Preparation and thermal properties of dicyanovinyl end-capped reactive oligomers

Abstract

Six aromatic diamines were prepared by reacting p-nitrobenzoyl chloride with the corresponding aromatic diol and diamine or 4-nitrophthalic anhydride with 4,4′-oxydianiline, followed by catalytic hydrogenation. Various dicyanovinyl end-capped reactive oligomers containing arylate, aramide, imide, alkyl ether and alkyl amide units were prepared from the above diamines and 1-chloro-1-phenyl-2,2-dicyanoethene. All the dicyanovinyl end-capped reactive oligomers were characterized by spectroscopy and elemental analysis. They are soluble in N,N-dimethylformamide and N-methyl-2-pyrrolidinone, and partially soluble in tetrahydrofuran and acetone. When the curing behavior of the polymer precursors was examined by means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), they showed a large exotherm around 350°C attributable to the curing of the dicyanovinyl group. The reactive oligomers containing rigid aromatic arylate, aramide and imide linkage showed no weight loss at curing temperature. Thermogravimetric analyses exhibited thermal stability with a 10% weight loss around 450°C and 75–90% residual weight at 500°C under nitrogen.