Superhydrophobic surfaces with low and high adhesion made from mixed (hydrocarbon and fluorocarbon) 3,4-propylenedioxythiophene monomers

International audienceThis work concerns new superhydrophobic surfaces, generated by replacing long fluorocarbon chains, which bioaccumulate, with short chains whilst at the same time retaining oleophobic properties. Here, is described the synthesis of novel original 3,4-propylenedioxythiophene derivatives containing both a short fluorocarbon chain (perfluorobutyl) and a hydrocarbon chain of various lengths (ethyl, butyl and hexyl). Superhydrophobic (contact angle water > 150° ) surfaces with good oleophobic properties (60° > contact angle hexadecane > 80° ) have been obtained by electrodeposition using cyclic voltammetry. Surprisingly, the lowest hystereses and sliding angles (Lotus effect) are obtained with the shortest alkyl chains due to the presence of microstructures made of nanofibers on the surfaces, whereas, the longest alkyl chains leads to nanosheets with high adhesion (Petal effect). Such materials are potential candidates for biomedical applications

Biobased non-isocyanate urethanized alkyd resins with non-oxidative crosslinking mechanism

Les résines alkydes sont les principaux liants des peintures et vernis modernes. Ces polymères sont obtenus par polycondensation de polyacides, polyols, acides gras et monoacides. L engouement croissant pour le développement durable pousse à la transition de produits pétrosourcés vers des produits biosourcés, à coûts et performances similaires. Pour les alkydes qui utilisent déjà en partie des matières premières renouvelables (acides gras, polyols), le challenge consiste à substituer les composants pétrosourcés restants tels que les dérivés phtaliques et benzoïques. Après un état de l art sur les alkydes, nous avons étudié les implications liées à la substitution de ces dérivés. Plusieurs résines alkydes biosourcées furent synthétisées et caractérisées par des mesures physico-chimiques (SEC, DSC, rhéomètre). Les peintures alkydes conventionnelles sèchent chimiquement par un mécanisme oxydatif qui requiert des sels de cobalt pour advenir en moins de 6 h. A cause de leur toxicité, ces sels sont sous pression par REACH. Nous avons proposé un mécanisme alternatif de réticulation non-oxydatif basé sur la réaction entre les groupes 2-oxo-1,3-dioxolane (ODO) et les amines primaires. La réaction modèle entre le carbonate de glycérol et l éthylenediamine nous a permis de comprendre la viabilité de ce mécanisme de réticulation. La création de groupes ODO a d abord été étudiée sur des huiles végétales afin de déterminer les conditions optimales et confirmer les possibles réactions d oligomérisation. Des alkydes portant ces groupes ODO ont pu être synthétisées et caractérisées, puis converties en résines alkydes uréthanisées sans isocyanate par réaction avec des diamines.Alkyd resins are the major binders used in surface coatings today. They are obtained by polycondensation of polybasic acids, polyols, fatty acids and monobasic acids. The raising sustainability awareness is pressuring for the transition from petrobased to biobased products with equivalent costs and performances. While conventional alkyd resins have high content in renewable raw materials such as fatty acids and polyols, replacement of petrobased raw materials such as phthalate and benzoic derivatives remained a challenge. After reviewing the current state-of-the-art regarding conventional alkyd resins, we focused on understanding the specific issues related to the synthesis of biobased alkyd resins. Several biobased alkyd resins were synthesized and characterized using techniques such as SEC, DSC and rheometer. Conventional alkyd paints chemically dry through an oxidative mechanism, which requires cobalt salts to occur in less than 6 h. These salts are under the scope of REACH because of their toxicity. As a possible alternative, we proposed a non-oxidative crosslinking mechanism based on the reaction of 2-oxo-1,3-dioxolane (ODO) groups and primary amines. This crosslinking mechanism was first studied with the model reaction between glycerol carbonate and ethylenediamine. The functionalization of ODO groups on vegetable oils was then studied as model molecule of alkyd resins, enabling the determination of optimal reaction conditions and that oligomerization occurs as a side reaction. Alkyd resins bearing ODO groups were then synthesized and characterized, then converted into non-isocyanate urethanized alkyd resins by reaction with diamines.NICE-Bibliotheque electronique (060889901) / SudocSudocFranceF

