Development of smart regenerative surface is a highly challenging but important task for many scientific and industrial applications. In this work, we synthesized three polyzwitterionic brushes of poly (3-(1-(4-vinylbenzyl)-1H-imidazol-3-ium-3-yl) propane-1-sulfonate) (polyVBIPS), poly (N-(4-vinylbenzyl)-N,N-dialkylamine) (polySVBA), and poly (4-(2-Sulfoethyl)-1-(4-vinyl-benzyl) pyridinium betain) (polySVBP) using the surface-initiated atom transfer radical polymerization. Three VBIPS, SVBA, and SVBP monomers used to form polymer brushes all contain the same anionic moiety, but the different cationic moieties. The surface hydration, lubrication, and antifouling properties were systematically characterized by atomic force microscopy (AFM), contact angle, in-situ ellipsometer, surface plasmon resonance (SPR), and bacterial adsorption assay. Collective experimental data show that when responding to the changes of salt concentrations and salt types, all zwitterionic brushes exhibited unique switching abilities between surface dry/wettability, friction/lubrication, and fouling/antifouling properties. Among them, polySVBA outperformed others in terms of these salt-responsive properties, including ultralow protein and bacterial adsorption (&lt;5 ng/cm<sup>2</sup>) and superior lubrication (μ ~10<sup>-3</sup>). The salt-responsive behaviors of these zwitterionic brushes can be interpreted by the “anti-polyelectrolyte effect”, i.e. zwitterionic brushes adopt a collapsed chain conformation at low ionic strengths to achieve high surface adhesion and high frication, but an extended chain conformation at high ionic strength to realize antifouling and lubrication properties, both of which are linked to surface hydration. More importantly, unlike many surfaces with “one-time switching” capability for surface regeneration, our zwitterionic polymer brushes can be regenerated to retain their salt-induced switching properties for multiple cycles. This work provides new promising material systems for the fabrication of smart surfaces with biocompatible, reliable, regenerative properties.

Zwitterionic polymer brushes for salt-responsive polymer structure-surface activity relationship

253rd National Meeting (2017)

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