Development Of Photoinitiators Research Articles

Photobleachable coumarin-thioester derivatives with low cytotoxicity as visible-light photoinitiators for free radical and cationic photopolymerization

The development of photoinitiators is suffering from deep color, low solubility, and biotoxicity caused by the introduction of large-conjugated structures, also the complex synthetic procedures constrain the application of photoinitiators. To overcome this issue, nine kinds of coumarin thioester photoinitiators (CTEs) have been delicately designed and synthesized through a simple, metal-free two-step reaction. CTEs with excellent light absorption properties in the visible light range can be used not only as a type I photoinitiator but also as a type II photoinitiator, and sensitizer in the cationic photoinitiating system. CTEs effectively initiate the photopolymerization of tripropylene glycol diacrylate (TPGDA) under the irradiation of 405 nm LED, and the double bond conversions are similar to or better than those of commercial photoinitiators. Also, the cationic photopolymerization of bisphenol A diglycidyl ether (BADGE) is successfully initiated by CTEs/IOD systems. Notably, the epoxy group conversion initiated by 6O-CTE/IOD reaches 72.1 %, surpassing that of the commercial photoinitiating system. The photoinitiating mechanism of CTEs is proposed and supported by theoretical calculations. Furthermore, the bond cleavage abilities of CS bonds endow CTEs with photobleaching properties. The colorless cured film initiated by 6O-CTE was obtained under only 15 s irradiation, indicating their application prospects of CTEs in colorless photopolymerization. More importantly, the cytotoxicity of CTEs is much lower than that of commercial photoinitiator TPO. This work provides new insight into the design of biocompatible photoinitiators with a photobleaching property for LED photopolymerization.

Alkyl chain engineered photo-initiators for the fabrication of biobutanol permselective pervaporation membranes

Despite much progress in the development of photo-initiators (PIs) for many advanced applications, their high migration and weak thermal stability are still challenging. Especially, it easily results in an incomplete curing and sacrificial separation performance in the use of polymeric membranes. PI 2-hydroxy-2-methylpropiophenone (1173) has been most frequently used in photocuring owing to its high reactivity and universal applicability. Herein, we reported a series of alkyl chain engineered PI 1173 with different chain lengths for fabricating polydimethylsiloxane (PDMS) membranes. The dodecyl isocyanate functionalized PI 1173 displayed a lower migration ratio of 1.42% from the PDMS matrix compared with 2.99% for PI 1173. Its degradation temperature was also improved where the weight loss was only 10% as the temperature was raised to 241.1 °C. Importantly, the fabricated PDMS membranes initiated by alkyl chain engineered PIs showed an excellent n-butanol permselective pervaporation (PV) with separation factor of 38–54 and total flux of 818–1396 g m−2 h−1 when feeding 1.5 wt% n-butanol aqueous solution at 60 °C. It provides a general method for fabricating high-quality separation membranes.

Development of Photoinitiators in Electronic Applications.

An overview of the photoinitiators for use in electronic applications is given, including both, commercially available products as well as semi-commercial or developmental products. Areas to be covered are photoinitiators for PCB manufacturing and flat-panel displays production process and photoacid generatiors for use in semiconductor resists.