Polymer Thermophoresis\nby Mesoscale Simulations

We employ mesoscopic simulations to study the thermophoretic\nmotion\nof polymers in a solvent via multiparticle collision dynamics (MPCD).\nAs the usual solvent–monomer collision rules employed in MPCD\ninvolving polymers fail to cause thermophoresis, we extend the technique\nby introducing explicit solvent–monomer interactions, while\nthe solvent molecules remain ideal with respect to one another. We\nfind that with purely repulsive polymer–solvent interaction,\nthe polymer exhibits thermophilic behavior, whereas to display thermophobic\nbehavior, the polymer–solvent potential requires the presence\nof attractions between solvent particles and monomers, in accordance\nwith previous experimental findings. In addition, we observe that\nthe thermophoretic mobility is independent of polymer length in the\nobserved regime, again in agreement with experiments. Finally, we\ninvestigate the thermophoretic behavior of block copolymers, demonstrating\nthat the thermophoretic mobility can be obtained by linear interpolation,\nweighted by the relative lengths of the two blocks.