Promoting efficacy and environmental safety of photosensitive agrochemical stabilizer via lignin/surfactant coacervates

Photolysis and migration seriously reduce utilization efficiency of photosensitive agrochemicals, which leads to vast losses of ecological and economic benefits. Here we develop a novel method for preparing water-based coacervate as a stabilizer for photosensitive agrochemicals by utilizing single-chain/gemini surfactants and sodium lignosulfonate (SL), a renewable and ubiquitous biopolymer abandoned by pulping industry that presents excellent intrinsic ultraviolet (UV) resistance. Coacervates contain intricate nanoscale networks and abundant bound water, resulting in highly effective encapsulation of hydrophilic and hydrophobic solutes, and entanglement with the micro- and nanostructures of a superhydrophobic surface without sacrificing its ability to resist UV degradation. These coacervates display a high encapsulation efficiency for photosensitive abscisic acid (ABA) up to 90%, and resist UV degradation for 70 times longer than that in pure water, and act as an optimal substrate for the deposition of encapsulated agrochemicals on superhydrophobic leaves after high-speed impact. As a result, the drought resistance of wheat seedlings is significantly improved after spraying ABA protected by SL-coacervates, compared with free ABA, demonstrating that agrochemicals sequestered in coacervates effectively alleviate photolysis and migration loss. Thus, using a lignin-based coacervate can be used to potentially promote productive and sustainable agriculture, by serving as a highly efficient and environmental-friendly stabilizer for photosensitive agrochemicals used in pesticide applications.