Starlike polymer brushes in Theta-solvent
CF Su and W Cui and H Merlitz and CX Wu and JU Sommer, POLYMER, 55, 3254-3260 (2014).
The properties of starlike polymer brushes in Theta-solvent are investigated using molecular dynamics simulations, scaling- and mean- field theory. Deviations of layer thickness and monomer density from predictions of scaling theory are analyzed and explained. Contrary to common believes, we conclude that the Alexander-deGennes scaling theory is not valid for starlike polymer brushes in Theta-solvent, unless the grafting density is extremely low. A comparison with structural and dynamical properties of starlike polymer brushes in good solvent is carried out. Previous studies in good solvent reported about the dual- population structure of these branched polymer brushes, with coexisting phases of stretched and retracted molecules; the same separation emerges in Theta-solvent, though at higher grafting densities. Molecular tension and population fractions are shown to be solvent-dependent, and a reduced dynamical flip-rate between the two populations is observed for the case of the Theta-brush. (C) 2014 Elsevier Ltd. All rights reserved.
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