The present invention relates to a process for preparing substituted polysiloxane compounds. In one embodiment, the present invention relates to processes for preparing methyl-, cyclopentyl-, and/or cyclohexyl-substituted polysiloxanes, and to the compounds prepared by such processes. In another embodiment, the present invention relates to coatings and/or films formed from the substituted polysiloxane compositions of the present invention, and to processes for preparing such coatings and/or films.
Polysiloxanes can be used in a variety of applications, including medical devices, space vehicles, and paints and coatings. Other applications of polysiloxanes include high-performance elastomers, membranes, electrical insulators, water repellants, anti-foaming agents, mold release agents, adhesives, and protective films.
Polysiloxanes and silsesquioxanes have been functionalized with various reactive groups (e.g., vinyl ethers, epoxy groups) and non-reactive groups (1-octene, substituted phenyls). The principle silane monomers have been methyl and phenyl. Prior to the present invention, cycloaliphatic silane monomers have not been reported due to difficulties in their preparation. Particularly, steric hindrances of cyclic alkenes have prevented others from successfully preparing these compounds.
In one embodiment, the present invention provides processes for preparing cycloaliphatic-substituted polysiloxanes, and as such fulfills a need within the art.
The present invention relates to a process for preparing substituted polysiloxane compounds. In one embodiment, the present invention relates to processes for preparing methyl-, cyclopentyl-, and/or cyclohexyl-substituted polysiloxanes, and to the compounds prepared by such processes. In another embodiment, the present invention relates to coatings and/or films formed from the substituted polysiloxane compositions of the present invention, and to processes for preparing such coatings and/or films.
In one embodiment, the present invention relates to a process for preparing substituted siloxane polymers comprising the steps of: (A) providing at least one first cyclic siloxane according to the general structure shown below:
wherein R1 and R2 are selected independently from methyl, ethyl, propyl, butyl, cyclopentyl, and cyclohexyl and wherein n is an integer from 3 to 50; (B) providing at least one second cyclic siloxane according to the general structure shown below:
wherein R3 and R4 are selected independently from hydride, methyl, ethyl, propyl, butyl, cyclopentyl, and cyclohexyl, wherein at least a portion of R3 comprises hydride, and wherein m is an integer from 3 to 50; (C) providing at least one disiloxane according to the general structure shown below:
wherein R5, R6, R7, and R8 are independently selected from hydride, methyl, ethyl, propyl, butyl, cyclopentyl, and cyclohexyl; (D) combining the at least one first cyclic siloxane, the at least one second cyclic siloxane, and the at least one disiloxane with an effective amount of ion exchange resin at a temperature from about −20° C. to about 80° C., for a time sufficient to result in condensation of at least a portion of the first and second cyclic siloxane and disiloxane; and (E) recovering at least one siloxane product.
In another embodiment, the present invention relates to a process for preparing substituted siloxane polymers comprising the steps of: (a) providing at least one first cycloalkene and at least one dichlorosilane; (b) reacting the at least one first cycloalkene with the at least one dichlorosilane thereby forming at least one cycloaliphatic dichlorosilane having a general formula according to the structure below:
wherein R is selected from cyclopentyl and cyclohexyl; (c) polymerizing the at least one cycloaliphatic dichlorosilane thereby forming at least one cyclic oligomer of polycylcoaliphatichydrosiloxane having a general formula according to the structure below:
wherein p is an integer from 3 to 50; (d) reacting a first portion of the at least one cyclic oligomer of polycylcoaliphatichydrosiloxane from Step (c) with at least one second cycloalkene thereby forming at least one cyclic oligomer of polydicycloaliphaticsiloxane having a general formula according to the structure below:
wherein the reaction is carried out in the presence of an effective amount of at least one catalyst, and wherein R1 and R2 are independently selected from cyclopentyl and cyclohexyl; (e) reacting a second portion of the at least one cyclic oligomer of polycylcoaliphatichydrosiloxane from Step (c) with the at least one cyclic oligomer of polydicycloaliphaticsiloxane from Step (d) thereby forming at least one copolymer thereof; and (f) recovering the at least one copolymer of Step (e).
