Epoxy-Based PDLCs: Formation, Morphological, and Electrooptical Properties

• Published in: Heterophase Network Polymers pp. 167 - 180
• Main Authors: Gur’eva, Lyudmila L., Nosov, Georgii B., Gerasimov, Vladimir K., Chalykh, Anatolii E., Sonin, Anatolii S., Rozenberg, Boris A.
• Format: Book Chapter
• Language: English
• Published: Routledge 2002
• Edition: 1
• Subjects: IR Spectrum; Drop Size; Free Induction Decay; Heterophase Network Polymers; Conversion Degree; Reaction Induced Phase Separation; Electrooptical Investigation; Electrooptical Response; Reactive Blend; Dense; Nitrile Group; Electrooptical Properties; Epoxy Groups; Nematic Temperature; Phase Separation; Isothermal Calorimetry; LC-609 Concentration; Polymeric Liquid Crystalline; Drop Size Distribution; Nematic Liquid Crystals; Field Strength; Pip; Diglycidyl Ether; Nematic Isotropic Phase Transition; PDLC Film
• ISBN: 0415284171; 9780415284172
• DOI: 10.1201/9780203005491-18

168Kinetics of polymerization and polycondensation of diglycidyl ether of bisphenol A under the action of tertiary and primary amines in the presence of nematic liquid crystals (LC) based on n-pentylcyanbiphenyl was studied by isothermal calorimetry and IR spectroscopy. The presence of LC was shown to decelerate these reactions. An explanation of this phenomenon is proposed. The temperature of LC-isotropic phase transition was measured as a function of the reaction conversion. The morphology of obtained polymer dispersed liquid crystals (PDLC) with different nematic concentrations and network densities of polymer matrix was studied by optical and scanning microscopy. Some electrooptical properties of PDLC films were investigated. Transmission and relaxation times depending on high frequency pulse voltage were measured. It was shown that decrease of network density of polymer matrix led to a decrease in transmission and threshold strength of the electric field, to an increase in the pulse relaxation time, and to distortion of the electrooptical response. The data obtained were explained by the difference between the refractive indices of nematics and polymer matrix and a decrease in the matrix rigidity.