Photoinitiating behavior of benzophenone derivatives covalently bonded tertiary amine group for UV-curing acrylate systems

Abstract

A series of benzophenone derivatives (N-BPs) containing tertiary amine group used as hydrogen abstraction-type (type II) photoinitiators were synthesized through the addition reaction of secondary amines with 4-(2,3-epoxypropyloxy) benzophenone. The chemical structures were characterized with 1H NMR, FTIR spectroscopy, and UV spectrum measurements. The N-BPs showed the higher absorption in 300–400 nm than benzophenone (BP). The photoinitiating activity was examined based on the photopolymerization of 1,6-hexanediol diacrylate using photo-DSC method. The results showed that the photoinitiating efficiency was negatively affected by the molecular structure of alkyl group connected to the tertiary amine with the order of isopropyl (N-BPI) < methyl (N-BPM) < ethyl (N-BPE) < propyl (N-BPP). Moreover, the diethanolamine-modified benzophenone derivative (N-BPOH) had the highest-photoinitiating efficiency for free radical polymerization systems among the N-BPs. Copyright © 2011 John Wiley & Sons, Ltd.