In still another embodiment, the present invention relates to a process for preparing substituted siloxane polymers comprising the steps of: (i) providing at least one first cyclic siloxane according to the general structure shown below:
wherein R1 and R2 are methyl and wherein n is an integer from 3 to 50; (ii) providing at least one second cyclic siloxane according to the general structure shown below:
wherein R3 and R4 are selected independently from hydride and methyl, wherein at least a portion of R3 and R4 comprise hydride, and wherein m is an integer from 3 to 50; (iii) providing at least one disiloxane according to the general structure shown below:
wherein R5, R6, R7, and R8 are independently selected from hydride, methyl, ethyl, propyl, butyl, cyclopentyl, and cyclohexyl; (iv) combining the at least one first cyclic siloxane, the at least one second cyclic siloxane, and the at least one disiloxane with an effective amount of ion exchange resin at a temperature from about −20° C. to about 80° C., for a time sufficient to result in condensation of at least a portion of the first and second cyclic siloxane and disiloxane; and (v) recovering at least one siloxane product.
The present invention relates to a process for preparing substituted polysiloxane compounds. In one embodiment, the present invention relates to processes for preparing methyl-, cyclopentyl-, and/or cyclohexyl-substituted polysiloxanes, and to the compounds prepared by such processes. In another embodiment, the present invention relates to coatings and/or films formed from the substituted polysiloxane compositions of the present invention, and to processes for preparing such coatings and/or films.
As used herein, the term “M”, when used as a descriptor for silicone subunits, includes monoxides of silicon having the general formula R3SiO. The R-groups can vary independently among all organic and inorganic moieties including, without limitation, hydride, methyl, ethyl, propyl, butyl, pentyl, hexyl, and any regioisomers thereof including cyclic isomers such as cyclopentyl and/or cyclohexyl. Similarly, the terms “D”, “T” and “Q”, when used as descriptors of silicone subunits, includes dioxides, trioxides, and tetra-oxides of silicon respectively. Furthermore, D has the general formula R2SiO2, T has the general formula RSiO3, and Q has the general formula SiO4. The R groups of silicone units D, T, and Q are defined the same as that of unit M. Furthermore, D, T, and Q units can comprise cyclic siloxane species, wherein the cyclic backbone comprises Si—O bonds.
In one embodiment, the present invention relates to the formation of siloxanes from a combination of at least one first cyclic siloxane according to the general structure shown below:
wherein R1 and R2 are selected independently from methyl, ethyl, propyl, butyl, cyclopentyl, and cyclohexyl and wherein n is an integer from 3 to 50; at least one second cyclic siloxane according to the general structure shown below:
wherein R3 and R4 are selected independently from hydride, methyl, ethyl, propyl, butyl, cyclopentyl, and cyclohexyl, wherein at least a portion of R3 comprises hydride and wherein m is an integer from 3 to 50, and at least one disiloxane according to the general structure shown below:
wherein R5, R6, R7, and R8 are independently selected from hydride, methyl, ethyl, propyl, butyl, cyclopentyl, and cyclohexyl.
In another embodiment, the present invention relates to a process for preparing substituted siloxane polymers from a combination of at least one first cycloalkene and at least one dichlorosilane where such a combination yields, under a proper set of reaction conditions, at least one cycloaliphatic dichlorosilane having a general formula according to the structure below:
wherein R is selected from cyclopentyl and cyclohexyl. In this embodiment, the at least one cycloaliphatic dichlorosilane is subjected to polymerization to yield at least one cyclic oligomer of polycylcoaliphatichydrosiloxane having a general formula according to the structure below:
wherein p is an integer from 3 to 50. This product is then split into two portions (e.g., in halves) with the first portion being reacted with at least one second cycloalkene according to the formula above to yield at least one cyclic oligomer of polydicycloaliphaticsiloxane having a general formula according to the structure below:
wherein R1 and R2 are independently selected from cyclopentyl and cyclohexyl. This reaction is, in one embodiment, carried out in the presence of an effective amount of at least one catalyst. The second portion of the at least one cyclic oligomer of polycylcoaliphatichydrosiloxane from above is then reacted with the at least one cyclic oligomer of polydicycloaliphaticsiloxane to yield at least one copolymer product.
