Free radical macrophotoinitiators: an overview on recent advances

Photocrosslinkable Polymers for Biomedical Applications

“…In order to obtain crosslinked polymers, it is necessary to generate free radicals in the system that will induce a free radical chain polymerization of monomers and oligomers. Both have reactive functional groups that can be activated under the presence of reactive radicals, resulting in the formation of crosslinked structures (Corrales et al, 2003). In the mechanism involved in the process we can consider three main reactions: initiation, propagation and termination.…”

Synthesis and characterization of poly(vinylchloride) type macrophotoinitiator comprising side-chain thioxanthone via click chemistry

“…Due to the advantages of macromolecules in comparison to low molecular weight analogues, significant developments are described in the synthesis of macrophotoinitiator. These developments can be arranged as energy saving, low volatility, very short cure time and higher activity [1][2][3]. Types of free radical photoinitiators can be divided into two classes, according to their radical generation mechanisms, namely cleavage-type (Type I) (benzoin ether, acylphosphine oxides) initiators undergo a very rapid bond cleavage after absorption of a photon on the other hand, type II initiators form relatively long-lived excited triplet states capable of undergoing hydrogen-abstraction or electron-transfer reactions with co-initiator molecules that are deliberately added to the monomer containing system [4].…”

“…The reaction heat liberated in the polymerization was directly proportional to the number of acrylate reacted in the system. By integrating the area under the exothermic peak, the conversion of the acrylate groups (C) or the extent of the reaction was determined according to Equation (1): (1) where "H t is the reaction heat evolved at time t, and "H 0 theory is the theoretical heat for complete conversion. "H 0 theory = 19.2 kcal·mol -1 for an acrylate bond [29].…”

Synthesis of Novel Well-defined End-functional Macrophotoinitiator of Poly(ε-caprolactone) by Ring-opening Polymerization

“…Many side-and main-chain photoinitiators have been synthesized and their photochemistry and utilization in both applications have been reviewed extensively. [2][3][4][5][6][7][8] Polymeric photoinitiators containing terminal photoactive benzoin groups by using azo-benzoin initiators were synthesized by Yagci et al [6][7][8] The thermal treatment of these initiators in the presence of styrene (St) leads to benzoin groups at both ends of polystyrene chain, as polystyryl radicals tend to terminate via recombination (Scheme 1).…”