Designing Simple Conjugated Polymers for Scalable and Efficient Organic Solar Cells”, ChemSusChem, 14 (17): 3561-3568 (2021)). Notably, when calculating the synthetic complexity of the proposed cost-effective route for PTQ10 reported by Rech et al. (entry 3, Table 2), the addition of synthetic steps led to nearly doubling the synthetic complexity compared to the original synthetic strategy and resulted in a copolymer more synthetically complex than H2DPP-co-ProDOT. While both PTQ10 approaches represented simple synthetic strategies for conjugated polymers, Stille cross-coupling polymerizations were used in both syntheses, which is detrimental to scalability efforts due to the generation of stoichiometric amounts of toxic waste.
Finally, given the potential applicability in redox applications, the SC of H2DPP-co-ProDOT was compared to poly(ProDOT) (SC=21.3, entry 4, Table 2) and H2DPP-co-ProDOT was calculated to be less synthetically complex than poly(ProDOT)). H2DPP has been shown to be a viable monomer to simplify the synthesis of conjugated polymers for, potentially, both solid-state and redox applications. H2DPP-co-ProDOT was synthetically simple and was able to remove toxic reagents (tin) and air/moisture sensitive reagents (Grignards), showing H2DPP-containing copolymers offer significant advantages compared to other conjugated systems.
All chemicals were purchased from commercial sources and used as received unless otherwise noted. Anhydrous N,N-dimethylacetamide (DMAc) was degassed with argon (Ar) for 15 minutes before use. 60 Å silica gel (200-400 mesh) was used for column chromatography.
1H and 13C NMR spectra were collected on a Bruker Ascend 400 MHz NMR spectrometer with a 10-15 mg/mL nominal sample concentration in CDCl3. Peaks were referenced to the residual CDCl3 peak (1H: δ=7.26 ppm; 13C: δ=77.23 ppm).
Solution absorbance spectra were acquired using a Varian Cary 4000 dual beam UV-vis-near-IR spectrophotometer scanning from 300 to 800 nm using a 20-40 μg/mL concentration in toluene.
Solution emission spectra were acquired using an Ollis is DM45 spectrofluorimeter scanning from 10 nm above λmaxabs to 800 nm using a toluene solution with nominal concentration of 20-40 μg/mL.
Solution quantum yield was acquired using a Horiba Scientific Fluorolog-QM 75-11 equipped with an integrating K-sphere.
Thermogravimetric analysis (TGA) measurements were made using a PerkinElmer TGA 8000 using a temperature range of 30° C. to 900° C. with a heating rate of 5° C./min. The thermal degradation temperature (Td) was obtained at 5% mass loss of a 5-10 mg polymer sample in a ceramic pan.
Differential scanning calorimetry (DSC) measurements were obtained using a Shimadzu DSC-60 with a heat-cool-heat cycle from 30° C. to 310° C. using a heating rate of 10° C./min.
Spectroelectrochemistry measurements were performed using a Varian Cary 5000 Scan dual-beam UV-vis-near-IR spectrophotometer.
The absorbances collected with this same spectrophotometer were converted to colorimetric coordinates using Star-Tek colorimetry software using a D50 illuminant, 2 deg observer, and the CIELAB L*a*b* color space.
Electrochemical measurements were performed using an EG&G Princeton Applied Research model 273A potentiostat/galvanostat under CorrWare control in a three-electrode cell configuration, using ITO/glass (Delta Technologies Inc., 7×50×0.7 mm, sheet resistance, Rs 8-12 Ω/sq) as the working electrode, an Ag/AgCl reference electrode (calibrated versus the Fe/Fe+ redox couple, E1/2=40 mV), and a Pt flag as the counter electrode, with a 50 mV/s scan rate. The ITO slides were cleaned by sequential sonication in acetone, acetonitrile, and isopropanol, followed by a 5 min phosphonic acid treatment (10.0 mM hexadecylphosphonic acid in ethanol). An electrolyte solution of 0.5 M tetrabutylammonium hexafluorophosphate (TBAPF6, 98%, purified via recrystallization from hot ethanol) in propylene carbonate (PC) was used in all electrochemical and spectroelectrochemical measurements. PC was purified using a Vacuum Atmospheres solvent purifier.
Polymer films were spray-cast onto the ITO-coated glass slides using an Iwata airbrush at 20 psi from 2 mg/mL toluene solutions. Photography was performed in a light booth designed to exclude outside light with a D50 (5000K) lamp located at the back of the booth providing illumination, while using a Nikon D90 SLR camera with a Nikon 18-105 mm VR lens. Pictures are presented without manipulation except for cropping.
Br2DPP was synthesized following a literature procedure report by Tasior et al. (Tasior, M., et al., “Method for the Large-Scale Synthesis of Multifunctional 1,4-Dihydro-Pyrrolo[3,2-b]Pyrroles”, J. Org. Chem., 85(21): 13529-13543 (2020)) with slight modifications, as shown in
NMR data is displayed in
The scalable preparation of Br2DPP was achieved using the procedure described above but implementing a 10x increase in molar equivalents. For the initial mixture, 80.0 mmol of 4-n-decylaniline and 4-bromobenzaldehyde, 60 mL of toluene, and 60 mL of glacial acetic acid were combined into a 250 mL round-bottom flask. The final mixture included the addition of Fe(ClO4)3·xH2O (0.850 g) and 2,3-butanedione (3.5 mL, 40.0 mmol). Purification was performed using the same protocol as described in Example 12.
The yield was 14.5 g (19.6 mmol, 49%). Analytical characterization and purity matched data from Example 12.
A representative reaction scheme is shown in
Analytical characterization was consistent with previously published reports. NMR data is displayed in
A representative reaction scheme is shown in
Yields and NMR data are as follow. Yield: 13.7 mg (0.012 mmol, 10%). 1H NMR (400 MHz, CDCl3), δ=7.56 (d, 4H), 7.18-7.27 (m, 12H), 6.43 (s, 2H), 6.37 (s, 2H), 3.89-4.07 (m, 8H), 2.65 (t, 4H), 1.81 (m, 8H), 1.28 (br, m), 1.00 (br, d).
A representative reaction scheme is shown in
NMR data is displayed in
This application is a U.S. non-provisional of and claims the benefit of U.S. Provisional Application No. 63/396,834, filed Aug. 10, 2022, which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63396834 | Aug 2022 | US |
