Bacterial Colonization of Low‐Wettable Surfaces is Driven by Culture Conditions and Topography

Effect of surface low‐wettability on bacterial colonization has become a prominent subject for the development of antibacterial coatings. However, bacteria's fate on such surfaces immersed in liquid as well as causal factors is poorly understood. This question is addressed by using a range of coatings with increasing hydrophobicity, to superhydrophobic, obtained by an atmospheric plasma polymer method allowing series production. Chemistry, wettability, and topography are thoroughly described, as well as bacterial colonization by in situ live imaging up to 24 h culture time in different liquid media. In the extreme case of superhydrophobic coating, substrates are significantly less colonized in biomolecule‐poor liquids and for short‐term culture only. Complex statistical analysis demonstrates that bacterial colonization on these low‐wettable substrates is predominantly controlled by the culture conditions and only secondary by topographic coating's properties (variation in surface structuration with almost constant mean height). Wettability is less responsible for bacterial colonization reduction in these conditions, but allows the coatings to preserve colonization‐prevention properties in nutritive media when topography is masked by fouling. Even after long‐term culture in rich medium, many large places of the superhydrophobic coating are completely free of bacteria in relation to their capacity to preserve air trapping

Etude et modélisation des phénomènes interfaciaux solide/liquide (relation entre le mouillage, la physico-chimie et la morphologie des surfaces. Optimisation des propriétés de surface par traitement mécanochimique)

Ce travail s'inscrit dans le cadre d'une recherche pluridisciplinaire, à la fois fondamentale et expérimentale, et se situe au carrefour de la physico-chimie des interfaces et de la mécanique des fluides. Une goutte de liquide déposée sur une surface solide peut, selon les propriétés de l'interface solide/liquide, s'étaler de façon très variée. La compréhension du phénomène de l'étalement devient indispensable lorsqu'on cherche à optimiser de nombreux processus technologiques. Dans un premier temps, on étudie de façon expérimentale les différentes phases d'étalement d'une goutte de liquide déposée sur une surface horizontale et rugueuse. L'originalité de la modélisation proposée repose sur l'intégration dans un système d'équations d'un coefficient matriciel qui prend en compte la topographie de la surface mouillée. Dans un second temps, la modification des propriétés de mouillage des surfaces métalliques par des traitements mécanochimiques spécifiques a permis de quantifier son impact sur la physico-chimie des interfaces solide/liquide. Il a été démontré qu'un des paramètres de mouillages (l'angle au retrait) s'avère être une mesure pertinente pour contrôler l'homogénéité du traitement de surfaces. De plus, des corrélations ont pu être déterminées, au moyen de techniques chimiométriques d'analyses de données, entre les caractéristiques de l'abrasif contenu dans la formulation mécanochimique (taille, forme, dureté), la morphologie finale de la surface traitée (paramètre topographique 3 D) et la fonctionnalité de la surface traitée. Enfin, les études de différentes formulations ont permis, grâce à des analyses spectroscopiques infrarouges, de rechercher les corrélations entre la composition des formulations initiales et celles des dépôts. Les valeurs des énergies de surface, mesurées à l'aide des angles de contact avec les différents liquides sondent ont permis d'évaluer la polarité finale des surfaces métalliques issues du traitement mécanochimiques étudié.LYON1-BU.Sciences (692662101) / SudocSudocFranceF

Thermodynamic and Kinetic Study of Diels–Alder Reaction between Furfuryl Alcohol and N-Hydroxymaleimides—An Assessment for Materials Application

