| abstract |
A method of controlling positive birefringence in an optical compensation film (positive C plate) having a high positive birefringence over a wavelength range of 400 nm <λ <800 nm is provided. The method includes selecting a polymer having an optically anisotropic subunit (OASU) that exhibits a bracing effect, where the OASU may be an aromatic ring substituted with a disc, mesogen, or birefringence enhancing substituent. The method further includes processing the polymer by solution casting to obtain a polymer film having a high birefringence without the need for stretching, photopolymerization or other processes. These optical compensation films can be used in LCDs, in particular IPS-LCDs. |