Surface-immobilised anti-fouling block-copolymers: synthesis and characterization

Poly(ethylene glycol) (PEG)-based polymers have been widely employed in anti-fouling coating applications due to their robust bio-relevant properties including water solubility and biocompatibility. However, limited by its poor adhesion towards surfaces, demands an addition modification strategies. Mussel adhesive proteins (MAPs) are potential models for adhesive polymers, which exhibits underwater adhesion towards dissimilar materials under environmentally challenging conditions. Most often experimentally simple, but structurally complex poly(dopamine) has been used as an analogues of MAPs for metal chelation, cross-linking and surface binding purposes. Inspired by MAPs, we have developed catechol-bearing copolymers for surface adhesion of stainless steel. This study aims at developing novel catechol-bearing, PEG-based block-copolymers by reversible addition-fragmentation chain transfer (RAFT) polymerization technique. PEGA used as macro-RAFT to prepare acetonide-protected catechol as second block. Deprotection of acetonide groups under acidic conditions produced functional block-copolymer with free catechols as pendant moieties. The self-assembling nature of amphiphilic block-copolymers was studied by 1H-NMR, DLS and TEM. Surface functionalization and anti-fouling experiments were performed in real time using quartz crystal microbalance coupled with dissipation (QCM-D). The copolymer upon oxidation yields reactive quinones, which can be exploited to cross-link with chitosan (also, polymers with free –NH2 and –SH groups), thereby producing nano(macro)gels. Benefited from inherent anti-microbial and anti-oxidative properties of chitosan and catechol-respectively, could result in potential materials for water purification systems, food packaging and medical devices.