Driven Chain Macromolecule in a Heterogeneous Membrane-Like Medium

Monte Carlo simulations are performed to study the conformational relaxation of a large polymer chain driven into a heterogeneous (membranelike) substrate on a discrete lattice. Chains are created on trails of constrained self-avoiding walks (SAW) on the lattice. Kink–jump, crank–shaft, and reptation moves are used to move segments of chains. Short chains of length L_sc are driven by a field E₁ toward an impenetrable substrate to design a membrane medium with mobile chain segments. A long chain of length L_lc is then driven by a field E₂ into the membrane medium and is subsequently allowed to relax in a field E₃. Radius of gyration R_g and end-to-end distance R_e of the long chain are examined. The relaxation of the conformation of the long chain and its magnitude is found to depend on the initial (predeposition) conformation of the chain, i.e., on E₂. For a relatively relaxed initial conformation (at E₂ = 0.1), the longitudinal component of the radius of gyration (R_gz) is found to decay with the driving field E₃ with a power law, R_gz E₃ where 0.1 at low field (E₃ 0.1) and 1/3 at high field E₃ 0.1.