Patrick Choquet

The design of new, biomimetic biomaterials is of great strategic interest and is converging for many applications, including in implantology. This study explores a novel approach to improving dental implants. Although endosseous TA6V alloy dental implants are widely used in oral implantology, this material presents significant challenges, notably the prevalence of peri-implantitis. Therefore, in this study, we investigate a new advance in the design of hybrid medical devices. This involves the design of a Ca-SZ coating deposited by PVD on a TA6V substrate. This approach aims to overcome the inherent limitations of each of these materials, namely TA6V’s susceptibility to peri-implantitis on the one hand and zirconia’s excessively high Young’s modulus compared with bone on the other, while benefiting from their respective advantages, such as the ductility of TA6V and the excellent biocompatibility of zirconia, offering relevant prospects for the design of high-performance implantable medical devices. This study integrates characterisation techniques, focusing on the structural and elemental analysis of the Ca-SZ coating by XRD and TEM. The results suggest that this coating combines a tetragonal structure, a uniform morphology with no apparent defects, a clean interface highlighting good adhesion, and a homogeneous composition of calcium, predisposing it to optimal biocompatibility. All of these findings make this innovative coating a particularly suitable candidate for application in dental implantology.

Hydrophobic coatings based on dodecyl acrylate (DOCA) and perfluorodecyl acrylate (PFDA) have been generated via “postdischarge” atmospheric pressure plasma deposition. These coatings exhibit a water contact angle (WCA) of around 125° but are accompanied by poor mechanical strength. To improve this property, two different types of chemical crosslinkers, that is, hexanediol methacrylate (HDMA) and hexanediol diacrylate (HDA), are incorporated into the precursor mixture. After plasma polymerization, both coatings with crosslinkers admixture show different wettability behavior. The addition of HDMA reduces the WCA while increasing the mechanical strength, while the addition of HDA retains the initial WCA magnitude while also increasing the mechanical strength. These changes are related to variations of the surface free energy (SFE) and topography of the plasma coatings.

Strontium titanate (STO) is a well-known oxide used in a wide variety of applications due to its excellent stability and optoelectronic properties. However, its integration in photoelectrocatalytic devices is limited by the lack of fast and scalable methods to produce robust films at a low temperature and atmospheric pressure. Herein, we report an atmospheric pressure plasma-enhanced chemical vapor deposition (AP-PECVD) approach for the synthesis of STO crystalline films and their applications for photoelectrochemical solar energy conversion. The film crystallinity, which plays a determinant role in the photoelectrochemical performance, was linked to the selected strontium precursor and injection method. Through thermal stability studies of the precursors [Sr(dpm), Sr(ipo), Sr(acac), and Ti(ipo)] and analysis of the solution droplet size, it was demonstrated that the closer thermal decomposition behavior and superior miscibility of the Sr(dpm) and Ti(ipo) precursors led to more homogeneous and crystalline films with the highest photoelectrochemical performance (16.5 μA cm^–2 at 1.23 V vs RHE under 100 mW cm^–2), which can be further improved by a factor of 3.4 using thermal annealing at 500 °C. Evidence of the impact of a strontium precursor on the properties of STO films is provided through thermogravimetric analysis, X-ray diffraction, energy-dispersive system, UV–vis, X-ray photoelectron spectroscopy, HIM-SIMS, and photoelectrochemical analysis.

TiO ₂ thin films of various thicknesses have been deposited on silicon at low-temperature by PECVD operating in continuous mode ( T < 130 °C) and pulsed mode ( T < 80 °C) using oxygen/titanium isopropoxide low-pressure inductively coupled plasma. The study of the crystallinity and microstructure of the films by atomic force microscopy, scanning electron microscopy and x-ray diffraction allowed showing that the roughness and amount of anatase are closely related to the film thickness. The coalescence of large polycrystalline columns emerging from an assembly of thin columns was found to happen at a critical thickness, at about 150 nm in the continuous mode and 250 nm in the pulsed mode. Real time in situ spectroscopic ellipsometry study allowed to monitor the growth and to determine this critical thickness for both plasma modes. The change of morphology type to large columnar structure is associated with an important increase in the photocatalytic activity. The determination of this coalescence thickness by ellipsometry may provide an interesting method to evaluate the impact of process parameters on TiO ₂ thin films characteristics.

In this study, an efficient methodology, allowing the controlled co‐immobilization of two complementary biomolecules, is reported for the production of multifunctional antibacterial surfaces. To promote long‐lasting covalent immobilization, metallic surfaces are first coated with a quinone‐bearing poly(methacrylate)‐based thin film by combining an atmospheric pressure liquid‐assisted plasma polymerization and a controlled sodium periodate‐induced catechol oxidation steps. The influence of the oxidation step on the film morphology and chemistry is investigated using an analytical multitool approach involving atomic force microscopy, ultraviolet, infrared, and X‐ray photoelectron spectroscopy techniques. Quartz crystal microbalance with dissipation monitoring (QCM‐D) analyses allow the rapid determination of the optimal biomolecule immobilization conditions in terms of kinetics of grafting and biomolecule solution concentrations. In vitro functional assays combined with QCM‐D analyses demonstrate promising, dual biologically active coated surfaces.

The growth of thermoresponsive layers with the atmospheric pressure plasma-initiated chemical vapor deposition (AP-PiCVD) process is reported for the first time. N-vinyl caprolactam (NVCL) was successfully homopolymerized and copolymerized with ethylene glycol dimethacrylate (EGDMA), yielding water-soluble and water-stable thermoresponsive thin films, respectively. Strong chemical retention and high thermoresponsivity were achieved, highlighting the ability of AP-PiCVD to grow functional conventional homopolymers and copolymers.