Patent Application
20090104362
1. Field of Invention
The present invention relates to an organic-inorganic hybrid material. More particularly, an organic-inorganic hybrid material and a hybrid film derived therefrom and methods preparing the same by hybrid process without adding any chelating agent are disclosed.
2. Description of Related Art
Organic-inorganic hybrid materials possess not only the advantages of organic materials, such as processability and flexibility, but also the advantages of inorganic materials, like high mechanical strength and high thermal properties, and hence are studied internationally and are widely applied in various fields. In general, a hybrid material is prepared by mixing an organic material and an inorganic material, which are associated by molecular forces therebetween, such as, for example, London-van der Waals force or hydrogen bonding, on a nanometer scale. Therefore, the hybrid material is formed without phase separation in the macroscopic view, and further combines the properties of the organic material and the inorganic material.
Due to the poor thermal properties of organic materials, organic-inorganic hybrid materials cannot be prepared in a conventional ceramic-manufacturing process. Instead, a sol-gel process is usually adopted to fabricate organic-inorganic hybrid materials. Sol-gel process including a hydrolysis step and a condensation step performed at a low temperature. Consequently, organic materials can be introduced into inorganic materials without degradation.
The organic-inorganic hybrid materials prepared by the sol-gel process, however, are easily influenced by surrounding conditions, such as, for instance, temperature or humidity. As a result, the organic-inorganic hybrid materials tend to age, which decreases the shelf life thereof. Additionally, the organic-inorganic hybrid materials with a nanometer dimension incline to aggregate with one another. To stabilize the properties and the sizes of the organic-inorganic hybrid materials, chelating agents are required in preparing the same. The chelating agents are, for example, methacrylic acid, acetic acid, and acetyl acetone.
On the other hand, the solid content of the organic-inorganic hybrid materials prepared by the sol-gel process is usually around 20% to 30%, of which the viscosity is not high enough for preparing a thick hybrid film. Unfortunately, raising the solid content by increasing reaction time and reactant concentrations directly results in gelation of the organic-inorganic hybrid materials. Moreover, phase separation occurs if the viscosity of the organic-inorganic hybrid materials is increased by adding another polymer solution with higher viscosity.
According to an embodiment of this invention, a functionalized organic-inorganic hybrid material and a preparation method thereof are provided. An organic material and an inorganic material are separately mixed with corresponding solvents, followed by mixing the solvents and heating the same for a period of time to form a functionalized organic-inorganic hybrid material. The inorganic material is a metal alkoxide or silicon alkoxide wherein the valence of the metal atom or silicon atom therein is greater than zero, while the organic material is an organically modified Si-alkoxide. The interaction between the organic-inorganic hybrid materials is effectively reduced, which prevents the organic-inorganic hybrid materials from aggregating with one another, by selecting proper solvents at the beginning of preparation. Therefore, the functionalized organic-inorganic hybrid material with a stable nanometer dimension is formed by means of the selected solvents instead of any chelating agents.
According to another embodiment of this invention, a method for preparing a thick hybrid film derived from a functionalized organic-inorganic hybrid material is provided. The solid content of a functionalized organic-inorganic hybrid material is dramatically raised by transferring the hybrid material into a selected solvent. A thick and uniform film is then formed more easily, since the solid content of the organic-inorganic hybrid material has been increased. Hence, the organic-inorganic hybrid material after being transferred can be directly used to fabricate a thick film with no need of other adhesives, like polymer solution with higher viscosity.
The foregoing aspects, as well as many of the attendant advantages and features of this invention will become more apparent by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
It is found that an organic-inorganic hybrid material with a stable dimension on a nanometer scale is prepared with no need of chelating agents, if the stability of a reactive solution is properly controlled according to the following equations at the beginning of preparation.
Equation (1) represents the attraction energy (Vatt) between two spherical particles (medium 1) dispersed in a medium 3, where A13 is the Hamaker constant and H(x, y) is the Hamaker function, which depends on the inter-particle distance and on the particle radius. An approximate expression for A13 is given by equation (2), where ∈1 and ∈3 are the dielectric constants of the media, n1 and n3 are their refractive indexes in the visible range, νe is the absorption frequency of the media assumed to be the same for both of them, k is the Boltzmann constant (1.38×10−23 J·K−1), T is the absolute temperature, and h is the Planck's constant (6.626×10−34 J·s).
According to these equations, the interaction between particles is dependent on the properties of a medium where the particles are dispersed. Consequently, the attraction energy between particles is reduced if an adequate medium is selected; the particles are thus less attracted to one another and aggregate less. Therefore, particles with stable dimensions are obtained without using any chelating agents. By this principle, a functionalized organic-inorganic hybrid material, a method for preparing the same, and a thick hybrid film derived therefrom in accordance with the embodiments of the present invention are disclosed in detail as follows, taken in conjunction with the accompanying drawings.
