Synthesis and characterization of highly soluble poly(aryl ether ketone-benzoxazole) copolymers with hexafluoroisopropylidene moieties by direct copolymerization

摘要

A series of new poly(aryl ether ketone-benzoxazole)s (PAEKBOs) with hexafluoroisopropylidene moieties were synthesized directly by the aromatic nucleophilic 1 polycondensation of 2,2'-bi[2-(4-fluorophenyl)benzoxazol- 6-yl]hexafluoropropane(6F-BO), 4,4'-difluorobenzophenone (DFBP) and 4,4'-(hexafluoroisopropylidene)diphenol (6F-OH) at various molar ratios. High molecular weight polymers with both benzoxazole and ether-ketone units were readily i obtained. The copolymers with >20 mol-% content of etherketone units were highly soluble in organic solvents such i as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide ' (DMAc), N,N-dimethylformamide (DMF), m-cresol, tetrahy drofuran (THF) and CHCl3. The thermal stability of PAEKBOs was not significantly compromised compared with the i relevant homopolymer compositions, hexafluoroisopropylidene containing poly(aryl ether ketone) (6F-PAEK) without benzoxazole units and hexafluoroisopropylidene containing poly(ether benzoxazole) (6F-PEBO) without ether-ketone units. A 5% weight loss of the copolymers occurred at above 440 degrees C in air and above 480 degrees C in N-2. Single glass transition temperatures (T(g)s) were observed and ranged from 182 to 228 T depending on the composition of the copolymers. The PAEKBO copolymers were essentially in the amorphous state, as determined using DSC, WAXD and DMA. For polymer films with a thickness of 30-80 mu m, moduli between 1700 and 2 100 MPa and strengths between 40 and 90 MPa were achieved. The PAEKBO copolymers behaved in many respects as engineering thermoplastics and could be processed from solution and the melt.