Nanolayered Films of Spin-Coated, Covalently-Assembled Poly(Vinylpyrrolidone)- and Poly(Vinylpyridine)-Based Copolymers

Sequential deposition of polymer layers of very diverse characteristics has been applied to produce nanoassemblies of well-controlled thickness and physico-chemical properties. While conventional layer-by-layer approaches are based on the sequential deposition of distinct, mutually interacting materials, nanoassemblies formed by a single, unique polymer are challenged by the need of chemically interacting units to ensure layer-to-layer binding. Here, pyrrolidone and pyridine-containing polymers are mixed with the bifunctional crosslinker 1,6-dibromohexane and sequentially spin-coated as single, neutral polymers. The incorporation of the crosslinker within each deposited layer enables stepwise covalent bond formation while the nanofilm is being assembled. N-alkylation of amine groups by the crosslinker's alkyl halides during thermal annealing post-layer deposition ensures both intra and interlayer crosslinking with a single formulation. Thickness, growth profile, surface roughness, and wettability of the covalently bound nanoassemblies are evaluated together with their interaction with Staphylococcus aureus and HeLa cancer cells. The antibacterial and non-adhesive properties of a set of nanofilms are investigated and discussed in light of the physico-chemical characteristics of the films.