ELECTRON-SPIN RESONANCE STUDY ON POLYMERIZATION OF ALKYL ACRYLATES WITH NORMAL-BUTYL TITANATE(IV)-TRIETHYLALUMINUM CATALYST

Experimental data are presented which show that n-butyl titanate(IV)- triethylaluminum catalyst at Al/Ti molar ratios greater than 6 polymerizes methyl and n-butyl acrylates at minus 78 degree C. The polymerization system which includes methyl acrylate at minus 78 degree C, gives two ESR signals with g factors of 1. 958 and 1. 961 that overlap each other. The absorption intensity of the latter signal is approximately proportional to the polymer chain concentration calculated from polymer yield and the molecular weight. The polymerization system at Al/Ti ratios smaller than 3 has no catalytic activity on the polymerization and shows only the ESR signal with the g factor of 1. 958. On the basis of these facts the ESR signal with the g factor of 1. 961 is attributed to the active growing end of poly(methyl acrylate) with this catalyst. The character of this active growing end is discussed.