Nanoscale patterning through self-assembly of hydrophilic block copolymers with one chain end constrained to surface

Poly(oligo(ethylene glycol) methacrylate) (POEGMA)-block-poly(2-(methacryloyloxy) ethyl trimethylammonium chloride) (PMETAC) brushes were synthesized on silicon wafer surfaces by a surface-initiated atom transfer radical polymerization (ATRP) method. Salt-triggered collapse of the polyelectrolyte in solution was employed to induce phase segregations between the two hydrophilic blocks and thus to develop nanoscale patterns. The smallest feature size was about 10 nm and was tunable on the nanoscale. Various patterns including spherical aggregates, wormlike aggregates, and line patterns were obtained through adjusting the upper block layer thickness. These nanopatterns could switch between the different morphologies through the treatment of selective solvents. The adsorption behavior of fibrinogen on these patterns was also studied by ellipsometry, water contact angle measurement, AFM and radio labelling method. The results showed that these nanopatterns possess the ability to pattern proteins.