C. Oliva et al., ELECTRON-PARAMAGNETIC-RESONANCE AND ELECTRON-NUCLEAR DOUBLE-RESONANCECHARACTERIZATION OF RADICALS IN PHOTOPOLYMERIZED MULTIFUNCTIONAL METHACRYLATES, Perkin transactions. 2, (12), 1995, pp. 2133-2139
Propagation radicals generated during the photopolymerization and phot
o-cross-linking of a trimethacrylate and a vinylmethacrylate monomer h
ave been characterized by EPR and ENDOR spectroscopy at different temp
eratures. Also, radical decay has been investigated at 363-423 K. The
EPR spectral shape reflects a fast exchange process between two radica
l conformations and is sensitive to the mobility of the polymeric stru
cture surrounding radicals. ENDOR spectra show H-1-matrix lines and a
band around 45 MHz, which has been attributed to the interaction of th
e unpaired electron with the hydrogen nuclei of a freely rotating meth
yl group. Radical decay and dynamic phenomena involving radicals have
been interpreted in the light of a dispersive kinetic model, which all
ows the evaluation of useful parameters for polymer characterization.