Water–Polymer\nSlide Electrification in Polyethylene\nFilms Coated with Amphiphilic Compounds and Its Connection to Surface\nProperties Dependent on Water–Polymer Interactions

Slide electrification experiments were performed on low-density\npolyethylene films (<b>PE</b>) and <b>PE</b> sprayed with\nfive amphiphilic compounds, including antistatic and slip additives.\nDrops of aqueous solutions were delivered on the films and after sliding\nspontaneously acquired a net electrical charge (<b>Q</b><sub><b>drop</b></sub>), which is dependent on the pH and ionic\nstrength. The slide electrification was detected in pristine <b>PE</b> films and those with five additives. An acid–base\nequilibrium model, based on the adsorption of hydroxides and protons\non surface sites, accounted for the dependence of <b>Q</b><sub><b>drop</b></sub> on pH, allowing recovery of the acid–base\nequilibrium constants and the density of adsorption sites. The model\nwas modified to account for ionic strength effects through activity\nfactors. The surface conductivity, wettability, and friction coefficients\nwere strongly modified by the additives. However, the observed trends\nare different from those observed in slide electrification, which\nbetter correlated with zeta potential determinations. This suggests\nthat the interaction mechanisms among surface water, the considered\nadditives, and the polymer, which are involved in slide electrification\nand the generation of zeta potential, are different from those associated\nwith other surface processes involving surface water. Although additives\nare required for changing surface resistivity, friction coefficients,\nand wettability, the generation of sliding electrical charges in polyethylene\nis a spontaneous and highly effective process. For one specific additive,\na simultaneous decrease in friction coefficients, zeta potential,\nand <b>Q</b><sub><b>drop</b></sub> was observed, assigned\nto the blockade of hydroxide adsorption sites and water repulsion\nby the compound.