Entangled dynamics of healing end-grafted chains at a solid/polymer interface

Abstract

We present theoretical calculations of the dynamics of end-grafted chains on a solid substrate approaching their equilibrium conformations within a compatible network placed on the substrate. We assume that TT_g and that the motion is dominated by entanglements. The problem has two limits corresponding to high and low surface-grafting density of the chains. In the latter case some chemical affinity between network and chain is required to ensure penetration. We make detailed calculations on each limit and find that in both cases there are three dynamical regimes: (i) fast Rouse-like penetration of part of the grafted chain, (ii) retraction of the free ends and (iii) diffusive dynamics of a slow variable. Both adhesive strength and interfacial width are predicted to grow on long timescales varying exponentially with molecular weight.