BUNDLE DESCRIPTION OF PACKING AND DYNAMICS IN POLYCARBONATE HOMOPOLYMERS, COPOLYMERS, AND BLENDS

Dipolar-rotational spin-echo C-13 NMR spectra at 15.1 MHz have been ob tained for 12 homopolymers, copolymers, and blends of polycarbonate, p oly(ether carbonate), poly(ether sulfone), dimethyl polycarbonate, and tetramethyl polycarbonate. The spectra were used to determine the fra ction of nonmethylated phenylene rings that are blocked from undergoin g pi flips faster than 10 kHz at 300 K. This fraction is interpreted i n terms of a simple two-chain bundle packing model in which empiricall y determined steric parameters specify the interchain interactions bet ween flexible chain linkers and rigid chain extenders. The success of this bundle description suggests that the glassy state for all of thes e polycarbonate-like systems has local mainchain orientational order.