Synthesis and properties of soluble alternating copoly(amide-imide)s based on 1,2-bis(4-trimellitimidophenoxy)-4-t-butylbenzene and various aromatic diamines

摘要

A new diimide dicarboxylic acid,1,2-bis(4-trimellitimidophenoxy)-4-t-butylbenxene (I),was prepared by the condensation of 1,2-bis(4-aminophenoxy)-4-t-butylbenzene(1,2-BPA-tBB)and trimellitic anhydride(TMA) at 1:2 molar ratio.The diamine 1,2-BAP-tBB was first synthesized from 4-t-butylcatechol and p-chloronitrobenzene in the presence of potassium carbonate(K_2CO_3) adn then reduced by H_2NNH_2 an Pd/C.A series of novel poly(amide-imide)s (PAIs)III_a-III_k with inherent viscosities of 0.83-1.73dl/g was prepared from the diimidediacid I with various aromatic diamines(II_a-II_k) by direct polycondensation in a medium consisting of N-methyl-2-pyrroilidone(NMP) (as a solvent),triphenyl phosphite/pyridine (as condensing agents),and calcium chloride.Most of the polymers show excellent solubility in amide-type solvents such as NMP and N,N-dimethylacetamide (DMAc) and formed a tough,transparent,and flexible film by casting from DMAc solution.The film s have tensile strengths of 87-108MPa,elongations at break of 8-17precent,and initial moduli of 2.1-2.6GPa.The glass transition temperature of these polymers is in the range of 234-276degC and the 10precent weight loss temperature is above 475degC in air or in nitrogen.