Directly observed Au-S bond breakage due to swelling of the anchored polyelectrolyte.

A weak polyelectrolyte coating, carboxylated poly(oligo(ethylene glycol)methacrylate-co-2-hydroxyethylmethacrylate), was prepared via surface initiated polymerization (SIP) from initiators immobilized to gold surface through the Au-S bonds. When dry thickness increased up to 75 nm, this polyelectrolyte coating was pulled off the Au substrate by simply exposing to phosphate buffer saline (PBS, pH = 7.4, [Na(+)] = 150 mM). This covalent bond breaking (CBB) behavior was monitored in situ using a quartz crystal microbalance (QCM) and CBB was associated with the swelling of the anchored polyelectrolyte chains.