On the miscibility of crosslinked networks and solvents with and without nematic order

The phase behavior of crosslinked polymer networks and solvents with and wi thout nematic order is investigated. The Flory-Huggins interaction paramete r chi is assumed to be function of temperature and polymer volume fraction. Effects of these variations on the miscibility of networks and low molecul ar weight solvents are discussed. Under certain conditions, equilibrium bet ween collapsed and swollen networks is observed. This behavior was not obse rved in previous studies where chi was assumed independent of polymer volum e fraction. If the low molecular weight component is a liquid crystal (LC), below the nematic-isotropic transition temperature nematic order induces a drastic loss of miscibility in the dilute polymer range. If the nematogens are attached to the polymer network as side chain LC groups, the loss of m iscibility is even larger but localized in the dense polymer region. The ph ase diagram in the whole range of composition is discussed.