Bound Polymer Layer induced Mechanical Enhancement in Polymer Nanocomposites

  The superior properties of polymer nanocomposites (PNCs) is believed to originate from adsorbed polymers around nanoparticles, particularly from the interfacial layer exhibiting slower segmental dynamics than bulk polymers. Meanwhile, the bound polymer layer created by the entire adsorbed polymer has distinguished chain conformations compared to bulk polymers; however, received less attentions than the dynamically defined interface layer.

  In this study, we focus on the significant effect of the bound polymer layer on the enhancement of physical properties by preparing PNC melts with different distributions of unimodal and bimodal molecular weight (MW) polymers. The bimodal MWs PNCs melt exhibited much greater rheological properties than those of unimodal PNCs even though the interfacial layer thickness in both systems was similar. The bimodal PNC has a thicker bound layer than the unimodal, which allows it easily to interact with adjacent bound layers or bulk polymers. However, the bimodal MW PNC shows faster dynamics than unimodal due to the presence of short polymers. These results imply that the chain conformation of the adsorbed polymers, can be critical in determining the properties of PNC.