| 主权项 |
1. A uniaxially stretched polymer film having a refractive index profile of nx<ny≦nz, which satisfies the relation of ny−nx>0.001, wherein nx is the in-plane refractive index parallel to the film stretching direction, ny is the in-plane refractive index perpendicular to nx, and nz is the thickness refractive index, where the stretched polymer film is prepared by stretching an unstretched polymer film made from a polymer capable of being solution cast into a positive C plate with a refractive index profile of nx=ny<nz and the relation of nz−(nx+ny)/2>0.002, wherein the unstretched polymer film is prepared by solution casting a polymer solution comprising a polymer having a moiety of wherein R1, R2, and R3 are each independently hydrogen atoms, alkyl groups, substituted alkyl groups, or halogens, wherein OASU is an optically anisotropic sub-unit that is a substituted aromatic group, a disk-like group, or a mesogen, and wherein OASU is attached to the polymer backbone through a single covalent bond. |
