Self-healing bio-based membranes for eco-efficient fertilizers: Abrasion resistance, controlled release and soil biodegradability

Bio-based membrane shells with excellent abrasion resistance, high elasticity and self-healing ability hold significant potential for enhancing the quality and utilization of membrane-coated bio-based controlled-release fertilizers (BCRFs). In this study, we developed a simple and practical method for preparing novel bio-based membrane shells that exhibited superior elasticity (>200% water absorption and expansion without rupture), reduced porosity (−13.07%), and enhanced tensile and tensile strength (reaching 1003.8% and 15.704 MPa). The resulting self-healing bio-based controlled-release fertilizer (SBCRF) showed higher compressive strength (withstanding 90 N pressure), extended nitrogen release longevity (+40%) and excellent wear resistance (with overlapped nutrient release curves before and after abrasion). Crucially, the strategic cross-linking oxime-carbamate bonds and hydrogen bonds into the polyurethane network structure conferred SBCRF with self-healing function. Molecular dynamics simulations further confirmed the reversible reorganization of broken chemical bonds with restored energy, facilitating repair of the damaged region. These attributes collectively improved the accuracy and stability of nutrient release from SBCRF, while enabling soil biodegradation of the shells (with 43.77% mass loss after 180 days). Field trials in small cabbage demonstrated an 8.6% increase in nitrogen utilization efficiency compared to conventional BCRFs. This study provides a theoretical and technological foundation for the development of stable and efficient BCRFs, advancing the goals of green and intelligent agriculture.