A pH-responsive polyelectrolyte multilayer film with tunable interfacial properties

We report a facile and versatile approach to fabricate polyelectrolyte multilayer (PEM) films with a chemically modifiable outer surface. A PEM film was prepared by layer-by-layer assembly of poly (2-aminoethyl methacrylate) (PAMA) and polymethacrylic acid (PMAA), terminated with a partially tert-butyloxycarbonyl (Boc)-protected random copolymer (PAMA-co-PBocAMA) as the final layer.

The obtained PEM film was then cross-linked and the free amino groups in the PEM film were quenched using EDC/NHS chemistry. The outer layer of the film was then treated via a deprotection reaction, affording free amino groups selectively located at the film surface. As a proof of concept study, these functional groups were used to modify the film surface with two model hydrophilic and hydrophobic compounds, which tuned the wettability of the PEM.