Abstract
Summary: A series of new poly(aryl ether ketone‐benzoxazole)s (PAEKBOs) with hexafluoroisopropylidene moieties were synthesized directly by the aromatic nucleophilic 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 obtained. The copolymers with >20 mol‐% content of ether‐ketone units were highly soluble in organic solvents such as N‐methyl‐2‐pyrrolidone (NMP), N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide (DMF), m‐cresol, tetrahydrofuran (THF) and CHCl~3~. The thermal stability of PAEKBOs was not significantly compromised compared with the 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 °C in air and above 480 °C in N~2~. Single glass transition temperatures (T~g~s) were observed and ranged from 182 to 228 °C 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 µm, moduli between 1 700 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.
Structure of PAEKBO.
magnified imageStructure of PAEKBO.