Effect of Polymer-Polymer Interface on Polymer Chain Dynamics*

Polymer membrane based separation techniques offer promise as energy efficient alternatives to distillation. In practice, thin membranes of polymers of interest are supported on another polymeric substrate for mechanical stability. It is thus important to decipher the effects of the polymeric support on the chain dynamics of the supported polymer.
In previous work, we showed the potential of polyacrylate gels as candidate materials for separating dilute alcohol-water mixtures by the process of pervaporation. In this study, we have used molecular dynamics simulations to investigate the dynamics of thin layers of polyacrylate gels that are supported on a polysulfone layer. Specifically, homopolymers and random copolymers formed by n-butyl acrylate and 2-hydroxyethyl acrylate monomers are studied. The effect of each polymer layer on the chain dynamics of the neighboring layer is discussed in the context of the glass transition temperature and short time scale dynamics in these layered systems. The observed trends in the dynamics of the individual layers are compared with the results of our earlier study involving bead-spring models of layered polymer systems and are interpreted in terms of the flexibility differences between the layers and the interlayer interactions.