In another embodiment, the present invention relates to a synthetic scheme for preparing cationically polymerizable methyl, cyclopentyl, and cyclohexyl substituted polysiloxanes. In some embodiments, the desired cycloalkene and dichlorosilane are reacted at pressures of about 250 psi, and temperatures of about 120° C., thereby yielding a desired cycloaliphatic dichlorosilane. In still other embodiments the cycloalkene and dichlorosilane can be reacted at gauge pressures from about zero to about 1000 psi, or from about 100 to about 500 psi, or even from about 200 to 300 psi. Furthermore, in some embodiments the cycloalkene and dichlorosilane can be reacted at temperatures from about −20° C. to about 150° C., or from about 0° C to about 140° C., or from about 50° C. to about 130° C., or even from about 100° C. to about 125° C. Here, as elsewhere in the specification and claims, individual range limits may be combined.
Furthermore, in these and other embodiments the chlorosilane monomers oligomerize thereby producing cyclic oligomers having low molecular weights that are, on average, around 2,000 grams/mole. Polysiloxanes can then be produced through acid catalyzed ring opening polymerization of such cyclic oligomers. This process can yield high molecular weight polysiloxanes. For example, polysiloxanes having molecular weights of about 42,000 grams/mole can be produced according to this and other embodiments of the present invention. In some embodiments the polysiloxanes can be further functionalized with cycloaliphatic epoxy and alkoxy silane groups through hydrosilation.
Monomers, oligomers, and polymers can be characterized by 1H and 29Si NMR, FT-IR, and electrospray ionization mass spectroscopy (ESI-MS). Photo-induced curing kinetics and activation energies can be evaluated using photo-differential scanning calorimetry (PDSC). Differential scanning calorimetry can be used to observe physical changes in the films of the present invention that are brought about by varying the pendant groups. In general, cycloaliphatic substituents raise the glass transition temperature (Tg) and affect the curing kinetics relative to the methyl substituted polysiloxane. In some methyl-substituted embodiments the activation energies are about 144.8±8.1 kJ/mol. In some cyclopentyl- and cyclohexyl-substituted embodiments the activation energies are about 111.0±9.2, and 125.7±8.5 kJ/mol respectively.
In some embodiments chlorosilanes can be used as building blocks for making silicones and polysiloxanes of the present invention. Chlorosilanes can be used in a variety of embodiments, in part, because they are amenable to hydrosilation reactions where a Si—H compound is added to a multiple bond, such as an alkene or alkyne. In many embodiments, platinum complexes can be used as hydrosilation catalysts due to their activity at relatively low concentrations. An example of such a platinum catalyst is chloroplatinic acid (Speier's catalyst), which is reduced to a platinum (0) species in the presence of silanes and/or siloxanes. During such reactions an induction period is sometimes observed. The induction period can be reduced or eliminated by using a platinum complex such as Karstedt's catalyst. Examples of other metal-based catalysts that can be used include the rhodium-based Wilkinson's catalyst. As will be appreciated by one of ordinary skill in the art, a wide variety of catalysts are expected to perform adequately, and thus are within the scope of the present invention.
Embodiments that involve synthesis of linear siloxane polymers can be divided into two general classifications according to the pathway in which the polymer chain is formed: (1) polymerization of difunctional silanes; and (2) ring-opening polymerization of cyclic oligosiloxanes. Hydrolytic polymerization involves the polymerization of halosilanes (e.g., chlorosilanes) through the incorporation of water. Furthermore, this type of polymerization can be used in embodiments directed to synthesizing both linear siloxane polymers and/or cyclic siloxane oligomers. Embodiments for synthesizing cyclic siloxane oligomers can also be used for making substrates used in ring-opening polymerization embodiments.
