SYNTHESIS AND INVESTIGATION OF PROPERTIES OF POLYETHERNAFLUYLENEBENZIMIDAZOLES USING REACTION OF NUCLEOPHILIC POLYNITRO-SUBSTITUTION
Authors: Kumykov Ruslan M. , Kyarov Aslan A. 
Published: November 2019

Soluble polyethernaftoylenbenzimidazoles (PENBI) not previously described are obtained by reacting bis (nitronaphthoylenbenzimidazole) arylene with bisphenols using nucleophilic polynitrosubstitution reaction. The synthesis conditions and the influence of the introduced "bridge" flexible ether, dichloroethylene and carbonyl groups between the phenyl cores of the central fragments of macromolecules on the solubility, thermal and strength properties of the synthesized polymers were studied. Improving melting and solubility (PENBI) without a significant effect on the thermal and strength characteristics is achieved by introducing naphthylamide cycles into them, in combination with flexible bridging fragments into macromolecules of target polymers. The initial bis (nitronaphthoylenbenzimidazole) arylenes were obtained on the basis of (3 or 4-nitronaphthalic anhydride) and bis (o-phenylene diamines), which are derivatives of chloral. In this aspect, the bis (o-phenylenediamine) and bis (nitronaphthoylenenbenzimidazole) arylenes synthesized by us are unique, both in terms of availability of raw materials and price. Bis (nitronaphthoylenbenzimidazole) arylenes were obtained by the interaction of two moles (3 or 4-nitronaphthalic anhydride) with one mole of bis (o-phenylenediamine) under conditions of high-temperature catalytic cyclocondensation in organic solvents. All reactions of the synthesis of bis (nitronaphthoylenbenzimidazole) arylene proceeded homogeneously and resulted in well-cyclized dinitro compounds. As a comonomer of bis (nitronaphtho-ylenbenzimidazole) arylenes, bis-phenols containing also flexible “bridge” groups between phenyl nuclei were used in the synthesis of polyethernaphthoylenbenzimidazoles. The synthesis of polyethernaphthoylenebenzimidazoles was carried out by the interaction of bis (3 or 4-nitronaphthylenebenzimidazole) arylenes with bis-phenols under mild conditions in dimethyl sulfoxide or its mixture with toluene at a temperature of 70 ° C for 2 h in an absolutely dry environment.  The obtained composite polymers were well soluble in dipolar aprotic solvents and had a rather wide interval between the temperatures of active destruction and softening temperatures (~ 250-260 ° С). Analysis of the primary thermal characteristics of the obtained polymers showed that they are characterized by relatively high temperatures of destruction (510-550 ºС). Polyethernaphthoylenebenzimidazoles are amorphous: this fact, combined with the presence in the macromolecules of a large number of flexible and “hinged” groups, determine their increased solubility in chlorinated and phenolic solvents. The significant difference between the softening temperature and the temperature of active destruction determines the possibility of their processing into products by injection molding. An analysis of the fire resistance of polymers showed that the highest oxygen index is for polymers, where macromolecules contain more dichloroethylene groups (KI = 62), and the lowest - for polymers with a high oxygen content (OI = 38.3).