THEORY OF GRAFTED POLYMER MONOLAYERS - CH AIN MODELS WITH FINITE EXTENSIBILITY

The theory of polymer monolayers densely grafted to a flat surface was developed within the framework of the mean-field approximation. An ar bitrary mechanism for extensibility of the grafted chains was assumed. It It was found that, for the layer of monodisperse polymer chains, t he self-consistent pseudopotential is controlled only by the mechanism providing chain extensibility and is independent of specific features of interchain interaction; that is, when interchain interaction varie s, the structure of monolayer changes so as to provide invariability o f the self-consistent pseudopotential. A general scheme for calculatio n of the self-consistent pseudopotential was elaborated. Analytical ex pressions for the self-consistent pseudopotential were derived for mod els of monolayers composed of freely jointed chains on square, diamond , and body-centered cubic lattices. Expansions of self-consistent pseu dopotential into series were derived for freely jointed chains on simp le cubic and face-centered cubic lattices, a continuum model of freely jointed chains, and lattice models with a banned backward step. The d ependences for self-consistent pseudopotential were used to calculate the structures of polyelectrolyte monolayers and of very densely graft ed monolayers immersed in a good solvent. The results of the theory sh ow quantitative agreement with previously reported data on numerical c alculations of the structure and properties of polymer monolayers.