Chang, J. J., Ong, N. W. X., Ong, D. Y., Owh, C., Lin, Q., Oh, X. Y., Zhao, W., Boo, Y. J., Sim, B., Cheong, A., Goh, R., & Loh, X. J. (2026). Universal Base-Catalyzed Aza-Michael Addition: A General Platform for Transforming Polyurethanes into High-Performance Injectable Thermogels. Journal of the American Chemical Society. https://doi.org/10.1021/jacs.6c06443
Abstract:
Postpolymerization functionalization (PPF) of polyurethanes remains a persistent challenge, typically requiring the preinstallation of specialized reactive handles during initial synthesis. This limitation restricts the upcycling and advanced modification of existing, industrial-scale polyurethane materials. Herein, we report a universal and scalable strategy to transform “off-the-shelf” polyurethanes by leveraging the ubiquitous carbamate moiety (RO–C(═O)–NH–R) as a direct chemical handle for aza-Michael addition. Catalyzed by the phosphazene superbase P2-tBu, this method achieves high degrees of functionalization (up to 99%) across a diverse substrate scope, including various acrylates and vinylphosphonate. Using this platform, we engineered a new class of comb-like poly(alkylene oxide) thermogels whose branched topology imparts transformative viscoelastic properties. These materials exhibit a 5-fold decrease in viscosity under shear, significantly outperforming the industry standard Pluronic F-127, while requiring 3-fold lower extrusion forces through 27-gauge needles, ensuring superior injectability. Furthermore, the branched architecture enables exceptionally sustained therapeutic release with a cumulative drug release of only 59% over 324 h compared to the rapid 52-h depletion of Pluronic F-127. This work establishes a general, handle-free pathway for the precision engineering of functional polyurethanes, bridging the gap between commodity plastics and high-performance biomaterials.
License type:
Publisher Copyright
Funding Info:
This research / project is supported by the National Research Foundation - NRF Investigatorship
Grant Reference no. : NRFI07-2021-0003
This research / project is supported by the A*STAR - Industry Alignment Fund – Pre-Positioning
Grant Reference no. : H20c6a0033