Dynamic Analysis of Polymer-Dispersed Liquid Crystal by Infrared Spectroscopy

Abstract

The dynamic behavior of a polymer-dispersed liquid crystal (PDLC) under an electric field has been studied by static and two-dimensional infrared spectroscopy. The PDLC sample was prepared by polymerization-induced phase separation of a mixture of nematic liquid crystal E7 and acrylate. 2D IR correlation analysis indicates that the rigid core of the liquid crystal molecules reorients as a unit, and suggests that the polymer side chain existing in the interface between the polymer and the liquid crystals may reorient in phase with the liquid crystal reorientation by interaction with the liquid crystal molecules.

Probing the Mesoscopic Chemical and Physical Properties of Polymer-Dispersed Liquid Crystals

“…Chemically selective methods, however, already exist and have been used extensively for such studies. The methods of choice include Raman scattering, [141] IR absorption spectroscopy, [70,125,126,140,153,159] and NMR spectroscopy. [86,143±145,147,148] In a recent paper, Kohri and co-workers reported the results of FTIR studies of liquid crystal reorientation dynamics in PDLC films.…”

FOURIER TRANSFORM INFRARED VIBRATIONAL SPECTROSCOPIC IMAGING: Integrating Microscopy and Molecular Recognition

“…Upon application of an electrical potential, all LC directors experience a rotational torque reorienting the molecule along the electric field; hence, for light incident along the direction of the applied field, the refractive index of the liquid crystal matches the ordinary refractive index of the polymer, resulting in a transparent composite. TR-FTIR techniques applied to PDLC switching studies (71)(72)(73) are particularly attractive as they allow a correlation of electro-optical properties with specific molecular motions. In employing conventional vibrational spectroscopic techniques to study molecular dynamics, the chemical selectivity is usually high, but the spatial specificity tends to be low or nonexistent.…”

“…In employing conventional vibrational spectroscopic techniques to study molecular dynamics, the chemical selectivity is usually high, but the spatial specificity tends to be low or nonexistent. Thus, studies of PDLCs using TR-FTIR spectroscopic techniques have either examined the average behavior of the composite (71,73) or have consisted of describing a few discrete points across the entire field of view of the composite (72). The latter study, for example, obtained the response sequential responses of the droplet bulk region and the matrix using a procedure involving a point-mapping spectrometer equipped with a microscope and apertures.…”

Structural consideration of the additive effects on the electro-optical properties of commercial nematic liquid crystal materials

“…The chemical structure and composition are well known and described in several papers [12,13] (Figure 1). Several perfluorinated additives, possessing functional groups were selected for their weak anchoring properties, and tested with E7 in our previous paper [14].…”