Abstract: The invention relates to a method for preparing polybenzimidazoles of formula (1) or (2) below, wherein n is ?2: by polycondensation of corresponding dicarboxylic acids or dialdehydes and tetraamines by jointly heating the reactants, characterized in that the preparation of polybenzimidazoles of formula (1) or (2) is carried out by using the dialdehydes as starting material and substantially without the formation of any intermediates, wherein a) first, the dialdehyde and the tetraamine are mixed in water at room temperature, which results in the formation of a polyimine by-product; whereafter b) polycondensation is carried out under hydrothermal conditions by heating, in water as a solvent and under pressure, to temperatures above 100° C.

Abstract: The invention relates to a method for preparing polybenzimidazoles of formula (1) or (2) below, wherein n is 2: by polycondensation of corresponding dicarboxylic acids or dialdehydes and tetraamines by jointly heating the reactants, characterized in that the preparation of polybenzimidazoles of formula (1) or (2) is carried out by using the dialdehydes as starting material and substantially without the formation of any by-products intermediates, wherein a) first, the dialdehyde and the tetraamine are mixed in water at room temperature, which results in the formation of a polyimine by-product; whereafter b) polycondensation is carried out under hydrothermal conditions by heating, in water as a solvent and under pressure, to temperatures above 100° C.

Abstract: The invention relates to a method for preparing polybenzimidazoles of formula (1) or (2) below, wherein n and m are each 1: by polycondensation of corresponding tetracarboxylic acids or dianhydrides and tetraamines by jointly heating the reactants, characterized in that the preparation of polybenzimidazoles of formula (1) or (2) is carried out by using tetracarboxylic acids as starting material and substantially without the formation of any by-products, wherein a) first, a stoichiometric salt is formed from the tetracarboxylic acid and the tetraamine; b) polycondensation is carried out under hydrothermal conditions by heating the stoichiometric salt obtained in step a), in water as a solvent and under pressure, to temperatures above 100° C.