Structure, Thermal Properties and Proton Conductivity of the Sulfonated Polyphenylquinoxalines

Аnna V Pisareva; Natalia М Belomoina; Еlena G Bulycheva; Мikhail М Ilyin; Evgeniya Y Postnova; Rostislav V Pisarev; Tatiana S Zyubinа; Аlexander S Zyubin; Alexander I Karelin; Yury А Dobrovolsky

doi:10.3390/membranes12111095

Structure, Thermal Properties and Proton Conductivity of the Sulfonated Polyphenylquinoxalines

Membranes (Basel). 2022 Nov 3;12(11):1095. doi: 10.3390/membranes12111095.

Affiliations

¹ Federal Research Center of Problem of Chemical Physics and Medicinal Chemistry RAS, 142432 Chernogolovka, Russia.
² Nesmeyanov Institute of Organoelement Compounds RAS, 119334 Moscow, Russia.
³ Osipyan Institute of Solid State Physics RAS, 142432 Chernogolovka, Russia.

Abstract

This paper briefly reviews the results of scientific research on the proton conductivity of sulfonated polyphenylquinoxalines. Synthesis, structure (IR spectroscopy, SEM, quantum-chemical modeling, molecular weight distribution), moisture capacity, thermal properties, and proton conductivity of sulfonated polyphenylquinoxalines (sulfur content 2.6, 4.2, 5.5, and 7%) were studied. The relative stable configurations of sulfonated polyphenylquinoxalines with different positions of benzene rings and sulfogroups with the help of quantum chemical modeling were modeled. Sulfonation of the starting polyphenylquinoxalines was confirmed by IR spectroscopy and elemental analysis. The SEM method was used to study the surface of sulfonated polyphenylquinoxalines, and sulfonation regions were found. It was shown that sulfonated polyphenylquinoxalines contain water and are stable up to 250 °C; on further heating, the decomposition of the sulfogroups occurs. The conductivity of the obtained polymer electrolytes was studied by impedance spectroscopy, and long-term tests were carried out. It is shown that the proton conductivity at an ambient humidity of 98 rel. % reaches values 10^-6-10^-3 S/cm depending on the degree of sulfonation. It was shown that even after long-term storage in air (7 years), samples of sulfonated polyphenylquinoxalines with a high sulfur content of 7% at 98% air humidity have a conductivity of 8 × 10^-4 S/cm.

Keywords: conductivity; degree of sulfonation; quantum chemical modeling; structure; sulfonated polyphenylquinoxalines; thermal stability.

Grants and funding

The work was carried out on the topic of the State assignment of the Ministry of Science and Higher Education of the Russian Federation, state registration number AAA-A19-119061890019-5.