Radical photopolymerization is - with respect to economic and environmental viability - an excellent technique to prepare coatings on paper, carton, wood, polymers or metal within the fraction of a second, without the use of organic solvents. Furthermore, also specialized applications, like stereolithography, rapid prototyping, dental fillings or tissue engineering were added to this portfolio during the recent years. However, two major challenges related to the commonly used photoinitiators are the oxygen inhibition and the evolution of potentially noxious compounds from the cured material. The aim of this PhD-thesis was to overcome these limitations by the development of more efficient and “safe” photoinitiating systems with an UV-cleavable N-O bond, which advance the use of photopolymerization in sensitive areas like food packaging and medicine. Moreover, novel phosphate-containing polymers were developed for biomedical applications, which revealed very good biocompatibility and mechanical strength almost resembling human bone.