SYNTHESIS AND CHARACTERIZATION OF NEW SOLUBLE POLYIMIDES DERIVED FROM-BIS[3,5-DIMETHYL-4-(4-AMINOPHENOXY)PHENYL]PROPANE

A diamine monomer containing isopropylidene and methyl substituted ary lene ether, 2,2- bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]propane (TB APP), was prepared in two steps. The monomer was reacted with six diff erent aromatic tetracarboxylic dianhydrides in N,N-dimethylacetamide ( DMAc) to obtain the corresponding new polyimides via the poly(amic aci d) precursors and thermal or chemical imidization. The poly(amic acid) s obtained had inherent viscosities ranging from 1.38-2.10 dL . g(-1). All the poly(amic acid)s could be cast from DMAc solutions and therma lly converted into transparent, flexible, and tough polyimide films. T he polyimide films had a tensile strength in the range from 52-95 MPa, an elongation at break within a range of 4-8%, and a tensile modulus in the range from 1.60-2.09 GPa. All polyimides were amorphous. The po lyimides derived from diamine TBAPP had excellent solubility in variou s solvents except for those derived from rigid dianhydrides such as py romellitic dianhydride and 3,3',4,4'- biphenyltetracarboxylic dianhydr ide. These polyimides showed glass transition temperatures between 249 -293 degrees C and decomposition temperature at 10% mass loss temperat ures ranging from 460-485 degrees C in nitrogen.