COMPUTER-SIMULATION OF POLYMER ADSORPTION AT INTERFACES USING THE PIVOT ALGORITHM

Monte Carlo simulations of self-avoiding polymers using the pivot algorithm have been employed to determine monomer distribution profiles, surface excess, and conformational variables for homopolymers and copolymers at solid-liquid and liquid-liquid interfaces in the dilute limit. A modified version of the pivot algorithm is used which allows the equilibrium between bulk and adsorbed polymers to be simulated. The segmental distribution profile and surface excess are determined as a function of chi, the energy increase associated with a monomer in an unfavorable environment. For the model employed, a diblock copolymer adsorbs more readily than an alternating copolymer at a liquid-liquid interface, while an alternating copolymer adsorbs more readily than a diblock at a solid-liquid interface. Simulations have also been carried out for homopolymers grafted to a surface at one end and by assigning energetic parameters to segment-segment (phi = -epsilon(segment)/kT) and segment-surface (lambda = -epsilon(surface)/kT) interactions. The effect of these parameters on the shape of the polymers and the number of segment-segment and segment-surface contacts was studied.