2-(Benzylthio)ethyl Glycidyl Ether: A Gateway to Redox-Responsive Polyethers

This work presents the design and synthesis of a functional epoxide monomer, 2-(benzylthio)ethyl glycidyl ether (BTGE), serving as a versatile building block for the development of redox-responsive polyethers. It details the successful synthesis of a series of poly(2-(benzylthio)ethyl glycidyl ether) (PBTGE) homopolymers and ABA-type triblock copolymers (i.e., PBTGE-b-PEO-b-PBTGE), achieved through controlled anionic ring-opening polymerization of the BTGE using a poly(ethylene oxide) (PEO) macroinitiator. Comprehensive characterization of the synthesized monomers and polymers was performed employing various analytical techniques, such as 1H- and 13C NMR, GPC, FT-IR spectroscopy, and MALDI-ToF mass spectrometry. These polymers demonstrate unique redox-responsive behavior, characterized by an oxidation-induced transition from hydrophobic to hydrophilic states and a reductive deprotection to generate free thiol groups. Furthermore, the PBTGE-b-PEO-b-PBTGE triblock copolymers have been utilized to form physically cross-linked hydrogels through the strong hydrophobic interactions of the end blocks. Notably, these hydrogels undergo a gel-to-sol transition under oxidative conditions, as evidenced by rheological analysis. This study highlights the potential of the BTGE monomer as a versatile building block for the development of advanced materials with dual redox-responsive functionalities.