Synthesis and properties of novel organosoluble polyimides derived from 1,4-bis[4-(3,4-dicarboxylphenoxy)]triptycene dianhydride and various aromatic diamines

摘要

A novel triptycene-based dianhydride,1,4-bis[4-(3,4-dicarboxylphenoxy)]triptycene dianhydride,was prepared from 4-nitro-N-mefhylphfhal-imide and potassium phenolate of 1,4-dihydroxytriptycene (1).The aromatic nucleophilic substitution reaction between 4-nitro-N-methylphthal-imide and 1 afforded triptycene-based bis(N-methylphthalimide) (2),which hydrolyzed and subsequently dehydrated to give the corresponding dianhydride (3).A series of new polyimides containing triptycene moieties were prepared from the dianhydride monomer (3) and various diamines in m-cresol via conventional one-step polycondensation method.Most of the resulting polyimides were soluble in common organic solvents,such as chloroform,THF,DMAc and DMSO.The polyimides exhibited excellent thermal and fhermo-oxidative stabilities with the onset decomposition temperature and 10% weight loss temperature ranging from 448 to 486 °C and 526 to 565 °C in nitrogen atmosphere,respectively.The glass transition temperatures of the polyimides were in the range of 221-296 °C.The polyimide films were found to be transparent,flexible,and tough.The films had tensile strengths,elongations at break,and tensile moduli in the ranges 95-118 MPa,5.3-16.2%,and 1.03-1.38 GPa,respectively.Wide-angle X-ray diffraction measurements revealed that these polyimides were amorphous.