Polysiloxane chains can be formed by either, or both, of the following two polymerization embodiments: homofunctional polymerization and/or heterofunctional polymerization. Homofunctional polymerization includes reacting one or more difunctional silanes such as silanediols or dichlorosilanes. Heterofunctional polymerization includes reacting one or more silanols with another functional group. In some embodiments a heterofunctional process can be used for a hydrolytic polymerization step. In such embodiments hydrolysis and polymerization generally occur more or less simultaneously.
Embodiments involving ring-opening polymerization generally enable greater control over molecular weight, thus it is often advantageous for preparing high polymers. Such embodiments can include either anionic or cationic routes, and can be either thermodynamically or kinetically controlled. In thermodynamically driven embodiments the siloxane bonds are substantially equivalent in number and in kind both in a chain and in a ring. Thus, the net energy change is very small. Accordingly, such reactions are driven by an increase in entropy arising from the siloxane segments' increased degrees of freedom. The increase in degrees of freedom stems from conversion from cyclic to linear structures. In some embodiments, the molecular weight of cyclosiloxane polymerization equilibrium products is controlled by incorporating an end-group that ensures the closure of the chain with a neutral and/or non-reactive group.
Some embodiments include preparing poly(dimethylsiloxane-co-methylhydrosiloxane) (1) functionalized with cycloaliphatic epoxides and/or alkoxy silanes. Other embodiments include synthesizing and/or functionalizing poly(dicyclopentylsiloxane-co-cyclopentylhydrosiloxane), hydride terminated (2) and poly(dicyclohexylsiloxane-co-cyclohexylhydrosiloxane), hydride terminated (3). Embodiments for preparing cycloaliphatic substituted compounds differ from that of methyl substituted in that the cyclic species needs to be synthesized by hydrolytic polymerization of cycloaliphatic substituted silanes.
Monomers for use in connection with the present invention can be characterized using 1H NMR, 29Si NMR, FT-IR, and mass spectroscopy. According to some embodiments, homopolymers can be prepared from the monomers, oligomers, and polysiloxanes.
The following materials are used in some of the examples and embodiments set forth herein. Octamethylcyclotetrasiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, 1,1,3,3-tetramethyldisiloxane, dichlorosilane, and vinyl triethoxysilane can be purchased from Gelest, Inc. and used as supplied. Wilkinson's catalyst (chlorotris(triphenylphosphine)rhodium(l), 99.99%), Karstedt's catalyst (platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, 3% w/w solution in xylenes), cyclopentene, cyclohexene, Amberlyst 15 ion-exchange resin, and 4-vinyl-1-cyclohexene 1,2-epoxide can be purchased from Aldrich and used as supplied. Toluene, supplied by Aldrich Chemical Co., can be distilled in order to eliminate any impurities. Irgacure 250 is supplied by Ciba Specialty Chemicals and can be used as received. Air sensitive materials are transferred and weighed in a dry box under argon.
The following instruments are used in some of the examples and embodiments set forth herein. Proton NMR spectra can be obtained from a Gemini-300 spectrometer (Varian), and silicon NMR spectra can be obtained on a Gemini-400 spectrometer (Varian). All NMR samples are prepared in CDCl3 and recorded at 20° C. Chemical shifts are shown relative to a TMS internal standard. FT-IR spectra are obtained on a Mattson Genesis Series FT-IR and a Waters system is used for GPC analysis. Mass spectroscopy is performed on a Saturn 2200 (Varian) in EI mode with an ion trap read out.
The Si—H bond is polarized depending to some degree on the substituents of the silicon. The reactivity of the Si—H bond makes it possible to analyze this group with qualitative or quantitative chemical tests. The Si—H is titrated via reduction of a mercury(II) salt according to the reaction set forth in Equation 1.
—Si—H+2HgCl2—Si—Cl+Hg2Cl2+HCl (1)
The HCl byproduct is then titrated against a base to determine the % Si—H in the sample.
