Radicals trapped during the photopolymerization and photo-cross-linking of 2-ethyl-2-hydroxymethylpropane-1,3-diol triacrylic ester have been studied by EPR spectroscopy at different temperatures (25-180-degrees-C) and their thermal decay has been followed at 120-degrees-C and 150-degrees-C. Performing a fitting procedure on the EPR signals showed that they are composed of two kinds of patterns, which superimpose with the same g value. One of them is a single-line spectrum, while the other is hyperfine-structured. An exchange between two radical conformations is revealed by the latter, with the rate depending both on temperature and on the molar fraction of radicals giving the single-line spectrum. This suggests that both species are involved in the exchange mechanism. Termination occurs preferentially between radicals giving the same EPR pattern. Second-order termination rate constants depend on the photoinitiator concentration in the irradiated photoreactive mixture and give information about the microstructure of the polymer.
ELECTRON-PARAMAGNETIC-RESONANCE CHARACTERIZATION AND THERMAL DECAY OF RADICALS TRAPPED IN A PHOTOPOLYMERIZED TRIACRYLATE MONOMER / E. SELLI, C. OLIVA, A. GIUSSANI. - In: JOURNAL OF THE CHEMICAL SOCIETY. FARADAY TRANSACTIONS. - ISSN 0956-5000. - 89:23(1993), pp. 4215-4219.
Titolo: | ELECTRON-PARAMAGNETIC-RESONANCE CHARACTERIZATION AND THERMAL DECAY OF RADICALS TRAPPED IN A PHOTOPOLYMERIZED TRIACRYLATE MONOMER |
Autori: | SELLI, ELENA (Primo) OLIVA, CESARE (Secondo) |
Settore Scientifico Disciplinare: | Settore CHIM/02 - Chimica Fisica |
Data di pubblicazione: | 1993 |
Rivista: | |
Tipologia: | Article (author) |
Digital Object Identifier (DOI): | http://dx.doi.org/10.1039/ft9938904215 |
Appare nelle tipologie: | 01 - Articolo su periodico |