International audienceThe study of Diels–Alder reactions in materials science is of increasing interest. The main reason for that is the potential thermoreversibility of the reaction. Aiming to predict the behavior of a material modified with maleimido and furyl moieties, 1H NMR and UV-Vis solution studies of the Diels–Alder reaction between furfuryl alcohol and two N-hydroxymaleimides are explored in the present study. Rate constants, activation energy, entropy, and enthalpy of formation were determined from each technique for both reacting systems. Endo and exo isomers were distinguished in 1H NMR, and the transition from a kinetic, controlled Diels–Alder reaction to a thermodynamic one could be observed in the temperature range studied. A discussion on the effect of that on the application in a material was performed. The approach selected considers a simplified equilibrium of the Diels–Alder reaction as the kinetic model, allowing materials scientists to evaluate the suitability of using the reacting molecules for the creation of thermoresponsive materials. The proposed approach determines the kinetic constants without the direct influence of the equilibrium constant value, thereby allowing a more objective data analysis. The effects of the selection of kinetic model, analytical method, and data treatment are discusse

Influence of Plasma Chamber Set-Up on the Surface Modification of Non-Vulcanized and Pure SBR Rubber Treated at Radio-Frequencies Air Plasma

International audienceNon-vulcanized styrene-butadiene rubber thin films were exposed to Radio-Frequency low-pressure air plasma. Two different configurations corresponding to direct and downstream RF plasmas were compared. Optical emission spectroscopy provided information about plasma composition and temperature. The plasma treated SBR surfaces were characterized by contact angles and XPS spectroscopy. Two different phenomenological mechanisms are proposed to describe the observed differences according to the plasma configuration used and account for the impact of the activated gas phase on the structure of plasma-treated non-vulcanized SBR surfac

La Conception industrielle de produits – Volume 2 : Spécifications, déploiement et maîtrise de la performance

National audienc

Understanding the impact of poly(allylamine) plasma grafting on the filtration performances of a commercial polymeric membrane

International audienc

Textile with Durable Janus Wetting Properties Produced by Plasma Polymerization

The development of coating methods that enable us to combine antagonist properties on a single material is a real challenge. This active research topic can impact, for instance, the textile field to engineer fabrics with liquid-repellent properties on one side and superhydrophilic properties on the opposite side. In this context, we have developed an easy surface functionalization process that provides durable Janus wetting properties to fabrics. On the basis of plasma-enhanced chemical vapor deposition (PECVD), we report a simple and reproducible three-step functionalization method that led to a coating with superhydrophobic and superoleophobic properties on one side of the porous substrate and superhydrophilic properties on the opposite side. A thin, fluorinated polymer film was deposited on one side, while the other side was functionalized with a polymer coating made of maleic anhydride, subsequently hydrolyzed to provide carboxylic acid groups to the surface. Static contact angles up to 169° with water and 162° with hexadecane were obtained on the fluorinated side of the fabric thanks to an appropriate combination of surface chemistry with dual-scale surface roughness. In addition, roll-off angles of 6 and 14° with water and hexadecane, respectively, were measured on this side of the sample. As for the opposite side, the hydrolyzed plasma polymer made of maleic anhydride enables us to obtain a surface that fully absorbs water and hexadecane. In addition, these tremendous properties were durable because no significant change was observed after aging and washing cycles. This simple surface functionalization process based on plasma polymerization is an innovative solution for the fabrication of textile with durable waterproof and breathable properties. Besides, the described concept can be adapted to numerous other applications that require Janus properties to porous substrates

Grafting Diels-Alder moieties on cellulose nanocrystals through carbamation

International audienceThe Diels-Alder reaction is a promising click chemistry for the design of advanced materials from cellulose nanocrystals (CNCs). Transferring such chemistry to cellulose nanocrystals requires the precise grafting of reactive Diels-Alder moeities under heterogeneous conditions without compromising the nanocrystals morphology. In this study toluene diisocyanate is used as a spacer to graft Diels-Alder moieties viz the furyl and protected maleimido moieties onto cellulose nanocrystals. A factorial experimental design reveals that reaction time and reactant molar ratio positively affect the grafting efficiency, as evidenced by FTIR and CHNS elemental analysis. The surface degree of substitution was analyzed via CHNS elemental analysis and XPS and found to range between 0.05 to 0.30, with a good agreement between the two techniques. 13C CP/MAS NMR confirmed that the grafted moieties and CNCs are intact after reaction. Side reactions were also observed and their impact on performing controllable click chemistry between cellulose nanocrystals is discussed