Pecularities of the molecular weight distribution at the one‐ and two‐phase synthesis of linear polyquinoxalines by polycondensation in solution

Abstract The molecular weight distribution of a series of polyphenylquinoxalines obtained by polycondensation of 1,4‐(phenylglyoxalyl)benzene with 3,3′,4,4′‐tetra‐aminodiphenyleneoxide in one‐ and two‐phase systems was determined by fractionation, sedimentation and viscosimetry. The molecular weight distribution of the products of homogeneous polycondensation at 20°C is approximated by the most probable distribution. It became broader with increasing the temperature of reaction to 200°C. In the two‐phase polycondensation the molecular weight distribution was found to be narrower than the most probable distribution.