MISCIBILITY OF POLY(EPICHLOROHYDRIN) POLY(N-VINYL-2-PYRROLIDONE) BLENDS INVESTIGATED WITH HIGH-RESOLUTION SOLID-STATE C-13 NMR/

The miscibility of poly(epichlorohydrin)/poly(N-vinyl-2-pyrrolidone) ( PECH/PVP) blends was investigated by C-13 cross-polarization combined with magic-angle sample spinning and high-power dipolar decoupling (CP / MAS/DD) techniques. Intermolecular cross-polarization and the downfi eld shifting of the carbonyl resonance of PVP indicate intermolecular hydrogen bonding. H-1 T-1 rho relaxation rates monitored at the carbon yl group in PECH/ PVP blends were found as the weighted averages betwe en the T-1 rho relaxation rate of the carbonyl group in pure PVP and t hat of the mobile alpha-hydrogen in pure PECH. A 1.3 ppm downfield shi ft was found for the carbonyl carbon of PVP in the C-13 CP/MAS/DD spec tra. These observations provide evidence of strong hydrogen-bonding in teractions between the carbonyl group and the alpha-hydrogen. The poly mer components are completely miscible at the molecular level at all c ompositions. In addition, the methine beta-C of PECH is split into two peaks at 80.0 and 76.2 ppm and the methylene gamma-C is also split in to two peaks at 70.6 and 66.0 ppm. The upheld shifts of the methine an d methylene peaks are due to strong dipolar interactions resulting in higher shielding of the C-13 nuclei. (C) 1998 Published by Elsevier Sc ience Ltd. All rights reserved.