Design, Synthesis, and Properties of Polyimides and Their Hybrid Materials for Optical Applications
Date Issued
2010
Date
2010
Author(s)
Wang, Yu-Wen
Abstract
Organic–inorganic hybrid materials have been extensively studied recently since their molecular tailing properties could produce new functionalities. Such hybrid materials have been widely investigated for advanced optical applications, such as high refractive materials, non-linear optical materials, optical waveguide, and protective layer materials. In this study, the objectives are to synthesize hybrid nanocomposites of polyimide / inorganic hybrid and explore the optical application, including optical waveguides, high refractive index films, and antireflective films.
Two classes of photosensitive-silica hybrid materials are synthesized and characterized. In Chapter 2, the volume shrinkage during imidization is largely reduced by introducing coupling agent and inorganic moiety in the conventional ionic salt photosensitive polyimide. The volume shrinkage during the thermal curing imidization is reduced from 28.1 % to 5.9 %, and this approach also increases the resolution of patterns and reduces the optical loss as well. In Chapter 3, photosensitive colorless polyimide-silica hybrid materials with more inorganic content are not only have lower volume shrinkage during thermal imidization, but also exhibit transparency in the visible region. The hybrid film could be patterned by a direct lithographic process and developed to kinds of patterns and have the application in different optical waveguides.
Colorless polyimide-silica and polyimide-titania hybrid thin films are described in Chapter 4. The modified titania precursors are added in the polyimide matrix to form the polyimide-titania hybrid materials. Furthermore, hydrothermal treatment was used to induce condensation and crystallization of amorphous titania at a relative low temperature, thus enhance the refractive indices also. The experimental results suggest that transparent and tunable refractive indices (1.550-1.847 at 633nm) polyimide-silica/titania hybrid thin films were prepared. A three-layer anti-reflective coating based on the prepared hybrid films was designed and processed on glass and polymer film substrates with a reflectance of less than 0.5 % in the visible range.
The above polyimide-inorganic hybrid materials exhibit superior optical characteristics than their parent polymers. Such materials would be of interest in various optical and optoelectronic devices, such as antireflective films and optical waveguides…etc.
Subjects
Polyimide
Hybrid materials
Photosensitive
Colorless
Optical properties
Optical waveguide
Antireflective coatings
Type
thesis
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