Effects of polymer architecture on the phase properties of polymethylsiloxane/liquid crystal blends

The phase properties of polydimethylsiloxane (PDMS) and low molecular weigh t liquid crystals (LMWLCs) with different size and architecture of the poly mer are investigated. An oligomer of molecular weight 800 g/mol and two lin ear polymers of molecular weight 5500 and 45000 g/mol are considered. Elect ron beam cured PDMS/4-cyano-4'-n-pentyl-biphenyl (5CB) mixtures in which th e polymer is a crosslinked network are also investigated. Experimental phas e diagrams are established using polarized optical microscopy (POM) and ana lyzed using classical theories for the free energy of isotropic mixing, net work elasticity and nematic order.