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In this work, a bioinspired approach is used to prepare nanotubular structures with tunable hydrophobicity and water adhesion by a soft template surfactant-free electropolymerization in organic solvent. Various highly conjugated carbazole-based molecules are used as monomer. The presence of water in the organic solvent enables the formation of porous and rough nanostructures. Their shapes depend essentially on the nature of the monomer and the way it polymerizes. Various morphologies were obtained from nanoparticles network to horizontally or vertically aligned nanotubes. The nanostructured surfaces reach superhydrophobic properties and their dynamical behavior varies with the monomer from sticky to slippery. For example, using 9,3′:6′,9″-tercarbazole (TC) very long nanotubes are observed but their number is higher at constant potential. At high deposition charge, it is observed that most of the tubes are even collapsed leading to a strong increase of surface hydrophobicity with apparent contact angle up to 143° with strong water adhesion comparable to rose petals or gecko foot.

Hypothesis The formation of porous nanostructures on surfaces and the control of their size and shape is fundamental for various applications. The creation of nanotubes is particularly difficult to implement without the aid of hard and rigid templates. Recently, methods that form nanotubular structures in a straightforward manner and without direct templating, e.g. soft templating, have been highly sought after. Here we propose the use of “soft templating” via self-assembly of conducting monomers during electropolymerization in organic solvents as a mean to form porous, nanotubular features. Experiments Naphtho[2,3-b]thieno[3,4-e][1,4]dioxine (NaphDOT) is employed as monomer for electropolymerizations conducted in dichloromethane and chloroform containing varying amounts of water. SEM analyses of the resulting surfaces confirms the strong capacity of NaphDOT to form vertically aligned nanotubes. Polymerization solutions analyzed by DLS and TEM reveal the presence of micelles prior to electropolymerization, and the size of the micelles correlates with the inner diameter of the nanotubes formed. Findings We show that micelles in polymerization solutions are stabilized by both monomers and electrolytes. We propose a mechanism where reverse micelles are forming a soft-template responsible for the formation of porous nanostructures during electropolymerization in organic, non-polar solvents. In this mechanism, the monomer and electrolyte assume the role of surfactant in the reverse micelle system.

Here, templateless electropolymerization is employed to produce nanotubular structures from various thieno[3,4-b]thiophene-based monomers that differ in substituent structure and size, as well as the linker connecting the thieno[3,4-b]thiophene core and substituent. The formation of densely packed vertically aligned are obtained from monomers with a pyrene substituent and when a significant amount of water (CH2Cl2 + H2O) is included in the solvent. The geometrical parameters of the nanotubes are highly dependent on the electopolymerization method. A significant amount of air is trapped within the structure of the densely packed open nanotubes obtained with Qs = 100 mC cm−2 causing an increase in water contact angle (θw) up to 82.6° (intermediate state between the Wenzel and the Cassie-Baxter state), and θw can become even more hydrophobic by further modifying the deposition method or the electrolyte.

Using a bioinspired approach, we prepare poly(3,4-ethylenedioxypyrrole) (PEDOP) films with parahydrophobic properties, characterized by high apparent water contact angle and strong water adhesion. The films are made by electropolymerization and the influence of substitution by an alkyl chain of various length (from C4H9 to C14H29) on the 3,4-ethylenedioxy-bridge is reported. More precisely, the best properties are obtained from a length of C12H25 due to the formation of spherical nanoparticles.

The bioinspiration is one of the best ways to make a breakthrough in a field, and particularly in the wetting properties. Bioinspired by natural species such as rose petals and gecko foot and previous researches, nanotubular structures are prepared here by soft-template electropolymerization in organic solvent and using an original benzotrithiophene with a hydrophilic carboxyl group, as the monomer. The best results are obtained by cyclic voltammetry because of a much higher amount of gas bubbles released with this deposition method. Both nanoparticles and nanotubes are observed while the water content has an influence on the number of nanotubes. Even if the monomer has hydrophilic carboxyl group, the best films have both high hydrophobicity (apparent water contact angle up to 130.7°) and strong water adhesion (petal effect). These surfaces could be used in the future in applications such as water harvesting systems.

