Dendron Brushes in Polymer Medium: Interpenetration and Depletion

Structural properties of polymer brushes formed by branched tree-like macromolecules (dendrons) attached to a surface and immersed into a melt of linear polymer chains are studied by means of self-consistent field theory. The conformational swelling-to-collapse transition provoked in the brush by an increase in the degree of polymerization of mobile polymer chains is analyzed. It is demonstrated that the sharpness of this transition decreases upon branching of tethered polymers. The effect of architecture of the brush-forming macromolecules on penetration and exclusion of mobile polymers is considered. The regimes of full, partial, and peripheral penetration of mobile chains into the brush are distinguished. The depth of penetration of mobile polymers into the brush is calculated as a function of molecular masses of mobile chains and tethered dendrons, grafting density, and topological parameters of the brush-forming macromolecules. It is demonstrated that the penetration length decreases upon branching of tethered macromolecules. For sufficiently long mobile chains, the penetration length is controlled by the number of monomer units in the longest elastic path of the dendrons. The predictions of the analytical self-consistent field theory are in excellent agreement with the results of numerical modeling based on the Scheutjens–Fleer approach.