DYNAMIC PROPERTIES OF HOMOPOLYMER LAYERS ADSORBED ON A SOLID-SURFACE

Dynamic properties of homopolymer layers adsorbed on a solid surface f rom a dilute solution are examined through dynamic Monte Carlo simulat ions over a range of surface/segment interaction energies and at diffe rent bulk concentrations. In particular, we studied the relationship b etween the detachment rate of adsorbed polymers and the first Rouse re laxation rate of adsorbed chains. The power-law dependence of the deta chment rate on the chain length which we have reported earlier [Phys. Rev. Lett. 74, 2503 (1995)] is seen to correspond to the power-law dep endence of the first Rouse relaxation rate of the adsorbed chains, whi ch is also the same as the power-law dependence of the first Rouse rel axation rate of the free chains (nonadsorbed chains). However, the det achment rate is usually much slower than the first Rouse relaxation ra te of adsorbed chains. Increasing the surface/segment interaction ener gy (e in units of k(B)T) increases the difference between the two. Mor e interestingly, when e-1.0 or higher, the detachment rate decreases s ignificantly as one lowers the bulk concentration, but the first Rouse relaxation rate does not decrease significantly. The results seem to suggest that the detachment rate may become effectively zero (i.e., de tachment time goes to infinite) as one continuously decreases the bulk concentration in the strong adsorption limit (e greater than or equal to 1.0). (C) 1996 American Institute of Physics.