Dynamic Propagation Depth in Substrate-Supported Polymer Films: A Molecular Dynamics Simulation
Yun Zhou, Jin Zhang, Jianhua Huang
Abstract
The properties of substrate-supported polymer films are strongly related to the properties of the substrate. This work studies the dynamic propagation depth of the substrate effect in polymer films using molecular dynamics simulations. From the layer-resolved diffusion of polymer chains, the dynamic propagation depth of the substrate effect into nonadsorbed chains λ dyn is estimated to be about 2.3 R g ( R g is the radius of gyration of polymers in the bulk) and 3.5 R g for the weakly and strongly attractive substrates, respectively, much larger than the thickness of the adsorbed layer h ads ≈ 1.2 R g . The dynamics of adsorbed and nonadsorbed polymers located below λ dyn strongly depend on the substrate attraction strength. Our results reveal that the influence of substrate on the nonadsorbed polymer chains comes mainly from the tails of adsorbed chains and provides new insights into the molecular mechanism of the propagation of the substrate effect in polymer films.