What really enhances the adsorption of polymers onto chemically nonuniform surfaces:Surface randomness or its heterogeneity?

摘要

We theoretically perform a comparative analysis of the adsorption of polymers onto the regularly and randomly nonuniform surfaces.By developing and making use of the self-consistent perturbation expansion we calculate the surface excesses of the polymers adsorbed on the random and periodically patterned surfaces.In both cases the enhancement of the polymer adsorption is indicated,as compared to the adsorption onto the homogeneous surface that has the same average affinity for polymers.Moreover,the results obtained for the randomly nonuniform and periodically patterned adsorbing surfaces show striking quantitative similarity,when compared at the same characteristic sizes of inhomogeneities of these surfaces.This finding leads to the conclusion that the adsorption ability of the nonuniform surface primarily depends on the characteristic size of the surface inhomogeneity,rather than on the spatial distribution of the inhomogeneities on this surface.In all cases,the calculated total surface excess is found to be a decaying function of the ratio of the radius of gyration of polymers to the characteristic size of the surface inhomogeneity.The effect of the excluded volume is found to reduce the polymer adsorption.