The liquid-crystalline monomer n-(p-methacryloyloxy-benzylidene)-p-aminobenzoic acid: its synthesis, characterization and polymerization

✍ Scribed by Henk J. Haitiema; Gert O.R. Alberda van Ekenstein; Y. Yong Tan

• Book ID: 103073719
• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 771 KB
• Volume: 28
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(92)90206-h

✦ Synopsis

The monomer N-(p-methacryloyloxy-benzylidene)-p-aminobenzoic acid (MOBAB) has been extensively investigated. Several crystallization methods were developed in order to obtain it in a pure state. MOBAB showed a complicated thermal behaviour depending on the purification procedure, drying and ageing. Crystallization from p-dioxane or mixtures with THF led to monoclinic needle-like crystals that contained one molecule of dioxane to two molecules of MOBAB, as confirmed from X-ray examination. From combined DSC, WAXS and microscopic results, the various thermal transitions in °C (excluding those arising from solvents) could be assigned to

The interconversion between the K~ and K 2 crystal forms may be caused by the existence of two conformers of the aromatic azomethine moiety, as supported by a conformational analysis and literature data. Radical polymerization of MOBAB in DMF showed classical features and led to low molar mass polymers with T s of about 130°C. The polymers showed some ordering, possibly arrising from frozen-in nematic structures. Solutions in DMF showed a polyelectrolyte effect.