Transparent Zero-Birefringence Polymers

Birefringence is caused by orientation of polymer chains during injection-molding and extrusion and it is a disadvantage in optical systems such as lenses, compact disks, waveguides. We propose new transparent zero-birefringence polymers for any degree of orientation of polymer chains, which are obtained by the following two methods. One is random copolymerization of negatively and positively birefringent monomers. The other is doping of a small amount of large anisotropic molecules into a polymer matrix to compensate the birefringence caused by the orientation of polymer chains. Zero-birefringence polymers synthesized by these two methods have low scattering loss, which is comparable with that of pure poly(methyl methacrylate) (PMMA), and had no observable microscopic heterogeneous structures.