Journal of Polymer Science Part B: Polymer Physics, Vol.36, No.13, 2291-2300, 1998
Examination of miscibility at molecular level of poly(hydroxyether of bisphenol A) poly(N-vinyl pyrrolidone) blends by cross-polarization magic angle spinning C-13 nuclear magnetic resonance spectroscopy
The miscibility of poly(hydroxyether of bisphenol A) (phenoxy) and poly(N-vinyl pyrrolidone) (PVP) was investigated by differential scanning calorimetry (DSC) and high-resolution solid-state nuclear magnetic resonance (NMR) techniques. The DSC studies showed that the phenoxy/PVP blends have a single, composition-dependent glass transition temperature (T-g). The S-shaped. T-g-composition curve of the phenoxy/PVP blends was reported, which is indicative of the strong intermolecular hydrogen-bonding interactions. To examine the :miscibility of the system at molecular level, high-resolution solid-state C-13 nuclear magnetic resonance (NMR) technique was employed. Upon adding phenoxy to system, the chemical shift of carbonyl carbon resonance of PVP was observed to shift downfield by 1.6 ppm in the C-13 cross-polarization (CP)/magic angle spinning (MAS) together with the high-power dipolar decoupling (DD) spectra when the concentration of phenoxy is 90 wt %. The observation was responsible for the formation of intermolecular hydrogen bonding. The proton spin lattice relaxation time T-1(H) and the proton spin-lattice relaxation time in the rotating frame T-1 rho(H) were measured as a, function of the blend composition. The T-1(H) result was in good agreement with the thermal analysis, i.e., the blends are completely homogeneous on the scale of 20 similar to 30 nm. The six results of T-1 rho(H) further indicated that the blends were homogeneous on the scale of 40 similar to 50 Angstrom.
Keywords:SOLID-STATE NMR;GLASS-TRANSITION TEMPERATURES;POLY(METHYL METHACRYLATE);POLYMER BLENDS;POLYIMIDE BLENDS;EPOXY-RESINS;COMPATIBILITY;POLY(VINYLPYRROLIDONE);COPOLYMERS;RELAXATION