Chemical Oxidative Condensation of Benzidine in Non-Aqueous Medium: Synthesis and Investigation of Oligomers and Polymer with Benzidine Diimine Units.

Ranush Durgaryan,Narine Durgaryan

doi:10.3390/polym14010034

Abstract

The oxidative condensation of benzidine has been carried out in acetic acid media using potassium peroxydisulfate as the oxidizing agent. Using different monomer–oxidant molar ratios, benzidine dimer, trimer, and polymer have been synthesized for the first time. It was established that the polybenzidine structure is composed from a sequence of benzidinediimine and diphenylene units with amino/amino end groups and thus proves the possibility of ammonia elimination during the oxidative polymerization of aromatic diamines. The method seems to be common for the synthesis of polymers with the sequence of aromatic diimine and arylene units. TGA analysis of the obtained trimer and polymer was investigated, and the high thermostability of both the polymer and trimer was revealed. According to the obtained data, both polymer and trimer matrix decomposition started at 300 °C, and at 600 °C, 75.94% and of 69.40% of the initial weight remained, correspondingly. Conductivities of the polymer and trimer show a semiconductor-type change from temperature and after doping show an increase in conductivity up to 10−4 Sm/cm.

Highlights

Polyaniline (PANi) and the polymers synthesized from aromatic diamines occupy a special place among electroactive conjugated polymers due to their good environmental stability, easy and a cheap method of synthesis, unique properties, and varied application [1,2,3]
In principle, all aromatic diamines can be oxidized into polymers, but from the large range of diamines considered in review, only a few monomers—typically o,m,p-phenylenediamines and 1.5-diaminonaphthaline—have been successfully polymerized using chemical oxidative polymerization
The syntheses of model compounds on the base of Bnz were performed by the same method as for oligomers of pPhDA, i.e., a molar ratio of 4 to 1 of monomer to potassium persulfate was used in glacial acetic acid medium at temperature of 15 ◦ C

Summary

Introduction

Polyaniline (PANi) and the polymers synthesized from aromatic diamines occupy a special place among electroactive conjugated polymers due to their good environmental stability, easy and a cheap method of synthesis, unique properties, and varied application [1,2,3]. The oxidative polymerization of aromatic diamines, including benzidine (Bz), were summarized in a well-done informative review of Chinese scientists [3]. As it was mentioned, in principle, all aromatic diamines can be oxidized into polymers, but from the large range of diamines considered in review, only a few monomers—typically o-,m,p-phenylenediamines and 1.5-diaminonaphthaline—have been successfully polymerized using chemical oxidative polymerization. The main investigations on oxidative polymerization and copolymerization of Bnz have been done by using the electrochemical method, and benzidinedimine formation was identified [7,8,9,10,11,12]. No structural identifications were done for the resulting polymers in [11], and in [7], it was mentioned that the most probable are

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Conclusion