Controlling Reinforcement in Polymer Nanocomposites by Changing Rigidity of Adsorbed Chains

The study of polymer interface in polymer nanocomposites (PNC) has seen considerable attention in the last decade. We investigate the interactions between polymer-adsorbed nanoparticles (NP) and the matrix polymer, and the effect of polymer rigidity on the mechanical properties. In this study, we compare three distinct high glass transition temperature (T_g) polymers, poly(carbonate), poly(methyl methacrylate), and poly(2-vinylpyridine), having different characteristic ratio (C_∞), adsorbed on silica NPs and dispersed in the same matrix polymer, poly(ethylene oxide). Our rheology results show that the mechanical response of the PNC decreases with increasing the rigidity of the adsorbed polymer. The storage modulus of the least rigid polymer was found to be 10 times higher than that of the most rigid one at low frequencies. This unusual rheological result is attributed to the adsorbed polymer chains’ conformation on the substrate and the degree of entanglement with the matrix polymer. Rigid polymer tends to have flattened chains on the substrate which limits the interaction with the matrix polymer.