Biomimetic Superhydrophobic Biobased Polyurethane-Coated Fertilizer with Atmosphere "Outerwear".

The development of efficient biobased controlled-release fertilizers has captured much research attention because of the environmental concerns and food scarcity problems. In this work, a biomimetic superhydrophobic biobased polyurethane-coated fertilizer (SBPF) was successfully fabricated by increasing surface roughness and reducing surface energy of polyurethane (PU) coating. The green PU coating was synthesized from low-cost, biodegradable, and renewable cottonseed oil. The nutrient release longevity of SBPF revealed 2-fold enhancement compared with the normal biobased PU-coated fertilizer (BPF). The significant improvement of nutrient release characteristics can be attributed to the atmosphere "outerwear" which ensured the nonwetting contact of water with superhydrophobic surfaces in gas state instead of in liquid state. The new concept introduced in this study can inform the development of the next generation of biobased controlled release fertilizers.