One aspect of the present invention is to provide a metal alkoxide/silicon alkoxide and an organically modified Si-alkoxide having a predetermined functional group as precursors to form a functionalized organic-inorganic hybrid material. Additionally, solvents are selected according to the principle mentioned above before preparing the material. As a result, stable reactive surroundings for the material are provided at the beginning of preparation.
The metal alkoxide or silicon alkoxide can be formulated as M(OR)x, where M is a metal atom or silicon atom, x is the valence of M, and R represents C1-C12 alkyl group. Further, the valence of the metal atom (i.e. the difference between the coordination number and the valence of M) is greater than zero. The metal atom is, for example, titanium (Ti), zirconium (Zr), germanium (Ge), tin (Sn), or zinc (Zn). The aforesaid alkoxide includes zirconium butoxide (Zr(OBu)4), zirconium proxide (Zr(OPr)4), germanium (IV) ethoxide (Ge(OC2H5)4), germanium (IV) isopropoxide (Ge[OCH(CH3)2]4), titanium ethoxide (Ti(OC2H5)4), tertabutyl orthotitanate (Ti(OC4H9)4), tin (IV) tert-butoxide (Sn(OC4H9)4), tetraethyl orthosilicate (Si(OC2H5)4), zinc acetate dihydrate (Zn(CH3COO)2), or aluminum sec-butoxide (Al[OC(CH3)2]3), and zirconium butoxide is preferably used in the embodiment. Furthermore, the organically modified Si-alkoxide can be expressed as R1Si(OR)3 or R1R2Si(OR)2, where R represents C1-C12 alkyl, and R1 and R2 are hydrocarbyl groups that may be different or the same. The predetermined functional group (R1 or R2) may be an epoxy group or an amine group (—NH), or an unsaturated functional group, such as a vinyl group, an acryl group, or a photosensitive derivative thereof. Moreover, methacryloxypropyl tri-methoxysilane (MPTMS) is preferably used in the embodiment.
Reference is made to
The resultant material is a transparent solution, which also implies that the resultant particles are on a nanometer (nm) scale and are well dispersed in the solvents. The Fourier Transformation infrared (FTIR) spectrum of the particles is shown in
Further, the attraction energy (A13) of THF as calculated by the aforementioned equation (2) is 11.1 or so. As a result, the interaction between the particles is decreased by THF, which prevents the particles from attracting one another and aggregating. Therefore, an organic-inorganic hybrid particle with stable dimensions is prepared through adequate solvents. Moreover, THF is only an exemplary solvent, and is not intended to limit the invention. Other solvents that provide stable reactive surroundings, for instance, toluene (A13 is about 12.1) or propylene glycol monoether acetate (PMAc) (A13 is about 9.6), are also used to prepare an organic-inorganic hybrid material with stable dimensions.
On the other hand, the aforenamed precursors and the proportions thereof are merely in favor of illustrating the embodiment. It is appreciated that any substitutes, although not described or shown herein, which embody the principles of the invention, are included within the spirit and scope of the invention. For instance, an organic-inorganic hybrid material having an epoxy group on a nanometer scale is formed through 3-glycidoxypropyl trimethoxysilane (GLYMO), in the case where solvents are appropriately selected at the beginning of preparation.
In this embodiment, an organic-inorganic hybrid material is formed in alcohol under the same preliminary conditions as those in embodiment 1. The material in alcohol is further compared with materials formed in different solvents, which results are listed in Table 1.
It is found from Table 1 that, a transparent solution of organic-inorganic hybrid nanoparticles are obtained if an adequate solvent is selected. Consequently, nanoparticles attract one another and aggregate less, and thus have stable sizes, because solvents decrease the interaction between particles. On the contrary, larger particles are given in alcohol, and the resultant solution is opaque. Furthermore, the dielectric constant of solvents is preferably smaller than 10.
The organic-inorganic hybrid material can be further used for preparing a thick hybrid film or a thin hybrid film. In the following embodiment, preparation of a thick hybrid film is provided.
For preparing a thick hybrid film, the solid content of an organic-inorganic hybrid material is increased by transferring the same into another solvent in accordance with the present invention. The organic-inorganic hybrid material of Embodiment 1 herein is only an example to describe the process for convenience, which is not proposed to limit the invention.
Reference is made to
In view of the above, a thick and uniform hybrid film is derived directly from a transferred organic-inorganic hybrid material in accordance with the embodiment. Consequently, no binder is required, and no phase separation occurs. Additionally, the thickness of a hybrid film can be controlled by adjusting the solid content of a organic-inorganic hybrid material. Further, the transmission of the hybrid film coated on a glass is above 90% in the visible range of 400 nm to 700 nm and at wavelengths of 1310 nm and 1550 nm. The baking temperature or species of the initiator and the third solvent are exemplary descriptions only, and are not proposed to limit the invention.
