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Using Mw dependence of surface dynamics of glassy polymers to probe the length scale of free surface mobility (1909.01835v3)
Published 4 Sep 2019 in cond-mat.soft and cond-mat.dis-nn
Abstract: We describe a series of surface levelling experiments in glassy polystyrene (PS) of varying molecular weight. The evolution through a mobile surface layer is described by the glassy thin film equation that was introduced and used in a previous work. Excellent agreement with the data is achieved, with surface mobility as the single free parameter. Different molecular-weight dependencies in mobility are then observed above and below the glass transition. The results are discussed in terms of surface-chain anchoring in the bulk matrix, and the length scale for surface mobility.