(332c) Reversible Adhesion between Surfaces with Oppositely Charged Weak Polyelectrolyte Brushes

In contrast to strong polyelectrolytes, weak polyelectrolytes present electrostatic charges in accordance with the solution pH and the local chemical environment. The pH-responsive behavior is advantageous for applications in smart systems to achieve specific functions such as reversible adhesion. However, a quantitative description of such phenomena poses challenges due to the intricate interplay among polymer configuration, interfacial behavior, and solution conditions. Inspired by experimental findings, we propose a theoretical investigation to elucidate the mechanisms governing the adhesion between surfaces grafted with oppositely charged weak polyelectrolyte brushes. Various parameters of the opposing brushes control the adhesion capability including their grafting density, chain length, and chemical identity. The reversibility in the adhesion can be controlled by tuning the pH, salt type, and salt concentration of the surrounding solution. In this work, we utilize 3D Ising density functional theory and the single-chain-in-mean-field algorithm (sc-iDFT). Our theoretical framework overcomes limitations of existing approaches by explicitly accounting for the intramolecular correlations that dictate the charge and conformation of the single-chain polymer while also including the intermolecular correlations that dictate the response of the brush toits local environment.