1B04 Molecular Alignment and Intermolecular Interaction at (Polymer/LC) Interface Evaluated by Interface Enhanced Sum-Frequency Generation Method

Abstract

Interface enhanced sum-frequency generation (ISFG) method is a second-order nonlinear optical technique, which is a powerful tool to study the surface and the interface. The ISFG method was used for investigating 4-cyano-4'-pentylbiphenyl (5CB) behavior at the (polymer/5CB) interface. Poly (vinyl cinnamate) and poly (vinyl alcohol) were used as polymer. In both ISFG spectra, the absorbance bands attributed to the CN-stretching bands of 5CB were observed. At the (PVCi/5CB) interface, the absorbance band of CN-stretching appeared at 2225 cm^<-1>, which was in good agreement with CN-stretching band in the FT-IR spectrum of 5CB in the bulk state. However, at the (PVA/5CB) interface, the band of CN-stretching was sifted 100 cm^<-1> to lower wavenumber. This results indicate that the intermolecular interaction between PVA and 5CB is much larger than the case of PVCi and 5CB.