REACTIVITY OF RADICALS FROM 1-(N,N-DIMETHYLAMINO)ETHYLENE-2-DERIVATIVES IN THE ACRYLIC PHOTOPOLYMERIZATION

Relative reactivities of radicals derived from several 1-(N,N-dimethyl amino)ethylene-2-derivatives towards the polymerization of butyl acryl ate have been calculated. It has been observed that the reactivity of the radicals increases as the electron withdrawing character of the gr oups attached in the beta position to the N atom increases. The experi mental efficiency factor (f) has been found to be proportional to the sigma(F) value defined in the Taft equation. The dependence of the rea ctivities with the nature of the radicals has also been explained thro ugh their frontier orbital characteristics. The presence of heteroatom s next to the radical center could modify, in some cases, the accuracy of these calculations, although the inclusion of more sophisticated q uantum-mechanical methods does solve this drawback. Moreover, the enth alpy calculation of the possible radicals formed from a certain molecu le gives a good approach to realize about the existence of anomalous b ehaviors. (C) 1997 John Wiley & Sons, Inc.