2020 (3) 7

https://doi.org/10.15407/polymerj.42.03.218
Investigation of the formation of Ti3+-centers under the action of uv radiation of Ti-containing interpenetrating polymer networks by EPR method

T.T. Alekseeva,
Institute of Macromolecular Chemistry NAS of Ukraine, 48, Kharkivske shose, Kyiv, 02160, Ukraine
E-mail: tatianalekseeva49@gmail.com
N.V. Kozak,
Institute of Macromolecular Chemistry NAS of Ukraine, 48, Kharkivske shose, Kyiv, 02160, Ukraine
E-mail: kozaksmalt@ukr.net
ORCID: 0000-0001-6200-4048
N.V. Yarova,
Institute of Macromolecular Chemistry NAS of Ukraine, 48, Kharkivske shose, Kyiv, 02160, Ukraine
E-mail: ynv25@ukr.net
ORCID: 0000-0002-3347-8073
Polym. J., 2020, 42, no. 3: 218-225.
Section: Structure and properties.
Language: Ukrainian.

Abstract:

Ti-containing interpenetrating polymer networks (Ti-IPNs) based on the cross-linked polyurethane, poly (hydroxyethyl methacrylate) and poly (titanium oxide) have been synthesized. First poly (titanium oxide) was synthesized by sol-gel method in the presence of 2-hydroxyethyl methacrylate at different molar ratio of Ti(OPri)4/H2O. The results of optical spectrophotometry show that the light transmission coefficients (T, %) of titanium-containing interpenetrating polymer networks were of 90,7–91,0 % at λ=650 nm. According to EPR data, UV irradiation in the air at room temperature of Ti-IPN samples is accompanied by appearance of signal of paramagnetic centers with broad isotropic signal at g1= 2,010 and also noticeably splitted signals at g2 = 2,003 and g3 =1,967. First and second of them can be ascribed to the oxygen-containing “hole scavenger”, while the third one is associated with the Ti3+ paramagnetic ions. The low rate of the electron–hole pair recombination at room temperature in the air demonstrates efficient separation of the charged particles in the hybrid material. Using nitroxyl spin probe (SP) it was revealed that UV-induced charge separation and subsequent charge recombination in Ti-IPNs is accompanied by compaction of macro chains in the hybrid system analysed. The observed changes in the permeability of the Ti-IPN for nitroxyl SP correlate with the measurements of the specific density and the results of the DSC for determining the heat capacity increment (ΔC).

Keywords: Poly (titanium oxide), Titanium-containing interpenetrating polymer networks, UV-irradiation, signal of paramagnetic centers, nitroxyl spin probe.

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