A Perspective on the Dynamics Properties in Polymer Nanocomposites.

Polymer nanocomposites (PNCs) usually have superior properties than pristine polymers. Understanding the dynamics properties in PNC system is crucial to reveal the mechanism of property change unpon the addition of nanoparticles (NPs), and therefore for a better design of the material properties. In this short perspective, we summarize recent advances mainly from theoretical and simulation studies of dynamics properties in polymer nanocomposite system. One is the "vehicle model" which reveals that diffusion dynamics of sticky NP is coupled to surrounding chain segments. Similarly, recent simulations demonstrate that such coupling also exists in all-polymer nanocomposite wich is composed of linear polymer chains and single-chain nanoparticles (SCNPs). These SCNPs have almost the same chemical composition as the matrix chain. Therefore, it is assumed that such all-polymer nanocomposite can act as a model system where there are no enthalpic interactions between NPs and polymer chains. Although the above dynamic coupling was found in the above two different systems containing inorganic NPs or relatively small organic SCNPs, it was found that the length scale of such dynamic coupling (the thickness of the matrix/NP interface) is comparable to the NP size, which is surprisingly consistent in the above two different systems. In addition, a chain-length dependence of the NP influence on the chain dynamics reported from a recent joint simulaiton and experimental study of all-polymer nanocomposite system, and a theoretical model developed for such phenomena are also reviewed. At the end, we give an outlook of this field, especially for possible chain-length dependence of complex dynamics in sticky-NP systems. [ABSTRACT FROM AUTHOR]