Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. For liquid crystal displays used in the displays of smart phones, tablet PCs, liquid crystal televisions, and the like, zero birefringence is required and achieved by adding additives. The group of Tadahisa IWATA at the University of Tokyo found that pullulan acetate, a chemical derivative of pullulan produced by Aureobasidium pullulans, showed no birefringence and could be casted into polymer films which were highly transparent and showed no birefringence.

JST news release, April 18, 2017