Document Type
Article
Publication Date
1996
Abstract
Kerr measurements, ellipsometry, and quasielastic light scattering have been used to probe nematic fluctuations and nematic wetting at an isotropic liquid crystal-substrate interface in four generations of liquid crystalline monodendrons and dendrimers. We find that the pretransitional behavior is qualitatively similar to that of low molecular weight liquid crystals, exhibiting a Landau-like divergence of the relaxation time and a logarithmic divergence of the optical retardation on approaching the nematic-isotropic phase transition from above. Quantitatively, we find that the transition temperatures of the monodendrons are typically about 0.5 K above the supercooling limit of the isotropic phase and that the orientational viscosities may be fit to a power law in molecular weight Mn, where the exponent ≤ 1.0.
Keywords
ellipsometry, interfaces (materials), light scattering, molecular weight, neutron scattering, optical Kerr effect, phase transitions, substrates, viscosity of liquids, x ray analysis, dendrimeric liquid crystals, Landau divergence, nematic liquid crystals
Publication Title
Macromolecules
Rights
Reprinted (adapted) with permission from Macromolecules 29:24, 7813-7819. Copyright 1996 American Chemical Society.
Recommended Citation
Jian-feng Li, Karl A. Crandall, Peihwei Chu, Virgil Percec, Rolfe G. Petschek, and Charles Rosenblatt. Dendrimeric Liquid Crystals: Isotropic−Nematic Pretransitional Behavior. Macromolecules 1996 29 (24), 7813-7819. DOI: 10.1021/ma961116b