In the following embodiments of the present invention, other metal alkoxides or silicon alkoxide, instead of zirconium butoxide, were also provided to prepare the functionalized organic-inorganic hybrid material. The metal alkoxides or silicon alkoxide used were germanium (IV) ethoxide (Ge(OC2H5)4), germanium (IV) isopropoxide (Ge[OCH(CH3)2]4), titanium ethoxide (Ti(OC2H5)4), tertabutyl orthotitanate (Ti(OC4H9)4), tin (IV) tert-butoxide (Sn(OC4H9)4), zirconium (IV) propoxide (Zr(OC3H4)4), tetraethyl orthosilicate (Si(OC2H5)4), zinc acetate dihydrate (Zn(CH3COO)2), or aluminum sec-butoxide (Al[OC(CH3)2]3).
In general, all the procedures of preparing an organic-inorganic hybrid material were the same as described in embodiment 1. Again, MPTMS was used as the organically modified Si-alkoxide, and THF was used as the first and the second solvent. All of the reactants were listed in the following Table 2.
In Table 2, the amounts of metal or silicon alkoxides is more than the amount used in prior arts, since the solvent is selected according to the results of Embodiment 2 above. The molar ratio of metal or silicon alkoxides to MTPMS (the organically modified Si-aloxide) can be raised to at least 0.35 without any aggregation, although no chelating agent is added.
The particle scale of resultant organic-inorganic hybrid materials prepared above is also detected. The transmission electron microscopy (TEM) pictures of the particles in sample 2, 5, 6, 7, 9, and 4 are shown in
Next, the photosensitive organic-inorganic hybrid material prepared above was transferred into a third solvent, propylene glycol monoether acetate (PMAc). Each sample's solid content was detected before and after transferring into PMAc. The results were also shown in Table 2. By comparing solid content of each sample in Table 2, it was noticed that the solid content of the organic-inorganic hybrid material was increased by transferring the organic-inorganic hybrid material form THF to PMAc. Taking sample 1 for example, the solid content was 48.1% in THF. After transferring sample 1 from THF to PMAc, the solid content was increased to 68.2%. Accordingly, the solid content of the organic-inorganic hybrid material can be raised at least 40% by transferring organic-inorganic hybrid material from THF to PMAc. Therefore, a thick and uniform film can be formed more easily, since the solid content of the organic-inorganic hybrid material has been increased.
In the embodiment of the present invention, by using the functionalized organic-inorganic hybrid material prepared in embodiment 4, the thick hybrid films were prepared and then the transmission of the hybrid films were detected. All the procedures of preparing the thick hybrid films were the same as described in embodiment 3. There are varieties of photo initiators can be used, such as CHEMCURE481, ITX907, Irgacure 184, Irgacure 907, etc. The amount of the photo initiators added is 1-5% of the solid content of MPTMS. In this embodiment, the photo initiator used was CHEMCURE481, and the amount of photo initiator added is 3% on the substrate. The transmission testing results were shown in Table 3 and
According to the transmission results shown in Table 3 and
The photo- or thermal-sensitivity of organic-inorganic hybrid materials is highly related to the predetermined functional group of the organically modified Si-alkoxide. Since MPTMS is with a photosensitive functional group, the organic-inorganic hybrid materials prepared by MPTMS above are photosensitive. In this embodiment of the present invention, three thermal-sensitive organic-inorganic hybrid materials were provided by using 3-glycidoxypropyl tri-methoxysilane (GPTS) comprising a thermal sensitive functional group. Basically, the process of preparing thermal-sensitive hybrid materials was the same as described in embodiment 1. All the reactants of the three samples were listed in the following Table 4. Instead of MPTMS, the organically modified Si-alkoxide used was GPTS. Furthermore, not only THF but also MeOH could be used as the first solvent and second solvent, and the acid added were either HCl or HNO3.
The thermal-sensitive organic-inorganic hybrid materials above can be used for preparing a hybrid film as well. First, the thermal-sensitive organic-inorganic hybrid material is mixed with epoxy merchandise, such as epoxy 4221, and then amine hardener is added. Next, as shown in
According to the aforementioned embodiments of the present invention, a functionalized organic-inorganic hybrid material is prepared without any chelating agents in selected solvents. The resultant organic-inorganic hybrid particles are on a nanometer scale, and are stably dispersed in the selected solvents. On the other hand, a thick hybrid film is fabricated by means of the organic-inorganic hybrid material of which solid content is effectively increased by transferring the same into another solvent.
While the invention has been particularly shown and described with reference to the embodiments thereof, these are, of course, merely examples to help clarify the invention and are not intended to limit the invention. It will be understood by those skilled in the art that various changes, modifications, and alterations in form and details may be made therein without departing from the spirit and scope of the invention, as set forth in the following claims.
This application is a continuation-in-part of U.S. application Ser. No. 10/889,306, filed on Jul. 12, 2004, hereby incorporated by reference as it fully set forth herein.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10889306 | Jul 2004 | US |
| Child | 12283075 | US |
