2H NMR study of molecular motions in polydimethylsiloxane and its mixtures with aerosils

Abstract 2H NMR was used to investigate the effect of fillers on the molecular motions in mixtures of polydimethylsiloxane (PDMS) with different fillers. For active fillers with hydrophilic surface OH groups the molecular mobility at the polymer‐filler interface is strongly different from that outside the adsorption layer. The influence of concentration and type of filler on molecular motions was determined. In particular an adsorption layer differing in mobility from bulk PDMS could be detected just above the glass transition temperature in systems filled with hydrophobic Aerosil. The role of molecular dynamics at the polymer‐filler interface for the reinforcement of silicon rubbers is discussed.