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.

Included in

Physics Commons

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