Novel Phenylethynyl-Endcapped Polyimide Oligomers:Synthesis and Characterization

摘要

A series of novel phenyiethynyl-endcapped polyimide oligomers were prepared by polycondensation of an aromatic diamine mixture of 1,3-bis(4-aminophenoxy)benzene(1,3,4-APB)and 3,4-oxydianiline(3,4-ODA)with different aromatic dianhydrides including 3,3,4,4-biphenyltetracarboxylic dianhydride(BPDA),4,4'-(hexa-fluoro isopropylidene)diphthalic anhydride(6FDA),4,4-oxydiphthalic anhydride(ODPA),and 4,4'-[2,2,2-trifluoro-1-(3',5'-bis-(trifluoro-methyl)phenyl)ethylidene]-diphthalic anhydride(9FDA)in the presence of 4-phe-nyl-ethynylaniline(PEA)as endcapping agent in aprotic solvent at elevated temperature.The chemical structures,thermal behavior,and melt rheological properties of the synthesized polyimide oligomers were investigated.Experimental results indicated that the fluori-nated polyimide oligomers derived from 6FDA(PI-2)and 9FDA(PI-4)are amorphous solid resins and exhibited lower melt viscosities than those prepared from the unfluorinated aromatic dianhydrides such as BPDA and ODPA.The BPDA-based polyimide oligomers with a molar ratio of 1,3,4-APB/3,4'-ODA=50:50(PI-5)showed lower melt viscosity than those derived from a mixture of 1,3,4-APB and 3,4'-ODA with molar ratios of 75:25 and 100:0,respectively.In addition,the melt viscosity of the polyimide oligomers increased obviously with increasing of the polymer calculated molecular weights.