In condensed polymeric liquids confined in slit channels, the movement of chains is constrained bytwo factors: entanglement among the chains and the excluded volume between the chains and thewall. In this study, we propose a wall boundary (WB) model for the primitive chain network (PCN)model, which describes the dynamics of polymer chains in bulk based on coarse graining upon thecharacteristic molecular weight of the entanglement. The proposed WB model is based on theassumptions that (i) polymers are not stuck but simply reflected randomly by the wall, and (ii)subchains below the entanglement length scale behave like those in bulk even near the wall. Usingthe WB model, we simulate the dynamics of entangled polymer chains confined in slit channels. Theresults show that as the slit narrows, the chains are compressed in the direction normal to the wall,while they are expanded in the parallel direction. In addition, the relaxation time of the end-to-endvector increases, and the diffusivity of the center of mass decreases. The compression in the normaldirection is a natural effect of confinement, while the expansion is introduced by a hooking processnear the wall. The trends revealed that the relaxation time and diffusivity depend on the increase infriction due to an increased number of entanglements near the wall, which is also associated with thehooking process in the PCN model. These results are expected within the assumptions of the PCNmodel. Thus, the proposed WB model can successfully reproduce the effects of wall confinement onchains.
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