Parahydrophobic surfaces by electrodeposition of PEDOT polymers with aromatic groups

Special Issue: Self Cleaning Coatings (Omniphobic, Superhydrophobic, Superhydrophilic, Oleophobic)International audienceWe report the electropolymerization of five 3,4-ethylenedioxythiophene (EDOT) monomers containing different aromatic groups (phenyl, diphenyl, biphenyl, naphthalene, pyrene). While with phenyl, diphenyl, biphenyl and naphthalene the polymerization occurs on the EDOT moiety, with pyrene both the EDOT and the pyrene moieties polymerize. Their electrodeposition gives rise to different surface structures with parahydrophobic properties (water apparent contact angle θ > θY where θY corresponds to the Young angle of the smooth surface of the same materials). The highest properties are obtained with PEDOT-BiPh (θ = 134.6° and extremely high water adhesion). The results are due the combination of surface structures with intrinsically hydrophilic polymers (θY of the smooth polymer < 90°)

Post-functionalization of plasma treated polycarbonate substrates: An efficient way to hydrophobic, oleophobic plastics

International audienceThis work presents a new strategy of plasma treatment and post-functionalization of polycarbonate substrates in order to enhance their hydrophobic properties. While the plasma treatment is used to change the morphology and increase the roughness, the Huisgen reaction is used to decrease the surface energy or to add specific properties. Surface post-functionalization allows the covalent grafting of alkyl, aryl or perfluoroalkyl chains. The modified surfaces are investigated for their morphology, the observations performed show significant changes. The studies, made on the wettability, show important change in wettability with highly hydrophobic features (water apparent contact angle > 140°). Starting on a single polycarbonate surface, this multistep approach allows for the preparation of various polycarbonate surfaces with hydrophilic, oleophilic, highly hydrophobic, highly oleophobic or even fluorescent features to polycarbonate plastic surfaces

Synthesis, characterization and surface wettability of polythiophene derivatives containing semi-fluorinated liquid-crystalline segment

International audienceIn the scope of increasing our knowledge on the elaboration of smart surfaces, the aim of this work was to synthesize monomers as starting materials for the polymerization or copolymerization via electrochemical route. We report the synthesis and characterization of original structures containing a single phenyl unit bound, on one side, to a semi-fluorinated tail via a thioester connector and, on the other side, to a thiophene moiety. This design approach using cheap raw materials (a single phenyl ring as mesogenic core) associated to an electropolymerizable unit is of great interest in the development of liquid crystal low cost materials to build-up non-wetting surfaces based on the fluorophobic effect. The mesomorphic properties were characterized using differential scanning calorimetry and optical polarizing microscopy. The effect of the length of the fluorinated tail induced the formation of a smectic enantiotropic mesophase for F-hexyl and F-octyl tails. The polymerization of the films was performed in solution of sodium perchlorate in acetonitrile. Hydrophobic surfaces were obtained from the monomers containing a F-hexyl and F-octyl tail, while superhydrophobic surfaces (contact angle of water of 158°) were reached from the monomer containing a F-butyl tail

Characterization of air/water interface adsorption of a series of partially fluorinated/hydrogenated quaternary ammonium salts

International audienceThe adsorption at air/water interface of a series of partially fluorinated/hydrogenated quaternary ammonium salts was characterized by the determination of static and dynamic surface tension, critical micelle concentration, surface excess, area per molecule and Krafft temperature. In particular, the variation of these parameters was studied as a function of fluorinated and hydrogenated chain length.Modification of fluorinated and hydrogenated moieties allows to finely tune all the aforementioned physical surface properties: increasing the number of fluorinated carbon atoms boosts both effectiveness and efficiency of surfactant in reducing surface tension, kinetics of migration to interface are favored fastening reaching of equilibrium conditions, critical micelle concentration is reduced and surface excess is increased. Conversely increasing the length of the hydrogenated moiety reduces both effectiveness and efficiency of surfactant, migration to interface is slackened, c.m.c. is increased, and surface excess is depresses. Area per molecule and Krafft temperature appear to be affected mainly by the total number of carbon atoms introduced in the molecules whatever the nature of the substituent (fluorine or hydrogen)