Visible light‐induced thiol‐ene reaction: A new strategy to prepare Α, ω‐dithiol and Α, ω‐divinyl telechelic polythiolether oligomers. Issue 6 (26th September 2015)

• Record Type: Journal Article
• Authors: Ma, Wenchao; Chen, Dong; Liu, Lianying; Ma, Yuhong; Wang, Li; Zhao, Changwen; Yang, Wantai
• Is Part Of: Journal of polymer science. Volume 54:Issue 6(2016)
• Page Start: 740
• Page End: 749
• Publication Date: 2015-09-26
• Subjects: addition polymerization -- photopolymerization -- photoredox catalyst -- telechelics -- thiol‐ene chemistry; 547
• DOI: 10.1002/pola.27906
• Languages: English
• ISSNs: 0887-624X

Abstract

ABSTRACT: A new strategy is developed to prepare both α, ω‐dithiol and α, ω‐divinyl linear telechelic polythiolether oligomers by visible light induced thiol‐ene chemistry in the presence of a fac ‐Ir(ppy)3 photoredox catalyst. Polythiolether oligomers of well‐defined end groups and controlled molecular weights have been successfully synthesized at varying monomer molar ratios of 1, 4‐benzenedimethanethiol (BDMT) to diethylene glycol divinyl ether (DEGVE). 1 H NMR and MALDI‐TOF MS analyses demonstrate that as‐prepared polythiolethers possess high end‐group fidelity, which is further supported by the successful polyaddition of polythiolethers bearing α, ω‐dithiol and α, ω‐divinyl groups. For example, with the α, ω‐dithiol‐ ( M n = 1900 g mol −1, PDI = 1.25) and α, ω‐divinyl‐terminated ( M n = 2000 g mol −1, PDI = 1.29) polythiolethers as macromonomers, the molecular weight of resulting polythiolether is up to 7700 g mol −1 with PDI as 1.67. The reactivity of the terminal thiol group is further confirmed by the addition reaction with N ‐(1‐pyrenyl)maleimide. UV‐vis spectra and fluorescene measurements suggest that fac ‐Ir(ppy)3 undergo a redox quenching process reacted with BDMT to generate thiyl free radicals. With these results, the mechanism of the thiol‐ene reaction catalyzed by photoredox catalyst is proposed. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem.2016, 54, 740–749 Abstract : Both α, ω‐dithiol‐ and α, ω‐divinyl‐terminated linear polythiolether oligomers are obtained by visible light induced thiol‐ene chemistry in the presence of a fac ‐Ir(ppy)3 photoredox catalyst. Thereafter, a well‐defined polymer ( M n =7700 g mol −1, PDI=1.67) is obtained by polyaddition of α, ω‐dithiol‐ ( M n =1900 g mol −1, PDI=1.25) and α, ω‐divinyl‐terminated ( M n =2000 g mol −1, PDI=1.29) oligomers. The results demonstrate that as‐prepared α, ω‐dithiol and α, ω‐divinyl linear telechelic polythiolether oligomers possess high end‐group fidelity.