Synthesis of polycarbonate based on di-(4-hydroxyphenyl)methylphenylmethane in organic solvents

Abstract

Polycarbonates (PC) are prepared mainly by phosgenization in pyridine medium, or on the interface of two immiscible solvents. One of the disadvantages of the latter method is that a large amount of low-molecular impurities (e.g. NaCl) are present; the latter are difficult to remove from the polycarbonate, and greatly impair both the thermal stability and the dielectric properties of the polymer. In the case of phosgenization in pyridine it is necessary to use large amounts of this solvent, and because of this difficulties are encountered in separating and purifying the PC. Papers recently published by a number of authors deal with the synthesis of polyesters novel method envisages the use of tertiary amines (catalyzing the polycondensation reaction) in amounts equal to or slightly less than the stoichiometric ratio of the reactants, and this method is free from the disadvantages inherent in the first two methods. However, only a very limited amount of information has been published in regard to the synthesis of PC by the method in question [3], and it is insufficient to give a clear idea of the chemism of the process. At the same time the reactions involved in the formation of PC by this method may be regarded as model reactions taking place homogeneously in organic solvents, and possibly occurring during the synthesis of PC on the interface. It should be noted that the high rate of the reaction and the presence of the interface make the problem of investigating the interfacial polycondensation process considerably more difficult.