A greener route for smart PNIPAm microgel synthesis using a bio-based synthesis-solvent

• A novel sustainable route was developed using bio-based 2-MeTHF for PNIPAm microgel synthesis with desirable properties. • The monomer conversion and rate of polymerization in 2-MeTHF was nearly equivalent to that in conventional solvents like THF. • PNIPAm synthesis in 2-MeTHF has a much lower carbon footprint (97% reduction in carbon emissions) than synthesis in conventional solvents. A novel route for poly(N-isopropylacrylamide) (PNIPAm) microgel synthesis using the bio-based solvent 2-Methyltetrahydrofuran (2-MeTHF) is described. Functional and chemical characterization of the PNIPAm microgels synthesized in 2-MeTHF indicates that they are equivalent to microgels synthesized using conventional organic solvents. The volume phase transition temperature was 31.7 °C, the glass transition temperature was observed at 157 °C, and the swelling ratio was 3.7 (dry mass basis). XRD and FT-IR spectroscopic analysis confirmed the successful synthesis of crosslinked PNIPAm microgels. The role of 2-MeTHF as a chain transfer agent in the polymerization can be explained by hydrogen abstraction from the C2 atom position of 2-MeTHF during the chain transfer step of free radical polymerization. An eco-sustainability analysis of the synthesis of PNIPAm microgels in bio-based 2-MeTHF indicates that this route has a much lower carbon footprint than synthesis in conventional solvents, thus providing a more sustainable route for the synthesis of smart microgels for environmental and biomedical applications.