DYNAMIC PROPERTIES OF HOMOPOLYMER LAYERS ADSORBED ON A SOLID SURFACE

摘要

Dynamic properties of homopolymer layers adsorbed on a solid surface from a dilute solution are examined through dynamic Monte Carlo simulations over a range of surface/segment interaction energies and at different bulk concentrations. In particular, we studied the relationship between the detachment rate of adsorbed polymers and the first Rouse relaxation rate of adsorbed chains. The power-law dependence of the detachment rate on the chain length which we have reported earlier [Phys. Rev. Lett. 74, 2503 (1995)] is seen to correspond to the power-law dependence of the first Rouse relaxation rate of the adsorbed chains, which is also the same as the power-law dependence of the first Rouse relaxation rate of the free chains (nonadsorbed chains). However, the detachment rate is usually much slower than the first Rouse relaxation rate of adsorbed chains. Increasing the surface/segment interaction energy (e in units of k(B)T) increases the difference between the two. More interestingly, when e-1.0 or higher, the detachment rate decreases significantly 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., detachment 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. [References: 54]