Synthesis of Sulfur/Selenium-containing Polyester with Recyclability and Controllable Hydrophilicity and Glass Transition Temperature

We present a ring-opening polymerization of bridged cyclic lactone utilizing alcohol as the initiator and organic base as the catalyst. Bridged γ -butyrolactone monomers (PhSGBL and PhSeGBL) were synthesized efficiently from commercially available 3-cyclohexene-1-carboxylic acid. Due to the ring strain of the bridged structure, ring-opening polymerization of this type of γ -butyrolactone derivative was successfully carried out under mild conditions, e.g. , using ethylene glycol as the initiator and a commercial catalyst [1,5,7-triazabicyclo [4.4.0 dec-5-ene (TBD)] as the catalyst at 30 °C. The obtained polymer could be degraded to its monomer for recycling in the presence of ZnCl 2 as a catalyst. PhSGBL and PhSeGBL could also be copolymerized with ε -caprolactone to tune the glass transition temperature. Additionally, the hydrophilicity of the obtained sulfur-containing polymers could be adjusted by selectively oxidizing the thioether side group to sulfone/sulfoxide, which offered a way to tune the hydrophilicity of polyester. On the other hand, the obtained selenium-containing compound could be degraded in the presence of m -CPBA (3-chloroperbenzoic acid), which offered potential application in sustained drug release.