Thermal study of photopolymerization reaction in polyacrylate/liquid crystal blends

• Published in: Materials today : proceedings Vol. 31; no. Supplement 1; pp. S9 - S11
• Main Authors: Hadjou Belaid, Z., Benhabib, L., Beroguiaa, D., Abdoune, F.Z., Méchernène, L., Maschke, U.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 2020; Elsevier
• Series: Materials Today: Proceedings
• Subjects: Chemical Sciences; Liquid crystal; Material chemistry; Monomers; Phase separation; Polymerization/crosslinking; Polymers; Ultraviolet irradiation; Liquid crystal; Ultraviolet irradiation; Polymerization/crosslinking; Phase separation; Monomers; Monomers Liquid crystal
• ISSN: 2214-7853; 2214-7853
• DOI: 10.1016/j.matpr.2020.05.026

PDLCs composite materials (Polymer Dispersed Liquid Crystal) were elaborated by polymerization induced phase separation under UV-light. Binary systems composed of Tripropyleneglycol diacrylate (TPGDA) monomer and a liquid crystal mixture (E7) were used as starting materials in the process of polymerization/crosslinking leading to a phase separation between polymer and liquid crystal. The time behaviour of the optical transmission of these films was experimentally studied during the period of exposure to UV-light in the absence of external applied fields. The transmission versus time curves of in-situ UV-cured TPGDA/E7 films reveal three regions: A first domain corresponding to a transparent film of the initial TPGDA/E7 mixture before exposure to UV light, a second time domain where the sample exhibits a fast relaxation process just after the beginning of the UV irradiation of the monomer/LC blend and a unusual third domain, characterised by an enhancement of the film transparency at longer relaxation times. This process depends on the conditions of sample preparation and film thickness. In this study, a temperature of a sample has been controlled after, during and before the application of UV light.