Dissipative Particle Dynamics Studies of Surface Dynamics of Thin Polymer Films

Thin films of polymers show capillary wave fluctuations that can be measured experimentally by X-ray Photon Correlation Spectroscopy, and which reveal the dynamics at the surface.  These surface dynamics have been shown to be well-modeled by a hydrodynamic continuum theory (HCT) considering the film to act as a thin film of the bulk continuum fluid when the polymer is a linear chain.  However, experiments have also suggested that chain tethering and non-linear chain architecture can modify the surface dynamics to differ from those expected from the HCT.   We have performed Dissipative Particle Dynamics simulations to investigate the surface dynamics of thin films of both linear and ring polymers.  By time-correlating the surface fluctuation amplitudes, we compare the relaxation times to the HCT, and demonstrate the role of non-linear architecture on the surface relaxation.