Rapid polythioether synthesis and thioether network formation using thiol-yne chemistry of electron-deficient alkynes

Abstract

The preparation of polythioethers has gained importance again after the development of click chemistry reactions. The thiol-X reactions, i.e., thiol-ene reactions based on free radical mechanism facilitated by light or heat, and thiol-Michael and thiol-epoxy reactions, which are the main synthetic pathways for the synthesis of polymers (linear, hyperbranched (HB), and network) with thioether linkages and meet most of the features of click reactions strategy, have currently been revisited. For a while, our group has focused on synthesizing linear, HB, and network polythioethers based on electron-deficient alkyne-containing precursors. We have shown that electron-deficient alkyne-containing monomers and polymers offer a suitable platform for thiol-Michael (i.e., thiol-yne) click reactions to yield linear, HB, and network structures rapidly under ambient conditions. The central structure in these polythioether syntheses is electron-deficient alkyne bonds of acetylenedicarboxylates, which are then reacted with dithiols in chloroform through an organobase 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) at ambient temperatures. Moreover, acetylenedicarboxylates are functionalized using copper-free azide-alkyne cycloaddition reaction followed by reacting with multifunctional allyl and SH derivatives through thiol-ene photopolymerization resulting in polymeric networks with thioether linkages. This feature article highlights our contribution to the synthesis of linear, HB, and network polythioether based on various electron-deficient alkyne precursors.

GRAPHICAL ABSTRACT

Keywords:

• Polythioether
• organocatalyst
• thiol-Michael
• acetylenedicarboxylates
• click chemistry
• network formation
• thiol-yne

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Ufuk Saim Gunay

Ufuk Saim Gunay obtained his undergraduate degree from Istanbul Technical University (ITU), Istanbul, Turkey. He received his Ph.D. from ITU in 2017, in the area of click chemistry. He visited Strasbourg University for six months during his Ph.D. studies. He became an assistant professor in 2019 at ITU. He has authored 33 articles in international journals. His research interests are click reactions and polymer synthesis.

Umit Tunca

Umit Tunca He has been a professor at the Chemistry Department of Istanbul Technical University, Turkey, since 1998. He has published over 150 papers and 3 book chapters. His research interests are mainly living radical polymerizations and click reactions. His awards include Monbusho (Japan) (1987), Alexander von Humboldt (Germany) (1990) research fellowships, and TUBITAK (The Scientific and Technological Research Council of Turkey) Young Investigator (1997).

Hakan Durmaz

Hakan Durmaz completed his Ph.D. in 2010 at the Chemistry Department of the Istanbul Technical University (ITU), Turkey. He continued his post-doctoral studies at the University of Michigan (USA) between 2012 and 2014. He became an associate professor in 2015 and a full professor in 2020 at ITU. He has received many research awards from various institutions in Turkey. He has published more than100 peer-reviewed articles. His research interests include polymer synthesis, modification, and applications from various aspects.