Active sites of gamma-irradiated silica initiating surface polymerization of tetrafluoroethylene

Citation
Si. Kuzina et al., Active sites of gamma-irradiated silica initiating surface polymerization of tetrafluoroethylene, RUSS J PH C, 75(8), 2001, pp. 1355-1360
Citations number
20
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY
ISSN journal
00360244 → ACNP
Volume
75
Issue
8
Year of publication
2001
Pages
1355 - 1360
Database
ISI
SICI code
0036-0244(200108)75:8<1355:ASOGSI>2.0.ZU;2-O
Abstract
EPR and low-temperature calorimetry were used to demonstrate that active si tes of ionic type are responsible for the initiation of the postradiation p olymerization of tetrafluoroethylene at the surface of a macroporous glass. A heat-release peak in the DSC curve within 180-220 K was attributed to po lymerization. The presence in of spectral features belonging to the termina l similar to CF2-CF2. radical in the EPR spectrum of the system suggests th at polymer chains grow by the radical mechanism. It was assumed that the fi rst stage of the polymerization is the formation of radicals by the interac tion between ionic species of the silica support and adsorbed monomer molec ules.