More specifically, the Si—H determination can be carried out as follows. A mercuric chloride solution (about 4% w/v in 1:1 chloroform-methanol) is pipetted (about 20 mL) into an Erlenmeyer flask. The sample to be titrated is added and agitated before adding a calcium chloride solution (about 15 mL, saturated solution in methanol). Phenolphthalein indicator is added (about 15 drops) after about 5 to 6 minutes, and the solution is titrated with 0.1 N alcoholic potassium hydroxide. Controls are titrated in the same manner before and after the analysis. The calculation for % Si—H is shown in equation 2.
% H═[(V1−V2)](NKOH)(1.008/2000)(100)/sample wt (g) (2)
In reference to Equation 2, V, is the endpoint, V2 is the averaged blanks, and N is the normality of the basic titrant.
Some embodiments include a photoinitiation step. This step can be performed in a variety of acceptable ways. In one example, a 2 to 3 mg sample (polymer and 3% photoinitiator w/w) is placed in an uncovered, hermetic, aluminum DSC pan. An empty pan is used as a reference. The chamber of the DSC is purged with nitrogen before the polymerization and purging continues throughout the reaction. The samples are photo-cured with UV light (150 mW/cm2) for any of a variety of exposure times (1, 5, and 15 seconds) and temperatures (−10° C., 25° C., and 60° C.). The heat flux as a function of reaction time can be monitored under isothermal conditions, and the rate of polymerization can be calculated. The heat of reaction (ΔHR) for the epoxy group is 23.13 Kcal/mol.
The rate of propagation (Rp) is directly proportional to the rate at which heat is released from the reaction. As a result, the height of the DSC exotherm can be used to quantify the rate of polymerization. An applicable rate formula for the photo-polymerization is set forth in equation 3.
Rp=((Q/s).M)/(n.ΔHR.m) (3)
With reference to Equation 3, Q/s is the heat flow per second released during the reaction, and is in units of Joules per second. The variable M is the molar mass of the reacting species, n is the average number of epoxy groups per polymer chain, and m is the mass of the sample.
A synthesis diagram showing the functionalization of poly(dimethylsiloxane-co-methylhydrosiloxane), hydride terminated is set forth in
A diagram showing the synthesis of compound 2 is presented in
The synthesis of compound 1 can be verified by FT-IR (see example spectrum in
Analysis of the reaction products by 1H NMR (
A silicon NMR (J=200) of compound 1 (
The small downfield peak at about −8 ppm is representative of a hydrogen substituted ‘M’ (R3SiO) unit. Trimethyl substituted M units appear in the 5 to 10 ppm region of the spectrum, which is further evidence that the polysiloxane chain is hydrogen terminated. The downfield shift of the M unit occurs due to the lack of an oxygen atom, which deshields the Si nuclei.
In contrast, D unit silicon atoms comprise R2SiO. The cluster of peaks near about −21 ppm are representative of various D units. The inset shows peaks between about −20 and about −21 ppm, which are representative of D units that are adjacent to a D′ unit. The non-equivalence of the of the silicon atoms causes a slight downfield shift. The peaks at about −22 ppm symbolize repeating D units in a linear chain. The various peaks are a result of the different molecular weight chains in the sample. The upfield peaks at about −38 ppm are the D′ units within the polysiloxane chain and the same trend with the D units is observed with the D′ units; with the repeating units being slightly upfield of the different adjacent silicon atom peaks. In addition, the starting material 1,3,5,7-tetramethylcyclotetrasiloxane has reacted completely due to the fact that it would appear near −32 ppm in the spectrum.
Functionalization of compound 1 with cycloaliphatic epoxides and alkoxy silanes can be evaluated by FT-IR (see
The synthesis of the cycloaliphatic dichlorosilanes can be analyzed by FT-IR, proton NMR, and silicon NMR. The FT-IR spectra of cycloaliphatic dichlorosilanes (
The silane peak position can be predicted to a reasonable degree of accuracy if all of the substituents are known. By adding the wavelength values for each of the substituents (—Cl, —Cl, and —C5H9/C6H11) the location the Si—H peak can be found (see Table 1).