Electrodeposition is an effective and scalable method to grow desired structures on solid surfaces, for example, to impart superhydrophobicity. Specifically, copper microcrystals can be grown using electrodeposition by controlling deposition parameters such as the electrolyte and its acidity, the bath temperature, and the potential modulation. The aim of the present work is the fabrication of superhydrophobic copper-based surfaces by electrodeposition, investigating both surface properties and assessing durability under conditions relevant to real applications. Accordingly, copper-based layers were fabricated on Au/Si(100) from Cu(BF4)2 precursor by electrodeposition, using cyclic voltammetry and square-pulse voltage approaches. By increasing the bath temperature from 22 °C to 60 °C, the growth of various structures, including micrometric polyhedral crystals and hierarchical structures, ranging from small grains to pine-needle-like dendrite leaves, has been demonstrated. Without any further physical and/or chemical modification, samples fabricated with square-pulse voltage at 60 °C are superhydrophobic, with a contact angle of 160° and a sliding angle of 15°. In addition, samples fabricated from fluoroborate precursor are carefully compared to those fabricated from sulphate precursor to compare chemical composition, surface morphology, wetting properties, and durability under UV exposure and hard abrasion. Results show that although electrodeposition from fluoroborate precursor can provide dendritic microstructures with good superhydrophobicity properties, surfaces possess lower durability and stability compared to those fabricated from the sulphate precursor. Hence, from an application point of view, fabrication of copper superhydrophobic surfaces from sulphate precursor is more recommended.

Hypothesis In this original work, we aim to control both the surface wetting and fluorescence properties of extremely ordered and porous conducting polymer nanotubes prepared by soft template electropolymerization and post-grafting. For reaching this aim, various substituents of different hydrophobicity and fluorescence were post-grafted and the post-grafting yields were evaluated by surface analyses. We show that the used polymer is already fluorescent before post-grafting while the post-grafting yield and as a consequence the surface hydrophobicity highly depend on the substituent. Experiments Here, we have chosen to chemically grafting various fluorinated and aromatic substituents using a post-grafting in order to keep the same surface topography. Flat conducting polymer surfaces with similar properties have been also prepared for determining the surface energy with the Owens-Wendt equation and estimating the post-grafting yield by X-ray Photoemission Spectroscopy (XPS) and Time of Flight Secondary Emission Spectrometry (ToF-SIMS). For example, using fluorinated chains of various length (C4F9, C6F13 and C8F17), it is demonstrated that the surface hydrophobicity and oleophobicity do not increase with the fluorinated chain length due to the different post-grafting yields and because of the presence of nanoroughness after post-grafting. Findings These surfaces have high apparent water contact angle up to 130.5° but also strong water adhesion, comparable to rose petal effect even if there are no nanotubes on petal surface. XPS and ToF-SIMS analyses provided a detailed characterisation of the surface chemistry with a qualitative classification of the grafted surfaces (F6 > F4 > F8). SEM analysis shows that grafting does not alter the surface morphology. Finally, fluorescence analyses show that the polymer surfaces before post-treatment are already nicely fluorescent. Although the main goal of this paper was and is to understand the role of surface chemistry in tailoring the wetting properties of these surfaces rather than provide specific application examples, we believe that the obtained results can help the development of specific nanostructured materials for potential applications in liquid transport, or in stimuli responsive antimicrobial surfaces.

Electropolymerization of electron-rich aromatics/heteroaromatics to form conducting polymers is an easy and powerful technique to form surfaces of different nanostructures and hydrophobicity/wettability. Understanding the factors governing the growth of the polymer nanostructures and controlling the surface morphology are the big challenges for the surface and materials science. In this paper, we report the design and synthesis of a series of 3,4-phenylenedioxythiophenes (PheDOTs) substituted at the benzene ring with 2-naphthylmethyl-, 1-naphthylmethyl-, and 9-anthracenylmethyl-groups (2Na-PheDOT, 1Na-PheDOT, and 9Ant-PheDOT). They have been electropolymerized in either potentiostatic or potentiodynamic conditions to form the polymer surfaces of different morphologies. Even small changes in the structure of PheDOT monomers by varying the side groups (2-/1-naphthyl-or 9-anthracenyl-) result in the formation of very different polymer surface nanostructures: From monodirectionally growing (one-dimensional) vertically aligned nanotubes for 2Na-PheDOT to ribbonlike nanostructures (two-dimensional) for 1Na-PheDOT, and a mixture of these two structures for 9Ant-PheDOT. Moreover, the surfaces of the p[2Na-PheDOT] polymer, electrodeposited from the monomer 2Na-PheDOT and the dimer (2Na-PheDOT)2 (which have different solubilities and the reactivities on electropolymerization, but formally lead to the polymer of the same chemical structure), show very different nanostructures. In contrast to 2Na-PheDOT, which forms vertically aligned nanotubes of the polymer on the surface, the polymerization of (2Na-PheDOT)2 leads to spherical particles [three-dimensional (3D)] when Bu4NClO4 is used as an electrolyte and a membrane structure with spherical holes (3D) in the case of more hydrophobic Bu4NPF6. The importance of water for gas bubble formation (O2 and H2) during electropolymerization and creation of the surface nanostructures has been demonstrated and discussed. The formation of these different nanostructures is accompanied by different wettability of the surface, from hydrophilic (with an apparent water droplet contact angle of θw ∼40-70°) to highly hydrophobic (θw up to 129-134°). The sticky, parahydrophobic surface formed from 1Na-PheDOT showed high adhesion to water, with no water droplets moving after inclination of the surface to 90° (rose-petal effect). Copyright © 2019 American Chemical Society. Government Council on Grants, Russian Federation The authors thank the Center Commun de Microscopie Appliquée (CCMA, Univ. Nice Sophia Antipolis) for the realization of the SEM images. E.L.K. thanks the Russia President Ph.D. Scholarship for studying abroad to visit Bangor University and also thanks Act 211 Government of the Russian Federation for financial support (contract No. 02.A03.21.0006). I.S. thanks the Erasmus+ student mobility program for supporting her internship at Bangor University. I.F.P. thanks SIFE-NPU for generous startup funding.

