Theoretical phase behavior of crosslinked polymers and liquid crystals

Equilibrium phase properties of mixtures of crosslinked polymers and nematic liquid crystals (LCs) are investigated. Effects of the volume fraction of polymer at crosslinking phi (0), the number of monomers between consecutive crosslinks N-c and the Flory-Huggins interaction parameter chi on these properties are discussed. Two models for the elastic free energy are used to describe the effects of too Three cases are considered depending upon polymer volume fraction at crosslinking. If crosslinking takes place in the bulk, the elastic free energy is the same and the two models are identical. Otherwise, either phi (0) is constant or equal to phi (2), the two models may lead to completely different results depending upon crosslinking density. Strong correlations are found between the effects of phi (0) and N-c on the phase behavior of crosslinked polymers and nematic liquid crystal mixtures. These diagrams are also strongly dependent upon the Flory-Huggins interaction parameter for isotropic mixing chi. This dependence is illustrated through three models for the variation of chi with temperature and composition.