Birefringent properties of poly(phosphonate)s and poly(thiophosphonate)s derived from various bisphenols

The birefringent properties of poly(phosphonate)s and poly(thiophosphonate)s possessing various bisphenol structures were investigated. The CR values (orientational birefringence) of the poly(phosphonate)s and the poly(thiophosphonate)s range from ？0.3？×？10？9 to + 1.3？×？10？9？Pa？1 and from ？0.6？×？10？9 to +？0.8？×？10？9？Pa？1, respectively, which are lower than those of the corresponding bisphenol A-based polymers. The CD values (photoelastic birefringence), which range from +？4.0？×？10？11 to +？4.9？×？10？11？Pa？1, are also lower than those of the corresponding bisphenol A-based polymers