Development of Mesomorphic Poly(methyl methacrylate)

Methacrylate monomers were synthesized in four steps based on methacrylic acid and substituted phenols in the present investigation. In the first step, 4-(ω- hydroxy alkoxy) benzoic acids with ω = 2 and 6 were synthesized with the reaction of 4-hydroxy benzoic acid (PHB) and ω-chloroalkanol. The products were refluxed with methacrylic acid for 20 h to obtain the products of the type 4-(ω-methacryloyloxy alkoxy) benzoic acid. The products were chlorinated with thionyl chloride to obtain 4-(ω- methacryloyloxy alkoxy) benzoyl chloride. Finally, the chlorinated products were reacted with 4-methoxy and 4-hexyloxy phenols in dry benzene with triethylamine as catalyst at 0-5°C in nitrogen atmosphere for 3 h to obtain the methacrylate monomers. These monomers have been polymerized by free-radical polymerization technique at 50-60°C. The viscosity-average molecular weight (MV) of the synthesized polymers was calculated by Mark-Houwink''s equation with K and α values 3.87 * 10-3 dL/g and 0.42, respectively. Finally, the phase transitions and the transition enthalpies of polymers from the dynamic scans by differential scanning calorimetric analysis (DSC) gave an inference about the presence of nematic-isotropic and smectic-isotropic transitions in polymers. These liquid crystalline orders were further confirmed by X-ray diffraction analysis.