Enhancing Droplet Spreading on a Hydrophobic Plant Surface by Surfactant/Cellulose Nanocrystal Complexes

A surfactant is an efficient and common additive used to enhance the spreading of droplets on hydrophobic surfaces. However, a high surfactant concentration is required to achieve the desired performance, resulting in environmental pollution and increased costs. Additionally, the pesticide loading capacity of surfactants at low concentrations (below their critical micelle concentrations) is a concern. Thus, in this study, we developed a strategy to enhance pesticide loading and droplet deposition by mixing small amounts of sodium dodecyl sulfate (SDS) (0.1 wt %) and cationically modified cellulose nanocrystals (PCNC). The reduced surface tension, increased viscosity and adhesion, and electrostatic and hydrogen interactions resulted in a low retraction velocity, excellent spreading, and resistance to air turbulence. The improved loading content was facilitated by the hydrophobic domains of PCNC and SDS micelles.