Simulation of adsorption of flexible chains: Concentration effects

The influence of adsorbate concentration on the configurational properties of a flexible 30-segment linear chain adsorbed at a plane surface has been investigated by non-lattice Brownian dynamics simulation. Numerical results are presented as a function of adsorption strength (0-8kT) and volume fraction (0-4 vol.%) for (i) the proportions and sizes of train, loop and tail segments, (ii) the surface coverage, (iii) the average segment density distribution and (iv) the train segment desorption rate. The simulations demonstrate the substantial extent of conversion of train segments into loop and tail segments, and the consequent increase in adsorbed layer thickness, owing to the competitive presence of additional potentially adsorbable segments at high adsorption strengths. The results are qualitatively consistent with previous predictions of lattice-based theory for homopolymer adsorption.