In radical polymerization of monofunctional monomers, addition fragmentation chain transfer (AFCT) agents are well known to regulate polymerization and yield polymers with lower molecular weights and narrower molecular weight distributions. Papers concerning bulk photopolymerization of monomer mixtures with AFCT agents are rarely found in literature. In this article, AFCT reagents based on b-allyl sulfones with different vinyl activating groups were synthesized and compared. The compounds were tested in mono-and difunctional monomer systems providing information about the influence on photoreactivity, molecular weight, as well as thermal and mechanical properties of the resultant polymers. Where more potent activating groups (-Ph, -CN) markedly influenced polymerization at lower concentrations, the AFCT reagent with an ester activating group reacted at a similar rate to the methacrylate monomer (C T % 1) and provided the best overall performance.

Photopolymerization of (meth)­acrylate-based formulations has become a widespread method for industry due to the high energy efficiency and low curing times of this technology. Various products from simple coatings to more complex applications such as additive manufacturing technologies are based on this versatile method. Common industrial radical photoinitiators are generally based on aromatic ketones with the benzoyl chromophore as the key constituent. In medical or food packaging applications, residual photoinitiator or photoproducts migrating into the product have to be avoided, particularly for toxicological reasons. In this paper we present a new generation of nonaromatic initiator systems. Besides their good reactivity in (meth)­acrylic formulations, they show good bleaching properties and high biocompatibility.

Migration of photoinitiators and their photoproducts are a major problem when it comes to food packaging or applications in the medical sector. Frequent coincidence with leachables and humans can be problematic, especially over time. Therefore, a new class of biocompatible photoinitiators, the aliphatic α‐ketoesters, were selected to be immobilized. Biocompatibility and low leaching were achieved using the metabolite α‐ketoglutaric acid. Immobilization of the photoinitiator is obtained via a macromolecular or copolymerizable approach.