Zero-birefringence polymer doped with a nano size birefringent crystal

We reported the "birefringent crystal dopant method" in order to compensate the orientational birefringence of polymers. In this method, a birefringent inorganic crystal is homogeneously doped in a polymer and compensates the birefringence of the polymer. Strontium carbonate (SrCO ₃) was selected for this purpose because it has a large birefringence and a rod-like shape. SrCO₃ was synthesized and doped into a poly(MMA/BzMA=78/22(wt/wt)) (78/22 polymer) film and the film was drawn above glass transition temperature (T_g). The orientational birefringence of the drawn film at a wavelength of 633 nm was compensated by doping with 0.3 wt% of SrCO₃ without losing its transparency and thermostability.