Environmentally Friendly Synthesis of Poly(hydroxyurethane) Vitrimer Microspheres and Their Potential Application in Moisture-Enabled Electric Generation

Vitrimers, a unique polymer with dynamic covalent bond networks, have gained considerable attention in the past decade due to their potential to promote sustainable development in polymer materials. Since their first report in 2011, a series of efficient reactions have been explored for vitrimer synthesis. However, implementation of these reactions to generate vitrimers with specific structures, such as microspheres, foam, and aerogels, for targeted applications has received limited attention. Herein, we report a facile and efficient method for synthesizing poly(hydroxyurethane) (PHU) vitrimer microspheres using a synergistic combination of liquid-liquid microphase separation and polymerization-induced microphase separation. The approach employs multifunctional amines and cyclic carbonates as reactants, instead of highly toxic isocyanates, and does not require additional catalysts, surfactants, and stabilizers. Furthermore, a green and recyclable solvent, gamma-valerolactone, serves as the reaction medium. More importantly, we demonstrate that PHU microspheres can be directly synthesized in cellulose-based fabrics, such as nonwoven cotton tissue and woven cotton cloth, resulting in sponge-like PHU@fabric hybrid materials with a promising application in moisture-enabled electric generation. This study demonstrates a fast and efficient way to access vitrimer microspheres and simultaneously opens an application of vitrimer materials in the field of green energy harvesting.