Russian Chemical Bulletin, International Edition, Vol. 67, No. 10, pp. 1903—1907, October, 2018
1903
Polyheteroarylenes based on 2,3,7,8-tetraaminodibenzo-p-dioxin
and aromatic polyfunctional carboxylic acids
D. M. Mognonov,a O. Zh. Ayurova, O. V. Il´ina, and V. V. Khakhinov
a
a
b
aBaikal Institute of Nature Management, Siberian Branch of the Russian Academy of Sciences,
6
ul. Sakhyanovoy, 670047 Ulan-Ude, Russian Federation.
Fax: +7 (301) 243 4753. E-mail: info@binm.ru
b
Buryat State University,
2
4a ul. Smolina, 670000 Ulan-Ude, Russian Federation.
Fax: +7 (301) 221 0588. E-mail: univer@bsu.ru
Polynaphthoylene benzimidazole and polybenzimidazole were obtained via polycondensa-
tion of 2,3,7,8-tetraaminodibenzo-p-dioxin with aromatic di- and tetracarboxylic acids in
polyphosphoric acid. From a solution of polynaphthoylene benzimidazole in methanesulfonic
acid a heat-resistant fiber with high tensile strength was obtained. Aromatic polybenzimidazoles
are promising materials for producing membranes of medium-temperature fuel cells.
Key words: 2,3,7,8-tetraaminodibenzo-p-dioxin, isophthalic acid, terephthalic acid,
1
,4,5,8-naphthalenetetracarboxylic acid dianhydride, polynaphthoylene benzimidazole, poly-
benzimidazoles, polycondensation, solubility, thermal stability, mechanical properties, proton
conductivity, heat-resistant fibers.
Modern science and engineering require novel poly-
meric materials which can be used when exposured to high
temperatures, mechanical stress, radiation, chemicals,
solvents, and oils. When solving practical problems, one
often should take account of the joint effect of some of the
above factors. Over the last years, novel polyheteroarylenes
have been synthesized, leaving polymeric materias based
on known thermoreactive resins in thermal stability far
drolytic media along with their stiffness, elasticity, and
good electric properties make these polymers promising mat-
erials for applications such as adhesives, coatings, film
materials, fibers, and layered plastics. Furthermore, it is poss-
ible to use PBIs as polymeric membrane materials to create
alternative energy sources, since being doped with phos-
phoric acids, these materials develop proton conductivity
and are able to retain it under heating up to 160—200 С.
The present study is aimed on developing synthetic
approaches to ladder polynaphthoylene benzimidazol
(PNBI) and aromatic polybenzimidazols on the basis of
2,3,7,8-tetraaminodibenzo-p-dioxin and aromatic di- and
tetracarboxylic acids.
1
—7
behind.
Particular attention of researches is drawn to polymers
the molecules of which are constructed from two cross-
linked chains. Since such structure resembles a rope ladder,
8
—13
these polymers are often referred to as ladder ones.
Interest expressed to the ladder polymers is non-casual.
Under exposure to adverse factors, cleavage of a chemical
bond in a ladder polymer does not yet decrease the mo-
lecular weight (MW) as in linear polymers. A decrease in
MW takes place only when at least two bonds located in
the same ring are cleaved. Moreover, the probability of
radical recombination for ladder polymer is higher due to
Experimental
Naphthalene-1,4,5,8-tetracarboxylic dianhydride was puri-
fied by recrystallization from acetic anhydride. Terephthalic and
isophthalic acids (chemically pure) were used as purchased.
2,3,7,8-Тetraaminodibenzo-p-dioxin was obtained according
to Scheme 1.
4
the cage effect. This fact is supported by results of Monte-
Dibenzo-p-dioxin (2) was obtained by thermal condensation24
of о-chlorophenol (0.20 mol) in the presence of anhydrous potas-
sium carbonate (15 g) and ultrafine copper powder (2 g) under
constant stirring at 170—180 С for 6—8 h. After cooling the
reaction mixture to 20 С, 20% NaOH aqueous solution was
added thereto. Filtrated dibenzo-p-dioxin was precipitated with
ethanol and recrystallized from benzene. Crystalline white prod-
uct melts at 118—121 С (see Ref. 24: 120—121 С). The yield
was 45% (on о-chlorophenol basis).
Carlo prediction calculations14 according to which the
molecular weight of linear polymers under adverse conditions
is decreased far more rapidly than that of the ladder ones.
Previously, high molecular weight aromatic polybenz-
imidazoles (PBIs) were synthesized by heating mixtures
of aromatic tetramines and aromatic dicarboxylic acid
diphenyl esters at high temperatures.1
—3,6,7,15—23
Thermal
stability of PBIs and their high resistance to various hy-
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1903—1907, October, 2018.
066-5285/18/6710-1903 © 2018 Springer Science+Business Media, Inc.
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