Generally, the proton NMR spectra of the cycloaliphatic dichlorosilanes (e.g.,
Silicon NMR can also be used to analyze the reaction product (see
Following distillation, silicon NMR (e.g., see
The mechanistic fragmentation of R4Si compounds, where R varies independently among alkyl, aryl, hydride, or the like can be studied.
The acid-liberating polymerization of dichlorosilanes is an equilibrium process; the reverse reaction may seriously affect the molecular weight and overall linearity of the polymerized product unless the acid is neutralized from the system. The substituents are usually resistant towards the HCl that is given off as a bi-product, such as dichlorodimethylsilane. However, if a Si—H group is present the HCl released will react with it according to the reaction below:
Si—H+HCl→Si—Cl+H2 (4)
and form an undesired Si—Cl, which can undergo hydrolysis and rather than a linear polysiloxane chain a substituted silsesquioxane is formed. Therefore, a saturated aqueous basic solution is used to neutralize the liberated acid.
The hydrolytic polymerization reaction products can be analyzed by FT-IR (e.g., see
Proton NMR spectra of the cyclic oligomers show trends similar to that of compound 1 (c.f.,
Silicon NMR (J=200) of the foregoing oligomers (
The data indicates that in some embodiments the average size of the cyclic structures is 15 units. In these embodiments, the cyclic chains' small size could be a result of diluted cycloaliphatic dichlorosilane precursors. Additionally, this could be the result of the dropwise method of adding silanes into the organic phase. Significantly, some embodiments of both the cyclopentyl and cyclohexyl oligomerization reactions produce approximately 10% small cyclic species having about three to four siloxane units. In some embodiments it is expected that molecular weights as high as about 4000 g/mol can be measured by GPC, which indicates a ring size of about 37 siloxane units.
According to proton NMR hydrosilating compounds 2 and 3 with a cycloalkene produces the corresponding cyclic oligomers of polydicycloaliphaticsiloxane (see
In some embodiments the cyclic oligomers of the polydicycloaliphaticsiloxanes can be combined with that of the polycycloaliphatichydrosiloxanes to yield poly(dicycloaliphaticsiloxane-co-cycloaliphatichydrosiloxane), hydride terminated (e.g., compounds 2 and 3). In one embodiment the procedure for preparing compounds 2 and 3 is analogous to that of compound 1 in that it uses an A-15 ion exchange resin, and an end capper for controlling molecular weight. Without the end capper the chains terminate predominantly by chance, which extends the lifetime of the reaction. In one embodiment, a % Si—H analysis of compounds 2 and 3 yields 11.5±1.1% Si—H and 10.8±0.9% Si—H. In some embodiments GPC indicates that both compounds 2 and 3 have molecular weights of about 35,000 g/mol.
In some embodiments photo differential scanning calorimetry (PDSC) can be used to study the relationship between polymer structure and reaction conditions. Particularly, some embodiments include photo-initiated cationic polymerization of functionalized polysiloxanes, which may yield highly crosslinked networks. Reaction rate can be measured by observing the rate at which heat is released from a polymerizing sample. In general, cationic polymerization kinetics varies from system to system and are often complex. While not wishing to be bound by any one theory, in many embodiments this variation and complexity is believed related to the dependency of the carbocationic center's reactivity on its proximity to a counterion. Additionally, in some embodiments a number of propagating species can be identified during polymerization such as ion pairs, solvated ions, and/or aggregates. Thus, a general kinetic equation is not available.
In some embodiments the pseudo steady-state approximation is invalid because the active centers do not undergo combination, as seen in free radical polymerizations. Consequently, in such embodiments the rates of initiation and termination are not equal, which renders the pseudo steady-state approximation inadequate to describe these reaction kinetics.
PDSC reaction runs can be carried out at various temperatures (e.g., −10° C., 25° C., and 60° C.) in studies directed to establishing an overall activation energy for a polymerization. Additionally, the relationship between exposure time and reaction rate can be determined by collecting data under various exposure time conditions (e.g., 1, 5, and 15 seconds).
