Bastien Barthélémy

Induction heating Vs conventional heating for the hydrothermal treatment of nitinol and its subsequent 2-(Methacryloyloxy)ethyl 2-(trimethylammonio)ethyl phosphate coating by surface-initiated atom transfer radical polymerization

Nitinol is an alloy of great interest in general and especially in the biomedical field where many researches are aimed to improve both its corrosion resistance and its biocompatibility. In this work, we report on the advantage of an induction heating treatment in pure water compared to a conventional hydrothermal procedure. Both treatments lead to a hydroxylation of the surface, a decrease of the nickel amount in the outer part of the oxide layer, and a drastically decreased corrosion current density. However, the amount of surface hydroxyl groups is higher in the case of the induction heating treatment, which in turn leads to a denser grafting of atom transfer radical polymerization initiators and ultimately to a thicker 2-(methacryloyloxy)ethyl 2-(trimethylammonio)ethyl phosphate (MPC) polymer layer than in the case of conventional heating treatments. X-ray photoelectron spectroscopy (XPS), static contact angle, and polarization curves measurements as well as scanning electron microscopy (SEM) have been used to characterize the obtained modified surfaces.

Induction heating for surface triggering styrene polymerization on titanium modified with ATRP initiator

Titanium and its alloys present high interests for technological applications due to their high corrosion resistance, mechanical properties and biocompatibility. In combination with these remarkable characteristics, some Ti applications require specific surface properties that can be imparted with suitable surface functionalizations of the TiO(2) oxide layer. The present work aims to study the surface-initiated ATR polymerization of styrene on titanium substrates, using grafted 11-(2-bromoisobutyrate)-undecyl-1-phosphonic acid as initiator and to compare the impact of two different heating ways on the efficiency of this polymerization: induction vs. conventional heating. The ability of the initiator to bind titanium substrates and act as an initiator for ATRP of styrene is investigated: both heating conditions led to the polymerization of styrene on modified titanium substrates. However, induction heating appeared to be much more efficient than conventional heating, leading to the formation of a thicker, much denser polystyrene layer than conventional heating after only 1h of polymerization.

Synergistic effect on corrosion resistance of Phynox substrates grafted with surface-initiated ATRP (co)polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) and 2-hydroxyethyl methacrylate (HEMA).

Phynox is of high interest for biomedical applications due to its biocompatibility and corrosion resistance. However, some Phynox applications require specific surface properties. These can be imparted with suitable surface functionalizations of its oxide layer. The present work investigates the surface-initiated atom transfer radical polymerization (ATRP) of 2-methacryloyoxyethyl phosphorylcholine (MPC), 2-hydroxyethyl methacrylate (HEMA), and ATRP copolymerization of (HEMA-co-MPC) (block and statistic copolymerization with different molar ratios) on grafted Phynox substrates modified with 11-(2-bromoisobutyrate)-undecyl-1-phosphonic acid (BUPA) as initiator. It is found that ATRP (co)polymerization of these monomers is feasible and forms hydrophilic layers, while improving the corrosion resistance of the system.