Titanium/polymer sheets designed for biomedical applications

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The project deals with the design of new Ti/polymer(P)/Ti and P/Ti/P sheets for biomedical applications, controlling their interface and adjusting their mechanical properties and shaping behaviour. Elaboration, process development, analysis of the properties, and their forming limits will be performed in synergy between three partners with the goals:1. Developing strategies to design P/Ti interfaces in sandwich sheets (SMs) to employ surface-confined, resin free compatible polymer layers as adhesives for a strong bond between P and Ti for final shaping without delamination. “Grafting from” and “Grafting to” methods will be used, allowing a larger choice of monomers. “Grafting from” to produce Ti/P/Ti SMs with modulated properties in polymer by designing the glass transition temperature of the selected polymer. A polymerization initiator will be grafted at NaOH modified-Ti surface via a phosphonate anchor. Linear polymer chains of various molar masses, as homopolymers or copolymers types will be grown from the initiator using a controlled radical polymerization process. The monomers used will be as methyl methacrylate (MMA), n-butyl methacrylate (nBMA) and methyl acrylate (MA). A mixture of monomers will be used for the synthesis of random copolymers..“Grafting to” for bioactive thick polymer layers on Ti of homo and copolymers of sodium 4-styrenesulfonate (NaSS) and MA. A readily accessible anchor incorporating both an anchoring group (catechol), capable of forming a robust, stable monolayer, and a clickable function allowing the modular and efficient post-functionalization of the Ti surface will be used. In parallel, polymers or copolymers bearing thiol end groups will be attached using thiolene click reaction onto the monolayer. Linear polymer chains of various molar masses, as homo-polymers or co-polymers types will be synthetized by a controlled radical polymerization to give thiol-ends. In order to obtain thiol end polymers or copolymers, addition-fragmentation transfer polymerization will be chosen. The monomers used will be NaSS and/or MMA and a mixture of monomers to synthetize statistical copolymers.2. Fabricating Ti/P/Ti or P/Ti/P SMs; SMs will be processed at IMET by bonding modified Ti sheets to commercially or in laboratory made polymer foils of defined thicknesses (e.g. PMMA or PMMA-co-PBMA foils or PMMA-co-PNaSS foil). The feasibility of the “Grafting from” method was stated in a preceding project.3. Tailoring the mechanical properties close to the bones’ ones. Mechanical and shaping properties will be studied and controlled by modulating the molecular and structural parameters of the polymers or the ratio of the layer thicknesses.4. Stability and cytocompatibility of the SMs will be conducted.The advantages of these systems usable for cranioplasty and mandible surgery will be lightweight SMs with mechanical properties designable in the range of bones’ ones and improved thermal and acoustic properties compared to Ti.