Abstract: Films with optical transmittance of >80% between 400 and 750 nm and with coefficient of thermal expansion less than 20 ppm/° C. are prepared from aromatic polyamides that are soluble in polar organic solvents yet have glass transition temperatures >300° C. The films are cross-linked in the solid state by heating at elevated temperatures for short periods of time in the presence of multifunctional epoxides. Surprisingly, the optical and thermal properties of the films do not change significantly during the curing process. The temperature required for the crosslinking process to take place can be reduced by the presence of a few free, pendant carboxyl groups along the polyamide backbones. The films are useful as flexible substrates for electronic displays and photovoltaic devices.

Abstract: A class of soluble poly(aryletherimides) (PAEIs) having flexible backbones, useful in the manufacture of polymeric optical films are disclosed. The poly(aryletherimides) are dissolved in organic solvents, such as ketones and ketone solvent mixtures and coated on variety of substrates such as triacetyl cellulose (TAC), to form clear thin-layer films which display negative birefringence. The thin films can serve as compensation layers in liquid crystal displays (LCDs), and can be combined with other types of optical films, such as polarizers, brightness enhancement films, or other compensation films, to from multi-layered films that are especially useful in the manufacture of LCDs.