I made my first steps in the wonderful sol-gel world around 25 years ago during my chemical engineer studies. I worked on sol-gel synthesis of butyl tin oxo-cluster (“BuSn12 “) and SnO2 -based antistatic coatings (Synthesis and characterization of crystalline tin oxide nanoparticles – Journal of Materials Chemistry (RSC Publishing) for the windshields of aircraft. I was mentored by Dr François Ribot at the Laboratoire de la Chimie de la Matière Condensée de Paris (LCMCP), Sorbonne University. He was the first to give me the passion for scientific research and to introducing me to the subtleties of sol-gel chemistry. I was so enthusiastic that I pursued a PhD on silane grafting onto the surface of silica nanoparticles in aqueous-based medium with Rhodia Recherches (today Solvay) and the LCMCP (Covalent grafting of organoalkoxysilanes on silica surfaces in water-rich medium as evidenced by 29Si NMR | SpringerLink). These functionalized particles were developed for use as mechanical reinforcement to increase pneumatic durability and to reduce environmental footprint. During this period, Francois Ribot, Florence Babonneau and Christian Bonhomme formed a fabulous trio of advisors who guided me through the winding paths of sol-gel synthesis and to determine if the chemical link of the grafting is covalent or not. And over all the scientific work performed, they taught me that in the “sol-gel spirit”, colorful vocabulary is usual. I finished my PhD by describing the grafting of silanes onto particles by “lianas” or “coli-flowers” depending on the synthesis conditions employed. More seriously, they taught me the need to be rigorous and to explore in-depth the relationships between synthesis parameters and physiochemical characterisation on multiple length scales, and to correlate these with the resulting macroscopic properties. This multiscale approach of understanding, which is widely used today, was not largely widespread at this period, particularly in industry. This is still now my way of working by “changing altitude” and points of view to find the best way to proceed.
Following the completion of my doctoral studies, I continued exploring functional nanoparticles as a post-doctoral researcher, firstly with Alcatel, and secondly at the LI2C (today PHENIX) Sorbonne University. I worked on solgel hydrothermal syntheses, with a particular focus on two systems. The first of these involved doping boehmite and antimony oxide with Er3+ and their integration into optic fibers for telecom application (Espacenet – Bibliographic data). The second explored the synthesis of suitable-sized maghemite (Fe2 O4 ) magnetic nanoparticles for further surface functionalization for cancer treatment by hyperthermia HOME – SuperBranche EN, which required the synthesis of particles larger than 10 nm that had not been previously achieved at that time (Hydrothermal synthesis of large maghemite nanoparticles: influence of the pH on the particle size | SpringerLink).
These diverse experiences of synthesis and functionalization of nanoparticles for a multitude of application shaped the groundwork of the scientific approach I now always use. Then, when I was appointed as a Coating Researcher for EADS Innovation Works (Common Research Center of the Airbus Group) I transposed this approach to the control of the entire suite of interfaces (nano-, micro- and macroscopic) in the development of coatings for aeronautic structures’ protection. Between 2007 and 2018, one of my main research topics dealt with the protection of light alloys against corrosion by the development of breakthrough solgel-based coatings and encapsulation of corrosion inhibitors inspired by drug delivery systems. We built collaborative partnerships between aeronautics and academic labs and paint suppliers, and undertook preliminary work using nano-building blocks constructed from mesoporous (REVETEMENTS MESOSTRUCTURES COMPRENANT UN AGENT TEXTURANT PARTICULIER, POUR APPLICATION EN AERONAUTIQUE ET AEROSPATIALE (Brevets) – Data INPI / REVETEMENTS ANTICORROSION CHARGES EN PARTICULES MESOSTRUCTUREES (Brevets) – Data INPI) and hybrid UV-cured sol-gel-based matrices (Potentiality of UV-cured hybrid sol–gel coatings for aeronautical metallic substrate protection – ScienceDirect) to develop new approaches to active corrosion protection. Innovative approaches for the introduction of corrosion inhibitors were implemented using hybrid sol-gel encapsulation, especially with Dr Chris Barbé (CEO of Ceramisphere), and PYLOTE PARTICULES MÉSOSTRUCTURÉES CHARGÉES EN AGENTS ANTICORROSION OBTENUES PAR AÉROSOL (Brevets) – Data INPI. This work also explored ways to enhance the chemical compatibility with the coating matrix. Moreover we studied the automation of the sol-gel coating and UV-curing processes and I had the opportunity to present these last works at the 1 st industrial session at the XVII International Sol-Gel Conference in Madrid in 2013.
The other main topic of my work involved carbon-fiber-reinforced polymers (CFRP) which is a secondary substrate material for aeronautic structures, and the question of minor damage detection had not been addressed by coating solutions. For this reasons, I decided to focus on the development of impact- or temperature-sensitive coatings for health monitoring of CFRP. Common paint matrices and hybrid sol-gel matrices were explored to control the threshold of pressure or temperature required to transfer energy to the piezo/thermo-chromic pigments embedded in the coatings to facilitate a color change (see OliKrom video – AirbusGroup, the development of a PiezoKrom paint for aviation safety – OliKrom, smart colors; Hybrid piezochromic coatings for impact detection on composite substrates for aeronautic – ScienceDirect; and Choc Detection by Innovative Reversible Piezo chromic COatings for COMPosite Parts | ANR).
Finally, 4 years ago I moved to Safran Tech (research center of the Safran Group), as Coating Researcher and Sol-Gel and Nanomaterials Expert. My new playfields are engines, landing gears, nacelles, interior fittings such as seats, luggage boxes or galleys and much more! My current topics involving sol-gel materials deal with thermostable hybrid sol-gel bond-coat before thermal spraying coatings onto CFRP (PROCEDE DE REVETEMENT D’UN SUBSTRAT EN COMPOSITE (Brevets) – Data INPI) and high temperature oxidation protection of titanium alloys in collaboration with LMI and the LTDS. As always, I used the versatility of the sol-gel chemistry to explore the best way to reach specific macroscopic functionalities by control of hybrid interfaces at the nanoscale. This very rich research path allowed me to pass an HDR (French PhD’s Supervisor habilitation) in January 2021, which is unusual for industrial scientists. I am so grateful for this academic recognition, not only for scientific work in domains such as sol-gel chemistry but also for the strong bridge that it builds between academia and industrial needs for future R&D.
