Configurational behavior of adsorbed polymer molecules

Monte Carlo calculations of the configurational behavior of adsorbed polymer molecules are described. Freely rotating lattice chains of 30, 50, 75, and 100 bonds adsorbing from athermal solutions at different adsorption energies have been studied. The adsorption energy is defined as Δϵs, the energy change on breaking a segment–solvent bond and forming a segment–surface bond. Adsorption occurs only for negative values of Δϵs. Results of calculations at Δϵs = −0.9kT and −0.5kT have been analyzed numerically and compared with previous data. Several ways of characterizing the configurational behavior are presented in terms of fraction of segments adsorbed, thickness of adsorbed layer, “train,” “loop,” and “tail,” lengths, and (r2) and (s2) of the adsorbed chain. At Δϵs = −0.9kT the chains are strongly adsorbed with extended configurations and short tails. At Δϵs = −0.5kT the chains are only just adsorbing with the thickness of the adsorbed layer dominated by the lengths of the tails. Finally, a visuographic technique for presenting the ciné display of the configurational behavior of the adsorbate chains is described briefly.