Mapping of motional heterogeneity in organic-Inorganic nanocomposite gels

Abstract

Organic‐inorganic nanocomposite gels comprising poly(ethyleneoxide) chains grafted between silica particles have been studied by electron paramagnetic and nuclear magnetic resonances. Motional heterogeneity has been investigated as a function of gelation and drying by paramagnetic probes dissolved in the organic phase or grafted onto the inorganic nodes. The organic phase exhibits marked variations in dynamic behavior with the liquid‐like mobility of the polymer chains strongly hindered at the silica nodes. The conclusions of the EPR study are confirmed by liquid‐ and solid‐state carbon‐13 NMR measurements. © 1996 John Wiley & Sons, Inc.

Polymer-Silicate Nanocomposites: Model Systems for Confined Polymers and Polymer Brushes

“…Similar results of strong hindering of polymer mobility by surfaces have also been found by Brik et al [37]. They studied the motional heterogeneity of PEO grafted between silica particles using electron paramagnetic resonance as well as NMR.…”

ESR Spectroscopy of Multiphase Polymer Systems

“…However, in some inhomogeneous systems the programs have failed to reproduce experimentally observed spectra [6,30]. Particularly, the main problem in simulating ESR spectra occurred when reproducing the spectra of slow motion.…”

Anisotropy in Hybrid Materials: An Alternative Tool for Characterization

“…The mixture is kept under reflux for 48 hours and then THF is evaporated. The reaction was monitored by 13 Si] = 10-2) has been already described (6). In the case of PBu based materials, the problem is more tricky because of the demixing of (OEt) 3 SiuPBunwSi(OEt) 3 -water mixtures.…”

“…A moderate broadening of the two lines (less than 10 and 20 Hz respectively) is measured when the toluene is entrapped inside the PBu 2800 materials. This is related to the slight hindrance of molecular mobility of molecules dissolved in a polymer above its glass transition temperature Tg (13) and the inhomogeneities of the material. When the materials is stretched, the shape of Ihe spectrum is modified, and each peak tends to split into a quadrupolar doublet.…”