The degree of cure, or conversion, can be estimated from the ratio of the amount of heat evolved from the partial conversion after time t at a specific temperature (Ht); to the total heat evolved from the reaction, ΔHp:
α=(Ht/ΔHp) (5)
If Equation (5) is a function of conversion, but not temperature, as is the case in photo-induced experiments, the activation energy, E, can be obtained by plotting ln[(1/ΔHp)(dH0/dt)] versus (1/T), where (dH0/dt) is the heat of polymerization at the maximum peak of the exotherm. Calculating the slope of this plot yields the activation energy (see Table 2). Photo-DSC experiments record the total heat of polymerization. Therefore, the activation energy is representative of an overall activation energy, which includes initiation, propagation, and termination:
ER=EI+EP−ET (6)
In order for the above equation to be valid, the production of active centers must continue throughout the reaction. In some embodiments adhering to this theory, the photosensitizers are not completely consumed until after the reaction has progressed beyond the peak maximum. Therefore, Equation (6) can be used to determine the overall activation energy for the photo-induced polymerization reaction.
According to some embodiments, the reaction rate and total conversion increases with increasing temperature. In such embodiments, this can be determined by obtaining exotherms exhibiting a larger integrated heat as temperature increases.
In some embodiments increasing the size of the substituent has a notable effect on the rate of polymerization and total conversion (see Table 2).
In general, longer exposures to UV light results in a higher conversion due to the production of more active species.
Synthesis of poly(dimethylsiloxane-co-methylhydrosiloxane), hydride terminated (compound 1). The synthesis diagram set forth in
Synthesis of cycloaliphatic dichlorosilane (see
Some embodiments include preparation of cycloaliphatic dichlorosilane. One example of such a preparation includes the following. A stainless steel bomb reactor is dried, sealed, evacuated, and cooled in a dry ice/acetone bath to about −80° C. The reactor is charged with chilled cycloalkene (e.g., about 5 g, or 30 mmol) and Wilkinson's catalyst (e.g., about 0.15 g or 0.16 mmol) and purged with nitrogen. Dichlorosilane (e.g., about 5 mL or 0.06 mol) is added to a calibrated tube and chilled to less than about −10° C. The dichlorosilane is condensed and then distilled into the bomb via a cannula in fluid communication with the bomb's inlet valve. Then the inlet valve is sealed and the bomb is allowed to warm to room temperature. The bomb is then heated for 24 hours at 120° C. by means of an oil bath. The bomb is allowed to cool before collecting the product. The reaction produces a clear, light yellow liquid, which can be distilled. After distillation, any residual unreacted cycloalkene and/or side products are removed under vacuum (e.g., at about 2 to 3 mmHg) to yield pure cycloaliphatic dichlorosilane (e.g., about 88% yield). The product can be characterized by 29Si NMR, 1H NMR, FT-IR, and/or mass spectroscopy.
General synthesis of cyclic oligomers of polycycloaliphatic-hydrosiloxane: Some embodiments include synthesis of one or more polycycloaliphatichydrosiloxanes. One example of such a synthesis includes the following. A saturated aqueous sodium bicarbonate (10 mL) and diethyl ether (5 mL) are added to a three-neck round bottom flask, equipped with a reflux condenser, nitrogen inlet/outlet ports, and a dropping funnel. A solution of cycloaliphatic dichlorosilane (e.g., about 4.43 g, or 0.03 mol) in ethyl ether (about 5 mL) is then added dropwise through the dropping funnel and the solution is stirred for several minutes at room temperature. The ether layer is separated, passed through a filter, and any remaining traces of ether are removed through vacuum distillation at about 3 to 5 mm Hg thereby yielding a clear, viscous oil. Weight average molecular weights (Mw) can be obtained for both the cyclopentyl and cyclohexyl substituted cyclic oligomers by gel permeation chromatography (GPC). Polycyclopentylhydrosiloxane oligomers prepared according to this example have a Mw of about 1,800 and a PDI of about 2.44. Additionally, polycyclohexylhydrosiloxane oligomers prepared according to this example have a Mw of about 2,230 and a PDI of about 2.53. The oligomers can be characterized by 29Si NMR, 1H NMR, FT-IR, and/or mass spectroscopy.
