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.
Journal of Applied Physics
Copyright 1992 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in J. Appl. Phys. 72, 3161 (1992) and may be found at http://dx.doi.org/10.1063/1.351478.
Jakli, Antal; Kim, D. R.; Chien, Liang-Chy; 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 https://oaks.kent.edu/cpippubs/64