SBIR Phase I: Thermally Stable, Flexible Substrates for Flat Panel Displays

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This Small Business Innovation Research Phase I project will establish the feasibility of producing a flexible, highly transparent polyimide film that is thermally stable, has a high glass transition, displays near zero birefringence and a low coefficient of thermal expansion (CTE). This material is designed for use as a flexible flat panel display substrate. No available material displays all of these properties. The key technical problem will be the design of a molecular architecture that balances low film birefringence, which generally requires a flexible polymer, and CTE, which generally requires a rigid polymer. This apparent paradox will be addressed through the preparation of a rigid copolymer that contains both positive and negative birefringent units. The ratio of these units will be varied to obtain zero birefringence in a film of the material. Since solution casting of the rigid copolymer will result in isotropic, in-plane chain orientation, these copolymer films should display low CTEs as well as low birefringences. Structure property relationships between the polymer architecture and the film properties will be developed. This will further the scientific understanding of the interplay between molecular architecture and material properties. The broader/commercial impact of this project includes enhanced scientific and technological understanding of these new materials which will enable the next generation of display technologies which includes flexible liquid crystal (LC) displays. Currently the LC display market alone is a hundred-billion dollar a year industry. Flexible displays would consume a large fraction of that market as well as open-up new markets for portable flexible displays. These include conformable displays that can be integrated onto clothing, flexible e-paper and e-book displays, displays for smartcards, and a host of other new applications. These new devices would dramatically impact daily life, by decreasing the cost and increasing accessibility and portability of streaming information. Current flexible substrates are either non-transparent, and so are limited to reflection mode displays, or have low processing temperatures which dramatically restricts their performance as well as number and range of display applications. If successful, the substrates to be developed under this project is expected to enable, for the first time, high temperature processing of flexible LC displays, opening the potential of new display devices of higher performance.