Mechanism and Conformation of Polyelectrolyte Binding to Surface

Polyelectrolytes are widely used as antiscalants due to their effective chelation of Ca²⁺ ions and their ability to delay the growth of CaCO₃ surfaces. In this antiscaling process, the binding between polyelectrolytes and the CaCO₃ surface is critical for determining the effectiveness of surface passivation. Experiments have shown that polyacrylic acid (PAA) copolymers, including those with acetate or alcohol monomers, exhibit better antiscaling properties than the PAA homopolymer. However, the underlying binding mechanism remains unclear. To address this, we perform molecular dynamics simulations investigating how PAA copolymers with the same charge density interact with the CaCO₃ surface. We employ OneOPES, an enhanced sampling method, to explore the extensive conformational spaces of the polyelectrolyte and calculate the potential of mean force between the copolymers and the surface. We then analyze the binding modes of each monomer and the conformations of the adsorbed copolymers, aiming to elucidate the monomer-specific effects on affinity and propose design principles for polyelectrolytes.