Liquid–Polymer Contact Electrification: Modeling the Dependence of Surface Charges and ξ-Potential on pH and Added-Salt Concentration

• DOI: 10.1021/acs.langmuir.2c00813
• Publication Date: 2022-07-14T16:02:44Z
• Authors: Mariana D. Sosa; Norma B. D’Accorso; M. Luz Martínez R...; R. Martín Negri
• Keywords: Charge density; Surface charge; Contact electrification

Here, a mathematical model is presented, which accounts for the dependence of surface electrical charge density (σ) on pH and concentration added salts (Cs), generated when water drop rolls or slides hydrophobic polymer, process known as liquid-polymer contact electrification (LPCE). The same was successfully applied to fit isotherms ξ-potential function pH, reported in literature by other authors water-poly(tetrafluoroethylene) (PTFE) interfaces. Hence, σ ξ described using concept: acid-base equilibria at water-polymer interface. Equilibrium constants were estimated fitting experimental isotherms. results are consistent with number 10-100 sites/μm2. predicts increase |σ| |ξ| range 2-10 existence zero-charge point pHzcp ≅ 3 PTFE (independent Cs). Excellent fits obtained Ka/Kb ∼ 9 × 107, where Ka Kb respective acid base equilibrium constants. On hand, observed decrease Cs fixed quantitatively introducing an activity factor associated quenching salt ions polymer-water interface, constant Kq. Additionally, extreme I > (1/Kq) (I: ionic strength), agreement reports.