Polymer brush on surface with tunable hydrophilicity using SAM formation of zwitterionic 4-vinylpyridine-based polymer

Zwitterionic 4-vinylpyridine-based polymers were immobilized on different surfaces by a self-assembled monolayer (SAM) formation technique for better durability and reliability. Atomic force microscopic studies revealed dense polymeric brushes with a high degree of smoothness. A large variation in water contact angle was observed when the surface was treated with buffers of different pH, indicating a tunable hydrophilicity of the polymeric brush. The contact angle variation was observed under both acidic and basic media, possibly due to the presence of both quaternary ammonium groups and carboxylic acid functionality. Interestingly, a time-dependent contact angle variation under different pH was observed when the polymer was directly coated on the leather surface