Chapter 2: Long-wavelength-sensitive Radical Photoinitiators

This chapter reports the application of different organic compounds as photosensitizers for selected types of co-initiators. These chromophores possess strong absorption bands at wavelengths ranging from 300 to 850 nm and are shown to facilitate photoinitiated radical polymerization of acrylates, for example 2-ethyl-(2-hydroxymethyl)-1,3-propanediol triacrylate (TMPTA) and 1,6-hexanediol diacrylate (HDDA), and sometimes also the cationic polymerization of epoxides. The polymerizations are initiated at room temperature by using long-wavelength visible light in the presence of borate salts, aliphatic and aromatic amines, iodonium salts, N-alkoxypyridinium salts, 1,3,5-triazine derivatives and silane compounds acting as co-initiators.