MAPPING OF MOTIONAL HETEROGENEITY IN ORGANIC-INORGANIC NANOCOMPOSITE GELS

Organic-inorganic nanocomposite gels comprising poly(ethyleneoxide) ch ains grafted between silica particles have been studied by electron pa ramagnetic and nuclear magnetic resonances. Motional heterogeneity has been investigated as a function of gelation and drying by paramagneti c probes dissolved in the organic phase or grafted onto the inorganic nodes. The organic phase exhibits marked variations in dynamic behavio r with the liquidlike mobility of the polymer chains strongly hindered at the silica nodes. The conclusions of the EPR study are confirmed b y liquid- and solid-state carbon-13 NMR measurements. (C) 1996 John Wi ley & Sons, Inc.