SYNTHESIS AND THERMAL-PROPERTIES OF POLYESTERS FROM CYCLOTRIPHOSPHAZENE

Polyesters containing cyclotriphosphazene units have been prepared by phase transfer catalyzed two-phase polycondensation and direct polycon densation. The polycondensation of the acid chloride of xyphenoxy-2,4, 6,6-tetraphenoxy)cyclotriphosphazene (trans-CPP) and bisphenol A (BA) in the presence of benzyltriethylammonium chloride (BTEAC) as phase tr ansfer reagent gave a polyester with a molecular weight of 22,000, whe reas only oligomer was obtained by the polycondensation of the cis-iso mer with BA. The result indicates that the trans-isomer is favorable t o effective growth of the polyester. The direct polycondensation using SOCl2/pyridine and TsCl/DMF, however, resulted in the formation of lo w molecular weight polyesters even though trans-CPP was used. In the c opolycondensation of BA with acid chlorides of trans-CPP and terephtha lic acid, copolymers with molecular weights of 24,000-13,000 were obta ined. The homopolyester prepared from trans-CPP and BA exhibited a sig nificantly low glass transition temperature of 65 degrees C, and the c opolymers had glass transition temperatures in the range 220-91 degree s C, depending on the contents of trans-CPP units. Thermogravimetric a nalysis showed that the homopolyester was stable up to 390 degrees C i n a nitrogen atmosphere, and the char yield of copolyester with 5.5 mo l.% of trans-CPP unit was 36% at 600 degrees C, which was seven times higher than that of the polyester without cyclotriphosphazene units. T he presence of cis-CPP units in the polyesters lowered the initial dec omposition temperatures, but not char yields. Copyright (C) 1996 Elsev ier Science Ltd