Synthesis and photoinitiated polymerization of a new urethane acrylate monomer: influence of polymerization temperature

The synthesis of a new urethane acrylate monomer (UAM) from hexamethylene d iisocyanate trimer (HDT) and 2-hydroxyethyl methacrylate was performed by c lassical condensation. Physicochemical and thermal characterization of UAM was investigated (<(Mn)over bar> = 1480 g mol(-1); T-g = -38 degrees C) and no secondary reactions were observed. The photoinitiated polymerization of UAM with 2,2-dimethyl-2-hydroxy acetophenone (Darocur 1173) as radical pho toinitiator was studied by using thermal photocalorimetry at different temp eratures. Photoinitiator concentration (0.15% w/w) and light intensity (2.7 mW cm(-2)) were kept constant. The maximum conversion was obtained at 70 d egrees C. Above this temperature, thermal polymerization interfered with th e photocalorimetric measurements. (C) 1999 Elsevier Science B.V. All rights reserved.