Layer-by-layer self-assembly of polyelectrolyte multilayers on cross-section surfaces of multilayer polymer films: A step toward nano-patterning flexible substrates

Polyelectrolyte multilayers (PEMs) of poly(acrylic acid) (PAA)/poly(allylamine hydrochloride) (PAH) were successfully deposited onto novel nano-striped surfaces, which were generated using the cross-section surfaces of multilayer polymer films made from poly(ethylene-co-acrylic acid) (EAA) and linear low-density polyethylene (LLDPE). The procedure of PEM patterning consisted of three steps: nano-striped pattern formation, PEM deposition, and chemical crosslinking. It was observed that the PEMs were selectively deposited on the EAA layers and linked through covalent bonds, but those on LLDPE layers were washed off during sonication in water and methanol. In addition, the reactive moieties introduced by PEMs were successfully used to bond covalently with other important molecules, such as amine-terminated fluorescein. This kind of nano-striped surface with alternating wettability could serve as a template for many applications, including biomedical, separations, and electronics.