Thermodynamics and kinetics of grafting end-functionalized polymers to an interface

Abstract

We present a theoretical study of the thermodynamics and of the kinetics of grafting end-functionalized polymers to an interface. The equilibrium surface coverage and thickness of the grafted layer are predicted as a function of molecular parameters such as the molecular weight of the chains, the solution concentration and the energy gained by adsorbing the terminal group. We show that there are two successive regimes in the kinetics of adsorption. The first one (short time) is governed by the Brownian diffusion of the chains in the solution, the second regime (long time) by the activation barrier, which appears as soon as the adsorbed chains begin to overlap strongly and to stretch. The characteristic construction time depends exponentially on the chemical affinity of the end group and on the surface. The desorption time of a brush put in contact with the pure solvent is also calculated. The desorption time is always longer than the construction time.