Synthesis of cyclic oliqomers of polydicycloaliphaticsiloxane: Some embodiments include synthesis of one or more polydicycloaliphaticsiloxanes. One example of such a synthesis includes the following. A single neck round bottom flask is equipped with a reflux condenser. The following components are added to the flask: cyclic oligomers of the desired polycycloaliphatichydrosiloxane (e.g., about 5 g), a cycloalkene (e.g., about 15 g), and Karstedt's catalyst (e.g., about 0.1 mL or 0.22 mmol). The reaction is held at 110° C. in an oil bath and magnetically stirred. The disappearance of the Si—H functionality is monitored through FT-IR and the disappearance of the peak at about 2160 cm−1 indicates that the reaction is complete. Generally, the reaction is substantially complete after about 48 hours. Any unreacted cycloalkenes can be removed under a vacuum of about 3 to 1 mm Hg thereby yielding a clear, viscous oil. The product(s) can be characterized by 29Si NMR, 1H NMR, FT-IR, and/or mass spectroscopy.
Cycloaliphatic epoxide and alkoxy silane functionalization of prepared poly(dialkyllsiloxane-co-alkylhydrosiloxane), hydride terminated polymers. Some embodiments include synthesis of one or more poly(dialkyllsiloxane-co-alkylhydrosiloxane). One example of such a synthesis includes the following. A three neck round bottom flask is equipped with a reflux condenser and nitrogen inlet/outlet ports. Next, the following components are added to the flask—compounds 1, 2, or 3 (e.g., about 30 g), 4-vinyl-1-cyclohexene diepoxide (e.g., about 20 g or 0.18 mol), vinyl triethoxysilane (e.g., about 2 g or 0.01 mol), and Wilkinson's catalyst (e.g., about 0.004 g or 4.3 μmol). Then, dry, distilled toluene (e.g., about 30 g) is added via a cannula. The reaction is then held at 75° C. in an oil bath and mechanically stirred under nitrogen. The disappearance of the Si—H functionality is monitored through FT-IR and the disappearance of the peak at about 2160 cm−1 indicates that the reaction is complete. Any solvent and/or unreacted starting materials are removed under a vacuum of about 3 to 5 mm Hg. Cycloaliphatic epoxide and alkoxy silane functionalization can be confirmed by 1H NMR, FT-IR, and/or titration.
The present invention provides, among other things, a variety of new material choices for applications such as membranes, films, aerospace materials, paints, and protective coatings. Furthermore, the present invention provides the capacity to tailor the siloxane polymer's pendant groups, which can be used to resolve miscibility and grafting issues by using groups similar in structure and/or polarity to a solvent. Additionally, some embodiments of the present invention can be used in connection with cycloaliphatic epoxides, alkoxy silane groups, and/or UV curable hybrid films to make membranes and/or or low coefficient of friction coatings. Still further, some embodiments provide the ability to adjust the glass transition temperature by varying the siloxane's pendant groups. Thus, some embodiments include lubricants for fibers, wetting agents for polyurethane foams, and temperature sensitive coagulating agents for latexes.
Although the invention has been described in detail with reference to particular examples and embodiments, the examples and embodiments contained herein are merely illustrative and are not an exhaustive list. Variations and modifications of the present invention will readily occur to those skilled in the art. The present invention includes all such modifications and equivalents. The claims alone are intended to set forth the limits of the present invention.
This application claims priority to previously filed U.S. Provisional Application No. 60/817,196, filed on Jun. 28, 2006, entitled “Process for Preparing Substituted Polysiloxane Coatings,” which is hereby incorporated by reference in its entirety.
Number | Date | Country | |
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60817196 | Jun 2006 | US |