Local Chain Dynamics in Poly(ester carbonate)s

Magic-angle spinning 13C{1H} recoupling NMR experiments have been performed on two series of poly(ester carbonate) block copolymers. The first series is based on bisphenol A blocks (B) and the second on tetramethylbisphenol A blocks (T). Three types of saturated-ring ester linkers were used, two of which contained bicyclic rings. The dynamic mechanical γ transitions of the B-series copolymers (but not the T-series copolymers) were shifted to higher temperatures. None of the ester linkers altered significantly the motional averaging at 300 K of 1H−13C dipolar couplings within either the B or T aromatic rings from the averaging observed for the corresponding polycarbonate homopolymers. All the B rings flip faster than 10 kHz at 300 K in the poly(ester carbonate)s, just as they do in polycarbonate itself, and none of the T rings flip, either in tetramethyl polycarbonate homopolymer or in the T-based poly(ester carbonate)s.