Regulating Droplet Impact and Wetting Behaviors on Hydrophobic Weed Leaves by a Double-Chain Cationic Surfactant

Abstract

The addition of a surfactant is a constructive strategy to enhance the deposition of pesticides on plant leaves in agriculture. However, currently used surfactants normally require to be used at high concentrations, and most of them are anionic or nonionic. In this work, we found that didecyldimethylammonium bromide (DDAB), a double-chain cationic surfactant, can not only inhibit droplets from receding and rebounding but also promote sufficient spreading on paraffin and Chenopodium album L. leaf surfaces at an ultralow concentration (0.05%), in comparison with widely reported sodium dodecyl sulfate (SDS) and bis(2ethylhexyl)sulfosuccinate (AOT). This phenomenon is attributed to the fast adsorption kinetics of DDAB from the bulk to the newly created interface (mere 100 ms), decreasing the surface tension significantly. Field experiments further prove that the addition of DDAB can significantly improve the control efficiency of herbicides. Our findings provide a simple and effective way for improving the droplet deposition on hydrophobic plant surfaces, which may lead to economic and environmental benefits in the future.

Regulating Droplet Wetting and Pinning Behaviors on Pathogen-Modified Hydrophobic Surfaces: Strategies and Working Mechanisms

“…The elongation distance of Pyra droplets on cucumber powdery mildew leaves in the No.1 growth stage was relatively long. The weight on the metal ring decreases directly from the original 0 value to a negative value, which means that the droplets quickly wet the surface after touching the cucumber leaf and then quickly separate from the metal ring . For the No.0 growth stage of cucumber leaves, the Pyra + AEO-3 and Pyra + Silwet618 droplets had the best adhesion, and most of the droplets remained on the cucumber leaves, followed by the Pyra + AEO-4 and Pyra + AEO-5 droplets (Figure A).…”

“…The wetting and spreading behavior of a droplet is usually characterized by the dynamics of its microscopic contact line . The presence of special structures on some hydrophobic surfaces inhibits the wetting and spreading of droplets. , In cases where it is not possible to manipulate the inherent properties of a surface, we can change the properties of a liquid to adjust wetting and spreading. To date, many scientific studies have focused on regulating the wetting behavior of water droplets on hydrophobic surfaces via surfactants. , However, some major problems in practical agricultural applications still exist: (1) much is unknown about the wetting and spreading behaviors of pesticides that contain surfactants; (2) the interaction between pesticide droplets and leaf surfaces modified by pathogenic bacteria has been reported rarely; and (3) the process by which droplets wet and spread on plant leaves has not been explored.…”

“…The presence of special structures on some hydrophobic surfaces inhibits the wetting and spreading of droplets. , In cases where it is not possible to manipulate the inherent properties of a surface, we can change the properties of a liquid to adjust wetting and spreading. To date, many scientific studies have focused on regulating the wetting behavior of water droplets on hydrophobic surfaces via surfactants. , However, some major problems in practical agricultural applications still exist: (1) much is unknown about the wetting and spreading behaviors of pesticides that contain surfactants; (2) the interaction between pesticide droplets and leaf surfaces modified by pathogenic bacteria has been reported rarely; and (3) the process by which droplets wet and spread on plant leaves has not been explored. Therefore, further understanding these problems holds great significance for practical applications of pesticide droplets.…”

“…Surfactants can not only increase the wetting ability of pesticides and improve the prevention and control of pests and diseases , but also improve the ability of pesticides to permeate surfaces to control weed . Surfactants can spontaneously adsorb on various interfaces, which leads to the enhancement of wetting and adsorption properties of solutions .…”

Amyloid‐Like Protein Aggregation Toward Pesticide Reduction

“…The enhancement of pesticide drop retention is co‐contributed from two aspects, including 1) the droplet deposition and 2) pesticide adhesion to resist rainfall erosion. For example, the use of synthetic polymers, [ 9 , 18 , 22 ] surfactants, [ 19 , 20 , 21 , 22 , 69 , 70 , 71 ] charged droplets, [ 23 , 24 , 25 , 26 ] TiO 2 hydrophilic nanoparticles, [ 72 ] Folate/Zinc supramolecular hydrogels, [ 73 ] or nanofibers assembled from natural glycyrrhizic acid [ 74 ] could enhance 1) on the hydrophobic or superhydrophobic surfaces, while the use of nanocarriers such as high energy electron beam (HEEB)‐modified attapulgite aggregates, [ 27 , 28 ] plant ash, [ 75 ] polydopamine nanoparticles, [ 29 ] or phosphorylated zein (P‐zein) [ 30 ] enhances 2). Although trimeric surfactant [ 31 ] and castor oil‐based cationic/anionic polyurethane dispersions (WPU) [ 32 ] were used to increase droplet deposition while immobilizing pesticides have been reported, they are not ideal systems for pesticides retention due to their complex synthesis processes and low fixation efficiency.…”