Dynamically asymmetric polymer blends on nanoparticles: Effects on chain conformation, entanglement and particle mobility in nanocomposites

We study polymer nanocomposites with particles adsorbing a high glass-transition temperature (Tg) polymer, uniformly dispersed in a low-Tg miscible matrix, forming a dynamically asymmetric interphase. The collected results clarify the effect of the interfacial polymer on the conformation and entanglement of the matrix chains, as well as on the slow nanoparticle mobility. We found no significant effect of softness of the bound chains on the matrix chain conformation at particle concentrations up to 31 vol percent. A dilation of the reptation tube was observed when the interfacial polymer is glassy; such effect disappearing above Tg. Remarkably, the mobility of the nanoparticles is strongly influenced by the dynamical asymmetry in the interphase, resulting in a diffusive or sub-diffusive particle motion depending on the length-scale experimentally probed.