Hydrogen-bonded lignin-acrylic copolymer/WPU composites with Integrated UV shielding, antioxidancy and degradability

To address the poor degradability and stability of traditional polyurethanes, and the low dispersibility hindering high-value use of industrial lignin, in this study, lignin extracted from rice straw and acrylic acid (AA) were employed as raw materials to synthesize a lignin-acrylic acid copolymer (LAC) with a high lignin content and a disordered network structure via a hydrothermal crosslinking reaction using potassium persulfate (KPS) as the initiator under alkaline conditions. Through physical blending with waterborne polyurethane (WPU), LAC/WPU composite films (LACW) were fabricated, establishing an interpenetrating hydrogen-bonded network. This structure confers multifunctional enhancements: for the representative 40 % LACW composite, this structure confers multifunctional enhancements: the tensile strength increases by ~43 % (0.47 → 0.67 MPa) versus pure WPU, the radical scavenging capacity shows a dramatic increase of over 350 % (16 % → 74 %, DPPH assay), and it offers near-total UV shielding (>99 % blocking efficiency across 280-400 nm). By converting agricultural waste into high-performance additives, this work establishes a scalable paradigm for lignin valorization, simultaneously mitigating microplastic pollution and advancing circular materials design with demonstrable economic and ecological benefits.