SOLID STATE NMR CHARACTERIZATION OF POLYMERS AND SURFACTANT MOLECULES AS CONFINED TO POROUS SILICA MATERIALS

摘要

The present chapter is aimed at presenting the characterization of nanocomposites formed by mesoporous silica and surfactants or polymers. The hybrid materials were prepared in the former case by condensation of silica about micellar aggregations of surfactants; in the latter case novel polymer nanocomposites were formed by direct polymerization or by absorption of polymers in the pores of the mesostructured silica. The materials provide intimate interactions between the nanophases, and thus a challenging field for NMR characterization of the extended interfaces. The steric limits imposed to the chains by the rigid siliceous structure permit the controlled reduction of the degrees of conformational and translational freedom as compared to the bulk phases. Concerning polymers, unusual states of aggregation can be observed massively in these nanocomposites and basic phenomena, like glass transition or crystallization, are to be re-explored in the confined state. Preliminary NMR characterization of nanophase properties like confined crystallization of alkyl chains, or monomer reactivity in the inclusion state are described hereafter.