A novel series of linear, high molecular weight polymers were synthesized by one-pot,
superacid-catalyzed reaction of acenaphthenequinone (1) with aromatic hydrocarbons. The reactions were
performed at room temperature in the Brønsted superacid CF3SO3H (trifluoromethanesulfonic acid, TFSA)
and in a mixture of TFSA with methanesulfonic acid (MSA) and trifluoroacetic acid (TFA), which was
used as both solvent and a medium for generation of electrophilic species from acenaphthenequinone.
The polymer-forming reaction was found to be dependent greatly on the acidity of the reaction medium,
as judged from the viscosity of the polymers obtained. Polycondensations of acenaphthenequinone with
4,4‘-diphenoxybenzophenone (f), 1,3-bis(4-phenoxybenzoyl)benzene (g), 1,4-bis(4-phenoxybenzoyl)benzene
(h), 1,10-bis(4-phenoxyphenyl)decane-1,10-dione (i), 2,6-diphenoxybenzonitrile (j), 2,6-diphenoxybenzoic
acid (k), and 2-(4-biphenylyl)-6-phenylbenzoxazole (l) proceeded in a reaction medium of wide range of
acidity, including pure TFSA (Hammett acidity function H
0 of pure TFSA is −14.1), whereas condensation
of 1 with biphenyl, terphenyl, diphenyl ether, and 1,4-diphenoxybenzene needed a reaction medium of
acidity H
0 less than −11.5. A possible reaction mechanism is suggested. The polymers obtained were
found to be soluble in the common organic solvents, and flexible transparent films could be cast from the
solutions. 1H and 13C NMR analyses of the polymers synthesized revealed their linear, highly regular
structure. The polymers also possess high thermostability. Char yields for polymers 3a, 3c, 3d, and 3l in
nitrogen were close to 80% at 1000 °C.