Structure of Dendrimer Brushes: Mean-Field Theory and MD Simulations
W Cui and CF Su and H Merlitz and CX Wu and JU Sommer, MACROMOLECULES, 47, 3645-3653 (2014).
We present a systematic approach to characterize the stretching scenarios for dendrimer brushes. We compare mean-field theory for second-generation dendrimer brushes in good solvent, taking into account finite extensibility of chains, with direct molecular dynamics simulations. We analyze the stretching scenario of the dendrimers and find very broad distributions of forces acting on the free branches of individual molecules. Our results question the accuracy of a recently introduced method to determine the stretching scenario in terms of a simple scaling analysis of the monomer concentrations. Instead, the resulting scaling exponents appear to respond to model-dependent implementations of the molecular elasticity an observation which may open paths toward an improved theoretical modeling of polymers in numerical procedures. As a function of grafting density, dendrimer brushes are scaling in a similar manner as linear chain brushes, but systematic deviations exist which increase with the functionality and the number of generations of the dendrimers.
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