Key points are not available for this paper at this time.
This study investigates the influence of hydrophobicity on particle adsorption by examining the behavior of hydrophobized silica particles at air-water interfaces. Langmuir-Blodgett (LB) trough studies of butanol (‘SiO-butane’) and hexanol (‘SiO-hexane’) esterified particles provided contrasting behavior. The SiO-butane particles formed weaker particle layers that underwent partial collapse with compression, leading to formations significantly below hexagonal close-packed estimates. In contrast, the SiO-hexane particles exhibited improved monolayer behavior and longer-range stability. Droplet surface tensions demonstrated that the hydrophobic particles significantly altered the dynamic tension during adsorption, when methyl isobutyl carbinol (MIBC) was added as a co-surfactant. Short-term modeling elucidated the role of diffusion and energy barriers on adsorption dynamics, with SiO-hexane having reduced diffusion coefficients with respect to SiO-butane and unmodified particles. Despite this reduced diffusion, long-term modeling allowed calculation of adsorption coefficients ( k a ), which for SiO-hexane particles were ∼200 × greater than for unmodified particles at low 0.1 wt% particle concentrations and over 1000 × greater at 2 wt%. Overall, the results provide quantitative insights into the profound influence of hydrophobicity on particle adsorption, particularly in crowded surface environments. Importantly, a diffusion-only mechanism is inadequate to explain adsorption dynamics for these larger colloids and the gravity-driven contribution must be considered in early-stage kinetics. • Adsorption of esterified silica examined by Langmuir trough and surface tension. • High hydrophobicity enhances monolayer stability near layer collapse. • Diffusion and adsorption rate modeled with short and long-time approximations. • Greater hydrophobicity boosts adsorption rates 200–1000 × unmodified particles. • Adsorption mechanism is attributed to a mixed diffusion-kinetic process.
Chen et al. (Sat,) studied this question.