Double-modified biopolymer-coatings based on recyclable poplar-catkin: Efficient performance, controlled-release mechanism and rice application

Abstract

Reasonably utilizing the renewable poplar-catkin resources (>20 million ha worldwide) to develop the biopolymer to replace non-renewable petrochemical coatings has attracted increasing environmental interest. However, the terrible water repellency, the poor compactness, and the accompanying terrible controlled release quality of the poplar-catkin-derived biopolymer coating cannot satisfy the long-term requirements of the crops. In this work, the water-repellent and compact biopolymer-coatings based on the recyclable poplar-catkin were developed with a nontoxic modifying agent, simple technology, and low-cost raw materials. The enhanced water repellency and the improved compactness of the WCPUs coating can be confirmed by the three-dimensional computerized tomography (3.46 to 0.50 %). Therefore, the nutrient controlled-release longevities of the WCPUs were dramatically improved and the nutrient controlled-release prediction models were established. The increased elasticity (716 to 77.3 MPa) of the WCPUs coating was also important to enhance the controlled-release performance. The controlled-release mechanism was also clarified: The air columns inside of the tiny micropores prevent the liquid water from entering the coating and only allow the water molecules through the coating in vapor form. The significantly improved rice yield (57.23 %) showed the reliable application effect of the WCPUs. This work provides an efficient strategy to improve the recognition degree from the farmers and promotes the development of low-cost and eco-friendly bio-derived controlled-release fertilizers.