Polymer, Vol.39, No.22, 5315-5319, 1998
Morphology of diacrylate copolymer networks formed in liquid crystalline media
The morphology of polymer networks in polymer-stabilized liquid crystals (PSLC) can be controlled by copolymerization of different monomers at isothermal conditions. Copolymerization of 4,4'-bis(acryloyloxy) biphenyl (BAB) and 4,4'-bis(6-(acryloyloxy)hexyloxy)biphenyl (BAB6-a monomer similar to BAB, but with a hexamethylene flexible spacer between the mesogen and the polymerizable acrylate moiety) produces a polymer network of intermediate flexibility, leading to a morphology intermediate between the bead-like morphology of BAB and the smooth fibrous morphology of BAB6. However, copolymerization of BAB6 and BABB6, a monomer with a longer mesogen, can produce a single morphology characteristic of BABB6 alone. Furthermore, at very high polymerization temperatures, when differences in monomer reactivity may be exaggerated, copolymerization yields neither uniform composition nor morphology. Instead, morphologies characteristic of each homopolymer coexist. These studies emphasize the significance of monomer structure and reactivity for the polymer network morphology formed in liquid crystal media.