Molecular Tailoring of Fluorocarbon Ether Bibenzoxazole Polymers to Lower Glass Transition Temperatures

摘要

The synthesis of fluorocarbon ether bis(o-aminophenol) monomers was accomplished by a multistep route from long-chain fluorocarbon ether diiodides and the reaction conditions optimized. Polycyclocondensation of these monomers with novel, long-chain fluorocarbon ether diimidate esters led to linear fluorocarbon ether bibenzoxazole (FEB) polymers soluble in hexafluoroisopropanol and Freon 113. Polymer structures were verified by elemental and infrared analysis. Some of the Feb polymers were obtained in moderate to high molecular weights with inherent viscosities in the range of 0.4 to 0.5 dl/g. High fluorocarbon ether content gave the desired low glass transition temperatures without significant sacrifices in thermooxidative stabilities. Rubbery polymers with glass transition temperatures as low as -58C (-72F) were obtained. With respect to thermooxidative stability, onset of weight loss of the FEB polymers during thermogravimetric analysis in an air atmosphere occurred in the 350-400 C (660-750 F) range.