Roughening, deroughening, and nonuniversal scaling of the interface width in electrophoretic deposition of polymer...

Growth and roughness of the interface of deposited polymer chains driven by a field onto an impenetrable adsorbing surface are studied by computer simulations in (2+1) dimensions. The evolution of the interface width W shows a crossover from short-time growth described by the exponent beta(1) to a long-time growth with exponent beta(2) (>beta(1)). The saturated width increases, i.e., the interface roughens, with the molecular weight L(c), but the roughness exponent alpha (from W(s) approximately Lalpha) becomes negative in contrast to models for particle deposition; alpha depends on the chain length-a nonuniversal scaling with the substrate length L. Roughening and deroughening occur as the field E and the temperature T compete such that W(s) approximately (A+BT)E(-1/2).