Grafting PEG Fragments on Phynox Substrates Modified with 11-Phosphoundecanoic Acid

Abstract

Phynox, a cobalt-chromium alloy, exhibits interesting mechanical properties, making it a valuable material for several applications. However, applications as a biomaterial often require specific surface properties that can be imparted with suitable surface functionalizations. The aim of this work is to functionalize the Phynox surfaces with 11-phosphoundecanoic acid monolayers, creating a platform for a large variety of postgrafting chemical reactions, e.g., with alcohols and amines, to modify and control the surface properties. In the first part, we assess the interaction between the two terminal moieties of the 11-phosphoundecanoic acid and the Phynox surface by studying the grafting of n-dodecylphosphonic acid and n-dodecanoic acid. To illustrate the potential of the 11-phosphoundecanoic acid monolayer, we report on our first attempts to postgraft small poly͑ethylene glycol͒ ͑PEG͒ fragments by the Steglich esterification reaction between the carboxylic end of the grafted 11-phosphoundecanoic acid molecules and the alcohol function of PEG fragments.Phynox ͑also known as Elgiloy or Conichrome͒ is an austenitic cobalt-chromium alloy ͑Association française de normalisation designation: K13C20N16Fe15D07͒. In addition to a very high yield strength, Phynox offers a range of interesting physical and chemical properties such as a remarkable resistance to corrosion, a good fatigue strength, its ability to be used in a wide range of temperatures ͑from liquid helium to about 500°C͒, and a high passivity in contact with human tissues. All these properties make Phynox a suitable alloy for applications where a high mechanical performance is required under severely corrosive service conditions such as springs for watch motors, flexible couplings, electrical and electronic apparatuses, aeronautical and aerospace equipment, automotive injection systems, naval equipment, weaponry, surgical implants, and medical instruments, and pacemaker electrodes.In combination with its remarkable bulk properties, several Phynox applications, in particular the biomedical ones, require specific surface properties that can be imparted with suitable surface functionalizations of the Phynox protective oxide layer. The tendency of organophosphonic acids to form monolayers on metal oxide surfaces 1-4 and their important resistance to homocondensation and hydrolysis 5,6 make them particularly interesting candidates for such oxidized surface functionalizations. The grafting of phosphonic acid compounds has been studied on several metal oxides such as aluminum, 7-25 titanium, 26-43 titanium alloys, 44,45 silicon, 46-49 iron, 50 zinc, 51,52 nickel, 53 silver, 54 tantalum, 55-57 and stainless steel. 58 In the frame of biomedical applications, grafting of organophosphonic acids on SS316L 59 and Nitinol, 60 two alloys commonly used for stents/endovascular prothesis, has already been studied, but such work has not been done on Phynox.The aim of the present work is to functionalize the Phynox surfaces with 11-phosphoundecanoic acid monolayers. The resulting ...

Polyelectrolyte Multilayer Deposition on Nickel Modified with Self-Assembled Monolayers of Organophosphonic Acids for Biomaterials: Electrochemical and Spectroscopic Evaluation

“…PC 11 COOH monolayers bring carboxylic functional groups at the surface of the nickel substrates and are therefore expected to promote the electrostatic adhesion of the first polycation layer. As expected, its ability to bind surface via both terminal functions and therefore the existing competition between these two functions , leads to very poorly covering monolayers (only about 6%). PC 11 COOMe was expected to lead to the formation of more close-packed and protective SAMs because of the absence of this competition.…”

“…49,56 However, because of its ability to bind surface via both terminal functions and therefore because of the existing competition between these two functions, this molecule has been reported to form complex systems of simply/doubly bound molecules. 57,58 Accordingly, PC 11 COOMe has been used in order to avoid this competition and to obtain more close-packed and protective SAMs. Negative charges have been formed on the surface of these PC 11 COOMe monolayers by hydrolysis of the ester terminal functions.…”

“…The grafting of bifunctional phosphonic and carboxylic acid molecules is often used for metal oxide surface functionalization. For instance, Kruszewski and Gawalt recently reported on the use of such bifunctional molecule SAMs for surface-initiated polymerization. , However, because of its ability to bind surface via both terminal functions and therefore because of the existing competition between these two functions, this molecule has been reported to form complex systems of simply/doubly bound molecules. , Accordingly, PC 11 COOMe has been used in order to avoid this competition and to obtain more close-packed and protective SAMs. Negative charges have been formed on the surface of these PC 11 COOMe monolayers by hydrolysis of the ester terminal functions.…”

1-Dodecanethiol Self-Assembled Monolayers on Cobalt

“…Recently, the interest for cobalt alloys has grown. Several studies showed the importance of surface property control. ,− In this context, the interest of using self-assembled monolayers (SAMs) is well-known, in particular for the corrosion inhibition of oxidizable metals. Nowadays, numerous works have been carried out on copper − and nickel , because of the economic interest of these metals.…”

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)

“…However, silane derivatives grafted on metal oxide surfaces are comparatively more sensitive to hydrolysis , in physiological pH conditions than their organophosphonic acid analogues. Due to their remarkable resistance to homocondensation , and ability to bind strongly on a large variety of metal oxide surfaces (including the most commonly used alloys in the biomaterials field, that is, SS316L, Nitinol, − and Phynox ,, ) organophosphonic acids are candidates of choice as anchoring groups for the elaboration of corrosion resistant SI-ATRP platforms. Babu et al have reported the synthesis of 2-bromo-2-methyl-propionic acid 2-phosphonooxy-ethyl ester, and its grafting on magnetite nanoparticles of polymer brushes (PMMA and PS) by ATRP. , Kim et al have formed ferrocene functional polymer brushes on ITO using 6-(2-bromo-2-methylpropanoyloxo)­hexylphosphonic acid as SI-ATRP initiator .…”