2-DIMENSIONAL NMR CHARACTERIZATION OF SHORT-RANGE ORDER IN A MISCIBLE BLEND OF POLYSTYRENE AND POLY(2,6-DIMETHYL-P-PHENYLENE OXIDE)

Measurements of H-1 NMR spin diffusion have been obtained for a miscible polymer blend of deuterated polystyrene (PS-d5) and poly(2,6-dimethyl-p-phenylene oxide) (PPO) through the use of a new solid-state heteronuclear correlation (HETCOR) two-dimensional (2D) method. Proton spin-diffusion data were used to examine local ordering of PS-d5 and PPO segments and to experimentally measure the number of heterosegmental contacts. The data were compared with theoretical results obtained from a lattice simulation based on Monte Carlo methods. Solid-state 2D HETCOR spectra were obtained through the use of multiple-pulse selective cross-polarization (WIM-24) and with BB-12 C-13 decoupling during the evolution period. An additional mixing period was inserted for H-1 spin diffusion. This approach provided greater resolution than the previous homonuclear H-1-H-1 method while retaining the former method's selectivity for closely spaced protons. Consequently, a greater variety of polymer mixtures is now accessible for study.