| Abstract
| - The phase behavior of blends of polymers and smectic-A liquid crystals (LCs) is investigatedusing Flory−Huggins and Maier−Saupe−McMillan theories. Various examples are considered to depictthe effects of the architecture and the size of the polymer together with the nature of anisotropic orderingforces on the phase diagram. The strength of these forces is characterized by a parameter α which isdirectly related to the temperature of the smectic−nematic transition. Three cases are considereddepending on the value of α, and the corresponding phase diagrams are constructed. Substantialdifferences are observed in these diagrams, and the reasons for these differences are discussed. Acomparative study is performed between mixtures of polymers and LCs, where the polymer is made oflinear and crosslinked chains. The LC consists either of molecules with nematic ordering only or ofmolecules presenting both nematic and smectic-A ordering. Blends where polymer matrices are cross-linked networks are also examined. Remarkable properties are found in the nature of the phase diagramsfor such mixtures. In general, it is observed that the ordering forces favor unmixing with a strongereffect for the higher smectic-A ordering. Spinodal curves are also reported for these mixtures. The effectsof fluctuations near the transition temperatures are briefly discussed.
|
