Synthesis and Properties of Polyimidothioether and Polyimide-Silica Hybrid Optical Films
Date Issued
2012
Date
2012
Author(s)
Tung, Wei-Yao
Abstract
Polyimides are high performance and functional polymers used in different fields. However, the development of polimides with high refractive index, optical transmittance, and superior thermal-mechanical properties remain challenges. In this thesis, high refractive index and high optical transparency polyimides and their optical films were synthesized by molecular design and hybrid technology as following:
In this study, we synthesized the two dithiol monomers and then polymerized with bismaleimide by Michael addition under low temperature to get the colorless polyimidothioether, PITEDT and PITEMD.The materials have high refractive index and moderate Abbe’s number because of the high sulfur content and aromatic imide functional group in these polyimidothioether. The prepared optical thin films of these two polymers have high refractive index (> 1.71), excellent transparency (> 95% at 400nm) and moderate Abbe’s number (> 22). Secondly, three colorless polyimides with hydroxyl group, 6FOXPI, 6F6FPI and 6FDBPI. The hybrid optical flexible optical films of these polyimides with different silica oxide content have successfully synthesized.In this study, hexafluoroisopropylidene, ether and t-butyl groups are used to increase the free volume of the polyimides, thereby improving the optical transparency, organic solubility and flexibility. Tetramethyl orthosilicate was used to form a covalent bond between silicon oxide and the hydroxyl group of the polyimides. By this method, it was found that the particle were well dispersed and the size of silicon oxide is 8~12nm which can avoid the light scattering. By forming the intramolecular coupling crosslink bond between the silica and polyimides, these hybrid films have better thermal and mechanical properties. These hybrid optical films have much lower coefficient of thermal expansion (< 55 ppm/oC), high TS (> 300 oC) and high Td (> 400 oC) and good optical transparency (> 80% at 400nm, thickness > 25 μm ).
In this study, we synthesized the two dithiol monomers and then polymerized with bismaleimide by Michael addition under low temperature to get the colorless polyimidothioether, PITEDT and PITEMD.The materials have high refractive index and moderate Abbe’s number because of the high sulfur content and aromatic imide functional group in these polyimidothioether. The prepared optical thin films of these two polymers have high refractive index (> 1.71), excellent transparency (> 95% at 400nm) and moderate Abbe’s number (> 22). Secondly, three colorless polyimides with hydroxyl group, 6FOXPI, 6F6FPI and 6FDBPI. The hybrid optical flexible optical films of these polyimides with different silica oxide content have successfully synthesized.In this study, hexafluoroisopropylidene, ether and t-butyl groups are used to increase the free volume of the polyimides, thereby improving the optical transparency, organic solubility and flexibility. Tetramethyl orthosilicate was used to form a covalent bond between silicon oxide and the hydroxyl group of the polyimides. By this method, it was found that the particle were well dispersed and the size of silicon oxide is 8~12nm which can avoid the light scattering. By forming the intramolecular coupling crosslink bond between the silica and polyimides, these hybrid films have better thermal and mechanical properties. These hybrid optical films have much lower coefficient of thermal expansion (< 55 ppm/oC), high TS (> 300 oC) and high Td (> 400 oC) and good optical transparency (> 80% at 400nm, thickness > 25 μm ).
Subjects
Polyimidothioether
Polyimide
Optical films
Polyimide-Silica hybrid
Type
thesis
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