Research output: Contribution to journal › Article › peer-review
Primary Radical Cations in Irradiated Poly(isobutylene). / Borovkov, Vsevolod I.; Potashov, Pavel A.; Beregovaya, Irina V. et al.
In: Journal of Physical Chemistry B, Vol. 124, No. 32, 13.08.2020, p. 7059-7066.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Primary Radical Cations in Irradiated Poly(isobutylene)
AU - Borovkov, Vsevolod I.
AU - Potashov, Pavel A.
AU - Beregovaya, Irina V.
AU - Shchegoleva, Lyudmila N.
AU - Molin, Yuri N.
PY - 2020/8/13
Y1 - 2020/8/13
N2 - 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.
AB - 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.
KW - ELECTRON-SPIN-RESONANCE
KW - BRANCHED ALKANES
KW - POLYISOBUTYLENE
KW - FLUORESCENCE
KW - DEGRADATION
UR - http://www.scopus.com/inward/record.url?scp=85089610626&partnerID=8YFLogxK
U2 - 10.1021/acs.jpcb.0c03280
DO - 10.1021/acs.jpcb.0c03280
M3 - Article
C2 - 32678602
AN - SCOPUS:85089610626
VL - 124
SP - 7059
EP - 7066
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
SN - 1520-6106
IS - 32
ER -
ID: 25304033