Synthesis and characterization of new thermally stable poly(ester-imide)s derived from 2,2′-bis(4-trimellitimidophenoxy)biphenyl and 2,2′-bis(4-trimellitimidophenoxy)-1,1′-binaphthyl and various aromatic dihydroxy compounds

A series of new alternating aromatic poly(ester-imide)s were prepared by the polycondensation of the preformed imide ring-containing diacids, 2,2'-bis(4-trimellitimidophenoxy)biphenyI (2a) and 2,2'bis-(4-trimellitimidophenoxy)-1,1'-binaphthyl (2b) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. A model compound (3) was also prepared by the reaction of 2b with phenol, its synthesis permitting an optimization of polymerization conditions. Poly(esterimides) were fully characterized by FTIR, UV-vis and NMR spectroscopy. Both biphenylene- and binaphthylene-based poly(ester-imide)s exhibited excellent solubility in common organic solvents such as tetrahydrofuran, m-cresol, pyridine and dichloromethane. However, binaphthylene-based poly(esterimide)s were more soluble than those of biphenylene-based polymers in highly polar organic solvents, including N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide and dimethyl sulfoxide. From differential scanning calorimetry thermograms, the polymers showed glass-transition temperatures between 261 and 315 degrees C. Thermal behaviour of the polymers obtained was characterized by thermogravimetric analysis, and the 10 % weight loss temperatures of the poly(ester-imide)s was in the range 449-491 degrees C in nitrogen. Furthermore, crystallinity of the polymers was estimated by means of wide-angle X-ray diffraction. The resultant poly(ester-imide)s exhibited nearly an amorphous nature, except poly(ester-imide)s derived from hydroquinone and 4,4'-dihydroxybiphenyl. In general, polymers containing binaphthyl units showed higher thermal stability but lower crystallinity than polymers containing biphenyl units. (c) 2005 Society of Chemical Industry