Benjamin Carbonnier

Light Scattering from Monomeric and Electron Beam Cured Acrylate/E7 Systems

A static light scattering study of monomeric (uncured) and Electron Beam (EB) cured Tripropyleneglycoldiacrylate (TPGDA) and E7 (a nematic Liquid Crystal) systems is reported. This study includes a detailed investigation of the structural properties in terms of temperature, composition and scattering angle. Knowledge of the phase diagrams helps us to achieve a better understanding of the scattering curves and rationalize data in terms of the LC configuration inside droplets. The depolarized component of the scattered intensity measured under cross polarizers exhibits patterns reminiscent of anisotropic objects. The results can be correlated to the electro-optical responses of the investigated systems relevant to applications in display technology and smart windows.

Physical properties of electron beam-cured tripropyleneglycoldiacrylate and liquid crystal systems

Some salient features of physical properties of Tripropyleneglycol diacrylate (TPGDA) and the low molecular weight nematic liquid crystal E7 are discussed. A variety of experimental techniques giving complementary information of monomer and Electron Beam (EB) cured systems are employed to illustrate the effect of curing. A detailed thermophysical analysis is made first to assess the conditions of miscibility, determine the order-disorder transition and the glass transition temperature. DSC spectra yield the energy change at the transitions from which important parameters are readily extracted such as solubility limits and amount of liquid crystal dissolved in the polymer. Polarized Optical Microscopy enables us to follow phase transitions and morphology changes in different regions of the phase diagram. Consistent data are obtained from mechanical measurements in particular with regards to the variation of the glass transition temperature with liquid crystal concentration and the related plasticizing effect.

Static light scattering from Tripropyleneglycoldiacrylate/E7 mixtures: Theorie and experiments

Experimental static Small Angle Light Scattering(SALS)data obtained from a selected monomer–liquid crystal system are presented. A blend involving the eutectic nematic mixture of low molecular weight liquid crystals(E7)and a difunctional monomer(tripropyleneglycoldiacrylate or TPGDA)was choosen to highlight the variations of the light scattering intensity in terms of scattering and azimuthal angles. Measurements of SALS were made in the VH mode under cross-polarized optical alignments.The experimental results were compared to a theory developed originally for bulk semi-crystalline polymers showing an anisotropic behavior and adapted to liquid crystalline systems. Depolarized light scattering intensities were calculated for isolated spherical droplets of liquid crystal molecules exhibiting a radial configuration. In particular, the characteristic anisotropic features of radial droplets in the VH mode were obtained both experimentally and theoretically. A good agreement between theoretical results and experimental findings was found for droplet radii of 5 μm.