Heat‐resistant thermosetting polymers based on a novel tetrakisaminophenoxycyclotriphosphazene

Abstract

AbstractTwo heat‐resistant thermosetting polymers (IX and X) have been developed based on a new cyclotriphosphazene containing tetrakisamine. These polymers were synthesized by the reaction of tetrakisamine (IV) with maleic anhydride followed by in situ cyclodehydration and polymerization of the maleimides (VII and VIII) at 235–240°C for 1.5 h and 290°C for 0.5 h. The thermogravimetric analyses (TGA) of the developed cyclotriphosphazene containing cyclomatrix polymers showed their thermal stability up to 350°C and char yield of 71% in nitrogen at 800°C and 65% in air at 700°C. The monomer, 2,2,4,4‐tetrakis(4′‐aminophenoxy) ‐6,6‐diphenylcyclotriphosphazene (IV), useful for producing a variety of heat‐ and fire‐resistant polymers, has been synthesized in good yield. Its syntheses involve Friedel‐Crafts reaction of hexachlorocyclotriphosphazene (I) with benzene followed by the reaction of 2,2,4,4‐tetrachloro‐6,6‐diphenylcyclotriphosphazene (II) with potassium 4‐nitrophenoxide. The reduction of the obtained 2,2,4,4‐tetrakis(4′‐nitrophenoxy)‐6,6‐diphenylcyclotriphosphazene (III) with molecular hydrogen in presence of PtO2 gave the tetrakisamine (IV). The structure of the synthesized monomer and intermediates were characterized by FT‐IR, 1H‐NMR, 31P‐NMR, mass spectroscopy, differential scanning calorimetry (DSC), and elemental analysis. These resins are potential candidates for the development of heat‐ and fire‐resistant composites, laminates, and adhesives, useful for space, aerospace, and electronic application. © 1993 John Wiley & Sons, Inc.