Phase diagrams of poly(dimethylsiloxane) and 5CB blends

The phase diagrams of poly(dimethylsiloxane) (PDMS) and 4-cyano-4'-n-pentyl -biphenyl (5CB) mixtures are studied for two systems of different molecular weights of the polymer. The experimental diagrams are established by polar ized optical microscopy (POM), and analyzed using a combination of the Flor y-Huggins theory of isotropic mixing and the Maier-Saupe theory of nematic order. The results are compared with those of polystyrene (PS) and 4-cyano- 4'-n-octyl-biphenyl (8CB) with analogous molecular weight of the polymer. T his investigation could be useful for the choice of systems in electro-opti cal devices. (C) 2001 John Wiley & Sons, Inc.