Synthesis and Characterization of a New Thioxanthone-based Polyester-derived Macrophotoinitiator

Özçelik Kazancıoğlu E., Arsu N.

7th European Symposium of Photopolymer Science, İstanbul, Turkey, 19 - 22 September 2022, pp.66

  • Publication Type: Conference Paper / Summary Text
  • City: İstanbul
  • Country: Turkey
  • Page Numbers: pp.66
  • Yıldız Technical University Affiliated: Yes


Photoinitiators, which can be defined as compounds that initiate the polymerization reaction by absorbing UV light and forming free radicals, are the key components in UV-curing formulations. According to the process of free radical formation, photoinitiators can be classified as type I and type II [1]. Some photoproducts of photoinitiators may exhibit a variety of physical and chemical properties that reduce the efficiency of photoinitiation and the performance of the cured product. Due to the instability of radicals, photoproducts of both type I and type II photoinitiators are susceptible to rearrangement, coupling, oxidation, and decomposition. Some of these byproducts may be colorful or fragrant, with a propensity to move. Another risk is photoinitiator residues that remain unreacted in the UV curing process [2, 3]. In addition, tertiary amine migration in photoinitiator/amine binary systems is dangerous for health because the amine is both toxic and mutagenic [4]. Macrophotoinitiators are defined as macromolecular systems with pendant or in-chain chromophores that, upon light absorption, form active species capable of initiating the polymerization and crosslinking of mono- and multi-functional monomers and oligomers. In general, the presence of the polymer improves formulation compatibility and reduces migration to the film surface. Thus, it contributes to the production of low-odor and non-toxic coatings [5, 6]. In this study, thioxanthone catechol-O,O-diacetic acid (TX-Ct), which has one-component type II photoinitiating property, was synthesized as stated in the literature [7], and TX-polyester with photoactive properties was obtained as a result of polymerization reaction with ethylene glycol and p-toluene sulfonic acid. Characterized TX-polyester was used as macrophotoinitiator in photoinitiated free radical polymerization of methyl methacrylate and the characterization of the obtained polymer was performed spectrophotometrically and chromatographically.

This work was supported by Research Fund of Yildiz Technical University under project number: FDK-2022-4876.


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[6] Akat, H., Gacal, B., Karaca Balta, D., Arsu, N., Yagci, Y., (2010). “Poly(ethylene glycol)-thioxanthone prepared by Diels– Alder click chemistry as one-component polymeric photoinitiator for aqueous free-radical polymerization”, Journal of Polymer Science: Part A: Polymer Chemistry, 48, 2109–2114.

[7] Karasu, F., Karaca Balta, D., Liska, R., Arsu, N. (2010). “Photoinitiated polymerization of b-cyclodextrin/methyl methacrylate host/guest complex in the presence of water soluble photoinitiator, thioxanthone-catechol-O,O-diacetic acid”, J Incl Phenom Macrocycl Chem., 68, 147-153.

Keywords: photoactive, macrophotoinitiator, thioxanthone, polyester