EPR/ENDOR Study of the Decay of Trapped Radicals in Photopolymerized Butane-1,4-diol Diacrylate

l.nng-livcd Impped rndlcals prodnced during Ihe pholopolymerizalion ' or bulane-I,4-diol diaCT}'1I1te (DODA) were studied b}' EPR aod ENOOR speclro 'coPY IInd tbcir Ihermul dCCll)' "'us followed by EPR measuremeob al different Icrnpenilures (40-120 °(:) l'or killelic ~tud). The EPR signal ~howcd !he superimposition 01' Iwo dill'erenl poHems, Il Ihree-line nnd a single-line speclrum. BOlh EPR pllllcrns decayed following flrsl-ordcr kinelics in Ihe investigated lemperalure mnge. Aclh'alion parameters of the d~cay were ublained. rIle EPR pnllern werc nllribulcd III Ihe same radical species silllaled in l1uid and in eros -lillked regions Clf Ihe phOIOpol}meriLCd BODA. Radicals 01' Ihe lalter kind undergo eleclron spin exchange slrong enough lo wasll out the h)'perfine splilling. The single-lIne widlh is mainly determjDed by electron spin dipole-dipole inleractioos. Thl' ENDOR re~ponse is unI)' of Ihe malrix killd, t~'pic,,1 o\' radicals in a solid pllase. l'hl' preseol model WAS 9150 compured with receDI titeralure rep(lns.