Polyelectrolyte Monolayers at the Mica/Air Interface: Mechanically Induced Rearrangements and Monolayer Annealing

We have carried out a series of experiments on the mobility of a polyelectrolyte monolayer (thickness: 0.7 nm) in a nitrogen atmosphere with the surface force apparatus. If two polyelectrolyte monolayer covered surfaces come into contact, we observe a polyelectrolyte meniscus surrounding the contact area. After separation of the surfaces, a polyelectrolyte ring tracing the rim of the former contact area can be found. The monolayer anneals within minutes. (To observe the isolated monolayer, the optics of the surface forces apparatus bad to be further developed.) From wetting and photobleaching experiments with fluorescent-labeled monolayers, we deduce that the annealing is a monolayer flux driven by the change in surface energy. We find that the relative humidity (rh) mainly influences the annealing time if rh ≤80%. However, at rh 100%, not a polyelectrolyte but a water meniscus is observed. Polyelectrolyte bilayers can be deformed plastically, yet they do not anneal