Abstract
The popularity of using the photopolymerization reactions in various areas of science and technique is constantly gaining importance. Light-induced photopolymerization is the basic process for the production of various polymeric materials. The key role in the polymerization reaction is the photoinitiator. The huge demand for radical and cationic initiators results from the dynamic development of the medical sector, and the optoelectronic, paints, coatings, varnishes and adhesives industries. For this reason, we dealt with the subject of designing new, highly-efficient radical photoinitiators. This paper describes novel photoinitiating systems operating in UV-Vis light for radical polymerization of acrylates. The proposed photoinitiators are composed of squaraine (SQ) as a light absorber and various diphenyliodonium (Iod) salts as co-initiators. The kinetic parameters of radical polymerization of trimethylolpropane triacrylate (TMPTA), such as the degree of double bonds conversion (C%), the rate of photopolymerization (Rp), as well as the photoinitiation index (Ip) were calculated. It was found that 2-aminobenzothiazole derivatives in the presence of iodonium salts effectively initiated the polymerization of TMPTA. The rates of polymerization were at about 2 × 10−2 s−1 and the degree of conversion of acrylate groups from 10% to 36% were observed. The values of the photoinitiating indexes for the most optimal initiator concentration, i.e., 5 × 10−3 M were in the range from 1 × 10−3 s−2 even to above 9 × 10−3 s−2. The photoinitiating efficiency of new radical initiators depends on the concentration and chemical structure of used photoinitiator. The role of squaraine-based photoinitiating systems as effective dyeing photoinitiators for radical polymerization is highlighted in this article.
Highlights
A large number of polymer materials is produced by photopolymerization [1]
Of dye as sensitizer and co-initiator in the form of iodonium salt, what was proposed by Zhang and co-workers in 2019 [49] we examined the kinetics of the radical polymerization of trimethylolpropane (TMPTA) using novel photoinitiators on photoinitiators based on triacrylate
Characteristics of Photoinitiators mentioned above, in for thisthe article we proposed new bimolecular photoinitiators wereAs used as a determinants evaluation of the photoinitiation efficiency of new composed of squaraine dye as a photosensitizer and iodonium salt in the role effective of a cosquaraine-based photoinitiators
Summary
A large number of polymer materials is produced by photopolymerization [1]. Photochemically induced polymerization is defined as a process in which reactive species (radicals or ions) formed from light-activated molecules, called photoinitiators (PI), initiate a series of chemical reactions and as a result transform liquid monomers into cross-linked polymer structures. The photopolymerization is considered as one of the most widespread, modern and rapidly developing technologies used in the chemical industry [2,3,4]. Photoinitiated polymerization reactions show a huge potential in the simple and fast synthesis of polymeric materials with specified features. In comparison with the conventional curing techniques, the interest towards photochemically initiated polymerization is constantly gaining importance [5]. The increasing popularity of photopolymerization is related to numerous unique
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