Electrografting of mixed organophosphonic monolayers for SI-ATRP of 2-methacryloyloxyethyl phosphorylcholine

Abstract: Nitinol (NiTi), one of the most important alloys for biomedical applications, is still hampered by its surface nickel inclusions, making it sensitive to pitting corrosion and leading therefore to the release of potentially carcinogenic Ni²⁺ ions. In this work, we assess the impact of the combination of electrografted mixed self-assembled monolayers (SAMs) on NiTi followed by a polymer coating formed by surface-initiated atom transfer radical polymerization (SI-ATRP). The molecular ratio of 11-(2-bromoisobutyrate)-undecyl-1-phosphonic acid (BUPA) to 11-decylphosphonic acid (C₁₀P) on the electroassisted elaboration of the (BUPA/C₁₀P)-NiTi-SAMs has been optimized. A small amount of BUPA (20%) appears to be the most promising condition, as it provides an efficient corrosion resistance and promotes the SI-ATRP of 2-methacryloyloxyethyl methacrylate (MPC). This confers to the surface hydrophilic properties and corrosion resistance close to those NiTi-SAMs when long polymerization times are used (≥ 6 h). Graphical abstract: [Figure not available: see fulltext.].