Organophosphonic acids as viable linkers for the covalent attachment of polyelectrolyte brushes on silica and mica surfaces

Abstract

We report the first successful preparation of polyelectrolyte brushes using an ATRP initiator that was covalently grafted to silica and mica substrates via an organophosphonic acid. Covalent attachment of the initiator to silica and mica and the subsequent synthesis of polyacrylic acid (PAA) and poly(sulfopropyl methacrylic acid) brushes by water mediated-ATRP were confirmed by ATR-FTIR, ellipsometry, AFM, and contact angle measurements. The initiator–substrate bond was robust and could resist a large range of pH in the absence of salt. Interactions between PAA brushes anchored to mica via the organophosphonic acid initiator were investigated using a surface forces apparatus. The results confirmed the robustness of the initiator–mica bond as the brushes could resist shearing and compression under relatively high applied loads.