Complementary Thiourethane-Boronate Chemistry for the Covalent Integration of Hyaluronic Acid into Dynamic...

The covalent integration of hydrophilic biomacromolecules into hydrophobic synthetic polymer networks remains a key challenge, primarily arising from significant interfacial incompatibility and phase separation. Here, we introduce a complementary dual-dynamic covalent approach that synergistically combines thiourethane chemistry with boronic ester cross-linking to seamlessly incorporate hyaluronic acid (HA) into polyurethane networks. Thiourethane linkages, formed via thiol-isocyanate click chemistry, serve as the network backbone and undergo associative trans-thiocarbamoylation, while boronic ester bonds between pendant phenylboronic acid groups and the cis-diols inherent to HA provide dynamic bio-synthetic interlinks. This complementary design creates a hierarchical network with confirmed covalent incorporation, as demonstrated by a 20% reduction in spin-spin relaxation time and a 1.8-fold increase in storage modulus. The resulting network offers strong mechanical performance (25.6 MPa tensile strength, 530% elongation), efficient self-healing (91% recovery), and a broad operating temperature range (-49 to 168 °C). This chemically unified matrix further enables the stable inclusion of liquid metal for strain sensing (gauge factor up to 160). This work establishes a general pathway that leverages complementary dynamic chemistries to address interfacial mismatch in biosynthetic hybrid materials, paving the way for thermally stable and multifunctional biointegrated systems.