New polymeric UV photoinitiators, bearing the benzoin methyl ether moiety linked to the side chain through the 4 0 position, were synthetized by radical homopolymerization of the corresponding monomers, 4 0 -methacryloyloxy benzoin methyl ether and 4 0 -methacryloyloxy a-methyl benzoin methyl ether, prepared in turn after a thorough investigation of synthetic methods. For comparison, low molecular weight structural models of the repeating co-units of the polymers having the pivaloyloxy group linked to the 4 0 position of the benzoin methyl ether moiety were also prepared. All polymeric and model compounds were fully characterized and employed in the photoinitiated polymerization and crosslinking of a standard acrylic formulation for clear UV curable coatings. The photoinitiating activity of these systems, measured by microwave dielectrometry, indicates a higher cure fastness for the model compounds with respect to the corresponding polymeric derivatives, and such a behaviour is tentatively interpreted in terms of the fragmentation mechanism of the benzyl methyl ether radicals formed on a-photocleavage of the benzoin moiety.
Посилання на статтю:
Polymeric photoinitiators having benzoin methylether moieties connected to the main chain through the benzyl aromatic ring and their activity for ultraviolet-curable coatings / L. Angiolini, D. Caretti, C. Carlini, E. Corelli, E. Salatelli // Polymer. – 1999. – N 40. – P. 7197–7207.