Miscibility of poly(epichlorohydrin)/poly(N-vinyl-2-pyrrolidone) blends investigated with high-resolution solid-state 13C 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 downfield shifting of the carbonyl resonance of PVP indicate intermolecular hydrogen bonding. H-1 T-1 rho relaxation rates monitored at the carbonyl group in PECH/ PVP blends were found as the weighted averages between the T-1 rho relaxation rate of the carbonyl group in pure PVP and that of the mobile alpha-hydrogen in pure PECH. A 1.3 ppm downfield shift was found for the carbonyl carbon of PVP in the C-13 CP/MAS/DD spectra. These observations provide evidence of strong hydrogen-bonding interactions between the carbonyl group and the alpha-hydrogen. The polymer components are completely miscible at the molecular level at all compositions. 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 into two peaks at 70.6 and 66.0 ppm. The upheld shifts of the methine and methylene peaks are due to strong dipolar interactions resulting in higher shielding of the C-13 nuclei. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.