Synthesis and liquid crystalline behavior of phosphorus-containing aliphatic–aromatic copoly(ester-imide)s

A series of phosphorus-containing copoly(ester-imide)s was prepared by polycondensation reaction of 2-(6-oxido-6 H -dibenzoxaphosphorin-6-yl)-1,4-naphthalene diol, 1 , or of various mixtures of 1 and 1,12-dodecanediol, 3 , with an aromatic diacid chloride containing preformed imide rings, 2 , namely 4-chloroformyl- N -( p -chloroformylphenyl)-phthalimide. The polymers exhibited thermotropic liquid crystalline behavior, as was observed by means of polarized light microscopy, differential scanning calorimetry, and X-ray investigations. The copoly(ester-imide)s showed good thermal stability having the temperature of 5% weight loss above 365–408 °C and char yield at 700 °C in the range 8.8–48%.