Sequential SI-ATRP in μL-scale for surface nanoengineering: A new concept for designing polyelectrolyte nanolayers formed by complex architecture polymers

The article presents a step-by-step protocol, designed on the basis of principles of green chemistry, for the synthesis of polymer brushes with complex structure via surface-initiated atom transfer radical polymerization (SI-ATRP) approach. The selection of anionic (poly(acrylic acid), PAA) and cationic (poly(2-(dimethylamino)ethyl methacrylate, PDMAEMA) macromolecular chains enabled the formation of ampholytic polymer coating on silicon (Si) substrates. Scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) analyses confirmed changes in the structure of the synthesized nanolayer at each step of the surface modification. Finally, the synthesis protocol was rescaled presenting an extremely economically and environmentally beneficial procedure for the synthesis of Si wafers grafted with brushes composed of poly(2-hydroxyethyl methacrylate) (PHEMA) core and PDMAEMA and PAA as block polymer branches (Si-g-PHEMA-g-(PDMAEMA-b-PAA)) with application of microliter volumes of reactants.