Versatile lignin-reinforced natural rubber latex adhesives: Integrating strength, environmental resilience, and controlled biodegradability

To address the unsustainability and environmental-health risks associated with conventional petroleum-based adhesives, we report a sustainable route to high-performance adhesives via ammonium persulfate (APS)-initiated grafting of alkali lignin (AL), sodium lignosulfonate (SLS), and enzymatic hydrolysis lignin (EHL) onto natural rubber latex (NRL). Grafted formulations show a >50 % increase in lap shear strength, a ≈4 % rise in glass transition temperature (T g , from −62.4 °C to −59.8 °C), and stable adhesion under 70 % relative humidity. Soil burial tests reveal controlled biodegradation (20.6 % vs. 29.2 % mass loss for AL-grafted NRL and pure NRL). Enhanced antioxidant and mold-resistance further underscore lignin's dual reinforcing and stabilizing roles. This versatile platform delivers tunable performance and predictable end-of-life behavior for green packaging and biomedical adhesives.