Liquid Crystalline Phases of Polymer Brushes

The phase behavior of liquid-crystal polymeric brushes in solvent are investigated using self-consistent field theory. The polymers are modeled as freely-jointed chain consisting of $N$ rigid segments. The isotropic interactions between the polymer and the solvent are treated using the standard Flory-Huggins theory, while the anisotropic liquid-crystalline (LC) interactions between rigid segments are taken into account using the Mayer-Saupe theory. For weak LC interactions, the brush exhibits the conventional parabolic-like profile, while for strong LC interactions, the polymers crystallize into a dense brush with a step-like profile. At intermediate interaction strengths, we find the microphase-segregated phase observed previously for lattice-model calculations.\footnote{V. M. Amoskov, T. M. Birshtein, and V. A. Pryamitsyn, Macromolecules, {\bf 31}, 3720 (1998).} In this phase, the brush exhibits a crystalline layer next to the grafting surface with an external layer similar to the conventional brush.