Journal of Applied Physics
Polymer dispersions were made by photoinduced polymerization of 4,4'-bisacryloyl-biphenyl in liquid crystal 4-4'-cyano pentyl biphenyl as nematic solvent. Samples were prepared with 0.5, 1, and 1.5 wt % monomer. The polymerization was done in the isotropic phase. The rotational viscosities of the two lower concentration samples increased only moderately after UV curing (3 mW/cm2, 25 min). The 1.5 wt % sample gave under the same condition a nematic with a fairly rigid anisotropic network that did not realign in magnetic field up to 20 kG. We estimate that the mesh size of the network was in the order of 1 mum, significantly smaller than the magnetic coherence length of the solvent that is in the order of 5 mum. The diamagnetic anisotropies of the aligned samples were not affected significantly by the polymer. We studied electro-optical properties on thin films. The films were strongly light scattering but they could be switched to transparent state. We conclude that the polymer forms a network of loosely connected fibrils that interacts strongly with the director field.
Jákli, Antal; Kim, D. R.; Chien, Liang-Chy; and Saupe, A. (1992). Effect of a Polymer Network on the Alignment and the Rotational Viscosity of a Nematic Liquid-Crystal. Journal of Applied Physics 72(7), 3161-3164. Retrieved from http://digitalcommons.kent.edu/cpippubs/64