Microphase coexistence in polymeric brushes

A collapse of polymeric brushes in a solvent can be induced by a change in external conditions, for example, solvent quality or its temperature. The systems with following specific interactions are considered in this paper, namely, polyelectrolyte brushes, amphiphilic brushes in a mixture of incompatible solvents, and brushes with possibility of liquid-crystalline ordering of polymer segments. For all the systems it is shown that the brush collapse can be observed under certain conditions, and it occurs through a microphase segregation. There are two microphases of different densities that coexist in the brush. The effect is caused by general properties of the swollen phase of polymeric brush and hence appears at all types of the interactions that can induce a phase transition of the brush into collapsed state.