Daikos, Olesya; Naumov, Sergej; Knolle, Wolfgang; Heymann, Katja; Scherzer, Tom published the artcile< Peculiarities of the photoinitiator-free photopolymerization of pentabrominated and pentafluorinated aromatic acrylates and methacrylates>, Electric Literature of 71195-85-2, the main research area is photopolymerization pentabrominated pentafluorinated aromatic acrylate methacrylate.
Pentabrominated and fluorinated aromatic (meth)acrylates as well as their non-halogenated counterparts have been studied with the aim to avoid conventional photoinitiators and to overcome some neg. consequences related to their use. Therefore, RTIR spectroscopy, laser flash photolysis and GC/MS were utilized. Even low concentrations (1 to 5 wt%) of brominated (meth)acrylates in the model varnish lead to initiation of a photopolymerization reaction under exposure to UV light with æµ?> 300 nm. This is due to the fact that excitation of the aryl moiety leads to the homolysis of bromine-Ph bonds with a high quantum yield of é?.15-0.3. Both, bromine radicals released from either ortho, meta or para position as well as the corresponding tetrabromoaryl radicals, may initiate the polymerization of brominated aromatic (meth)acrylates. In contrast, fluorinated aromatic (meth)acrylates undergo æµ?cleavage of the carboxyl group (as in the case of non-halogenated aromatic (meth)acrylates), if excitation of the acrylic double bonds is done with UV-C light (æµ?< 280 nm). Radical formation occurs with a comparable quantum yield of 0.1-0.22 (fluorinated) and 0.16-0.36 (non-halogenated compounds), despite the different pathway of fragmentation. Thus, in all cases the efficiency of initiation is comparable to conventional photoinitiators. Quantum chem. calculations of orbitals involved and of the Gibbs free energy of transients and products support the suggested reaction pathway. Physical Chemistry Chemical Physics published new progress about Density functional theory, B3LYP. 71195-85-2 belongs to class esters-buliding-blocks, and the molecular formula is C9H3F5O2, Electric Literature of 71195-85-2.
Referemce:
Ester – Wikipedia,
Ester – an overview | ScienceDirect Topics