A solid-state C-13 NMR study on phase heterogeneity in the miscible blend of amorphous poly(benzyl methacrylate) with semicrystalline poly(ethylene oxide)

The rotating-frame spin-lattice relaxation time for protons, T-1p,(H-1), wa s measured indirectly from C-13 CP/MAS/DD NMR to probe possible molecular s cales of heterogeneity in the miscible poly(benzyl methacrylate) (PBzMA)/po ly(ethylene oxide) (PEO) blend over the whole composition range. According to the NMR results, only one phase was observed for the blends in which the PEO component is less than 16% (w/w). This miscible amorphous phase with P BzMA and PEO chains was mixed at the molecular level. Three phases were det ected for the blends with PEO component >16%, containing one miscible homog enous PBzMA-rich phase, one constrained PEO phase and one crystalline PEO p hase. The PEO component asymptotically increases in the miscible homogenous PBzMA-rich phase as the PEO composition increases. NMR analysis helped res olve the complex phase domains in the PBzMA/PEO blend that is composed of a n amorphous mixture of PBzMA/PEO and crystalline PEO spherulite regions. Th e intra- and inter-lamellar domains in the PEO spherulites are influenced a nd complicated by the surrounding amorphous PBzMA/PEO mixture with varying composition. (C) 2001 Elsevier Science Ltd. All rights reserved.