Temporal variations of surface roughness and thickness of polymer-coated quartz sand

In this work, the changes in surface roughness and thickness of particles have been investigated after coating with polymers that result in hydrophobicity after a given time period. The study fundamentally investigates the evolution of these surface properties from the instant the particles are coated. Six chemical agents have been used on near-spherical glass beads and the changes in surface profiles monitored. Surface roughness was quantified using the power spectral density method and the surface thickness of the coatings was determined by a new technique which involved calculating the change in the representative radius of asperity. Results showed that the coating process altered the surface roughness and thickness of particles irrespective of chemicals used. The time-dependency of the coating process is illustrated and it was observed that fluctuations in both surface roughness and thickness lessened after a time period of 30 min. Depending on the chemical agent used, either an overall roughening or softening was recorded at 60 min and the values of surface thickness showed increases between 71 and 256 nm. By analyzing the evolution of surface roughness and thickness at the particle level following coating, this study demonstrated the intricate link between surface properties and chemistry in inducing functional properties on particles. Graphical Abstract