Investigation of diacrylate-based cyclopolymerizable monomers in photopolymerization

Abstract

In 1949, the thermally radical-induced cyclopolymerization of diallyl quaternary ammonium salts was reported the first time.1 Thereby, difunctional enes undergo an alternating intra-inter molecular cyclization polymerization leading to rings in the linear polymer backbone. Since then, further substances have been discovered that were used as cyclopolymerizable monomers (CPMs) in thermally-induced radical polymerization.2 However, in the field of photopolymerization only a few references of using cyclopolymerization have been published.3,4

This work focuses on the use of diacrylates as CPMs regarding their application in radical induced photopolymerization. As can be seen in Figure 1, a variety of different diacrylate-based CPMs with different side groups (R) was synthesized5 and investigated regarding their application in photopolymerization. The synthesized CPMs were homopolymerized as well as copolymerized with methacrylates and acrylates. Reactivity studies performed on a photo-DSC and photo-rheology discovered a difference in photoreactivity and copolymerization behavior of the tested CPMs. The best performing CPM was chosen to be used in combination with a difunctional acrylate to form networks. The transparent photopolymers containing different amounts of CPM were then mechanically tested (DMA, tensile test).