Anisotropic Molecule Dopant Method for Synthesizing a Zero-Birefringence Polymer

We have demonstrated the anisotropic molecule dopant method for synthesizing a zero-birefringence polymer that showed no orientational birefringence at any orientation degree of polymer chains. In this method, rod-like molecules such as trans-stilbene having opposite polarizability anisotropy to that of a host polymer were chosen to compensate orientational birefringence. Orientational birefringence of poly(methyl methacrylate) was completely compensated by doping with some types of anisotropic molecules. Compensation of orientational birefringence for drawn films of the zero-birefringence polymers was analyzed by the rotating parallel nicols method, and orientation functions for polymer main chains and the anisotropic molecules were determined by IR dichroism, which showed that both the polymer chains and the anisotropic molecules were oriented almost equivalently in the drawing process resulting in complete compensation at any draw ratio. Furthermore, the high transparency (37.2 dB/km) of the zero-birefringence polymer was confirmed by light scattering measurements.