LAUSR

Using molecular dynamics simulations, we study the response of a polymer brush exposed to co-nonsolvent (CNS), which acts as a preferential solvent for the polymer. We investigate a broad range of attractions between CNS and monomers and of grafting densities over the full range of cosolvent volume fractions. We compare our simulation results with the recently proposed adsorption–attraction model for co-nonsolvency in polymer brushes. The brush layer collapses with increasing CNS concentration into a more compact layer and followed by a reswelling toward sufficiently high CNS concentrations. As the strength of attraction of CNS toward the brush increases, the collapse transition becomes discontinuous. Increasing the grafting density leads to higher sensitivity with respect to CNS but also to a weaker collapse behavior as predicted from the analytical model. In the narrow collapse region, two states of the brush layer coexist, as can be expected from the type-II phase-transition behavior. The coexistence s...