Abstract: Using the method of time-resolved magnetic field effect in radiation-induced fluorescence, primary radical cations (RCs) in irradiated poly(isobutylene) (PIB) have been detected for the first time. A comparison of experimental results with the data of quantum chemical calculations suggests that the initial geometry of the ionized fragment of the PIB molecule is close to the geometry of the neutral polymer in the trans-gauche-trans-gauche conformation. The spin density of the RC in this geometry is delocalized over more than 10 polymer units, and the width of the RC's EPR spectrum is about ΔHpp ≈ 1.3 mT. At a temperature of 273 K and lower, the lifetime of the primary RCs with the delocalized spin density exceeds 10 ns. The structural relaxation of the RCs results in the spin density localization on a single C-C bond, which is extended to nearly 0.2 nm, and in the increase in the EPR spectrum width to ΔHpp ≈ 2.4 mT. It looks likely that this intramolecular structural relaxation is coupled strongly with those types of molecular motions that determine the process of dielectric β-relaxation in the polymer. Copyright © 2020 American Chemical Society.

Cite: Borovkov V.I. , Potashov P.A. , Beregovaya I.V. , Shchegoleva L.N. , Molin Y.N.
Primary Radical Cations in Irradiated Poly(isobutylene)
Journal of Physical Chemistry B. 2020. V.124. N32. P.7059-7066. DOI: 10.1021/acs.jpcb.0c03280 WOS Scopus РИНЦ

Dates:

Published online:	Jul 17, 2020
Published print:	Aug 13, 2020

Identifiers:

Web of science	WOS:000562943100012
Scopus	2-s2.0-85089610626
Elibrary	45393581
OpenAlex	W3043359492

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