Superspreading and Drying of Trisiloxane-Laden Quantum Dot Nanofluids on Hydrophobic Surfaces

Abstract

Nanofluids hold promise for a wide range of areas of industry. However, understanding of wetting behavior and deposition formation in course of drying and spreading of nanofluids, particularly containing surfactants, is still poor. In this paper, the evaporation dynamics of quantum dot-based nanofluids and evaporation-driven self-assembly in nanocolloidal suspensions on hexamethyldisilazane-, polystyrene-, and polypropylene-coated hydrophobic surfaces have been studied experimentally. Moreover, for the very first time, we make a step to understanding of wetting dynamics of superspreader surfactant-laden nanofluids. It was revealed that drying of surfactant-free quantum dot nanofluids in contrast to pure liquids undergoes not three but four evaporation modes including last additional pinning mode when contact angle decreases whilst triple contact line is pinned by the nanocrystals. In contrast to previous studies, it was found out that addition of nanoparticles to aqueous surfactant solutions leads to deterioration of spreading rate and to formation of double coffee ring. For all surfaces examined, superspreading in presence and absence of quantum dot nanoparticles takes place. Despite the formation of coffee rings on all substrates, they have different morphology. Particularly, the knot-like structures are incorporated into the ring on hexamethyldisilazane-and polystyrene-coated surfaces.

“Umbrella” Structure Trisiloxane Surfactant: Synthesis and Application for Reverse Flotation of Phosphorite Ore in Phosphate Fertilizer Production

“…In addition, the recovery of quartz with 5 × 10 –5 mol/L AATS was 41.5% and higher than that of DDA at the same dosage. According to previous studies, compared with conventional surfactants containing a similar and single alkyl hydrophobic group, trisiloxane surfactants distributed on the water surface in an “umbrella” structure can weaken the surface tension and enhance the surface hydrophobicity. − Low surface tension may facilitate the production of steady weeny air bubbles during the flotation course. − Moreover, the trisiloxane group occupied a larger volume than the −C 12 H 25 group, and this increased the collision probability between the quartz and bubbles. Furthermore, trisiloxane surfactants have a stronger ability to prevent the bubble from coalescing and achieved froth stability than conventional surfactants. , …”

Achieving High Efficacy and Low Safety Risk by Balancing Pesticide Deposition on Leaves and Fruits of Chinese Wolfberry (Lycium barbarum L.)

“…The retention behavior of the solution on the surface is affected not only by the surface characteristics but also by the characteristics of the solution. The contact angle and adhesion tension of the solution determine that the retention of the solution on the surface and are dependent on the surface tension . In the process of pesticide application, after the spraying mode and surface are determined, the properties of the pesticide diluent can be regulated by adding adjuvant, which can affect the retention of pesticide on the crop surface and meet the specific needs of humans. , People usually hope that more pesticides can be deposited on the target surface, which will help to improve the control efficacy of pesticides on disease.…”

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

“…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.…”