Backfolding Transitions in a Liquid Crystalline Polymer Brush

Liquid crystalline (LC) polymer brushes offer a convenient way of modifying surface properties for LC materials in, for example, LC displays. With this motivation in mind, we begin by studying LC polymer brushes in a simple solvent using self-consistent field theory. The polymers are modeled as worm-like chains with Maier-Saupe interactions. For good solvent conditions, the isotropic interactions favor a stretched brush while the anisotropic LC interactions favor folding into a high-density nematically collapsed brush. The brush undergoes first-order transitions as the number of folds increases. The folding transitions can be qualitatively understood through a simple analytic model balancing the energetic benefit from increased LC alignment and the cost associated with the bending energy of hairpin folds.