Poly(aryl ether oxazole)s with Trifluoromethyl Side Groups

In this paper the synthesis and characterization of four series of poly(aryl ether oxazole)s is described. Four different monomers of the type 2,5-bis(4‘-fluorophenyl)oxazole were prepared. They differed in the number and position of trifluoromethyl substituents at the phenyl rings. From these monomers polymers were synthesized by nucleophilic displacement of the fluorine atoms with various bisphenols. The electron-withdrawing property of the oxazole ring in para -position of the 4-fluorophenyl rings activates the monomers for nucleophilic displacement reactions. Characterization by 1 H, 13 C, and 19 F NMR spectroscopy, IR spectroscopy, GPC, DSC, thermogravimetry, and elemental analysis allowed us to determine the effect of the oxazole rings on solubility, glass transition temperature, and decomposition temperature in comparison with other five-membered heteroaromatic rings in polymers known from the literature. The oxazole rings increase solubility, decrease glass transition temperatures, and have no negative effect on the thermal stability. Introduction of trifluoromethyl groups at the phenyl rings improves solubility but has no simple uniform effect on the glass transition temperature.