Effect of meta-Carborane on Segmental Dynamics in a Bimodal Poly(dimethylsiloxane) Network

摘要: Bimodal networks of polydimethylsiloxane (PDMS) filled with varying amounts icosahedral meta-carborane (m-CB) have been developed and characterized by broadband dielectric spectroscopy (BDS) static 1H multiple quantum nuclear magnetic resonance (MQ NMR). Both BDS MQ NMR showed evidence for a decrease in the polymer chain dynamics. spectra quantified normal-mode relaxation near 40 Hz at °C. The frequency maximum observed samples decreased increasing m-CB content until contents greater than 5 wt %. width spectrum increased addition small quantities filler that Agglomeration effects were loadings % as manifest onset low Maxwell-Wagner-Sillars (MWS) processes. data allowed characterization distributions residual dipolar couplings, and, thus, dynamic order parameter, Sb, consistent bimodal network architecture expected from synthesis protocol used. Upon less 10 filler, mean longer chains 46% distribution 33%. shorter much less, indicative preferential dispersion particles long domains structure. We conclude mechanism reinforcement is likely free volume space filling transitioning to complex molecular interaction phenomena higher loadings.