With the development of water purification technologies, the usage of superhydrophobic meshes is increased but the fabrication of durable and cost effective superhydrophobic meshes is still challenging. Here, the formation of hierarchical copper fractals on stainless steel meshes and their superhydrophobicity without any physical or chemical modification were studied. In addition, the improvement of superhydrophobicity of surfaces during storing in a glass bottle for a long time (> one year) is reported. The structures were prepared using electrodeposition method applying cyclic voltammetry and square pulse deposition approaches on stainless steel meshes with 50 µm, 100 µm and 200 µm pore sizes. The prepared layers are a composition of copper with varying amounts of cuprite (Cu2O) depending on deposition method and mesh pore size. As-prepared cyclic voltammetry layer on 100 µm mesh showed the parahydrophobicity with the contact angle of 154° but a large sliding angle. The one-year stored samples in the glass bottle showed superhydrophobicity with the contact angles larger than 150° and sliding angles in the range of 4°–20°. The observed improvement of superhydrophobicity is a great success in the realm of industrial water purification, while most other proposed samples by the others have problems related to the durability of superhydrophobicity.

Copper based layers were fabricated on gold/silicon (100) substrates by using square pulse electrodeposition at different deposition temperatures. The predominant crystalline plane on Cu2 O samples at temperatures higher than 30 °C is (111), which is the most hydrophobic facet of Cu2 O cubic structure. Different crystallite structures such as semivertical leaves, fractal trees, and octahedral pyramids were formed on the surface. These water-repellent samples have hierarchical structures, including octahedral pyramid microstructures with small spherical balls on them and well-branched micrometric vertical leaves on the surface. They provide a suitable surface for trapping air pockets inside the structure and increasing the water contact angle up to 154°. This approach may be applicable to the large-scale preparation of water-repellent surfaces as superhydrophobicity can be achieved in a one-step deposition process without any secondary modifications.

In the aim to tune the surface nanostructures and the resulting surface hydrophobicity and water adhesion, we report the preparation of surfaces by electropolymerization of 3,4-ethylenedioxypyrrole (EDOP) and 3,4-propylenedioxypyrrole (ProDOP) with both a short fluorocarbon chain (C4F9) and an alkyl chain of various length (C2H5 to C12H25). The surface properties are very different following the choice of the polymerizable core (EDOP or ProDOP) and the alkyl chain length. The PEDOP polymers are here easier to electrodeposit while the ProDOP could be electrodeposited only with long alkyl chains (≥C8H17). Their electrodeposition leads to the formation of both nanoparticles and wrinkles. The highest properties with apparent contact angle (θw) ≈ 141° and extremely strong water adhesion (parahydrophobic properties) are obtained with EDOP monomers and using intermediate alkyl chains (C6H13 and C8H17). Such properties could be exploited in the future in applications where the control of the interaction forces with the media is required such as in oil/water separation membranes or in water harvesting systems.

In this original work, we wanted to prepare surfaces with both high hydrophobicity and strong water adhesion, as observed on rose petals or gecko foot. The surfaces are prepared by electropolymerization and using thieno[3,4-b]thiophene monomers with various branched alkyl chains. Here, branched alkyl chains are used to their lower hydrophobic properties compared to linear alkyl chains and fluorinated chains. It is observed a change from structured to smooth when the branched alkyl chain length increases. Using short branched alkyl chains, the surfaces are mainly composed of wrinkles and nanoparticles displaying high hydrophobicity ( $${\theta }_{\mathrm{w}}$$ up to 134.9°) combined with strong water adhesion, as observed on rose petals even if $${\theta }_{\mathrm{w}}$$ is less important. Dynamic contact angle measurements show that their water adhesion is extremely strong and water droplets remain stuck on them. By adding H2O in the solvent (CH2Cl2 + H2O), it is possible to release gas bubbles (H2 and/or O2) in-situ leading to more porous surfaces but here it is observed an increase of surface hydrophilicity. These original polymer surfaces have potential applications in water harvesting systems or oil/water separation membranes, for example.

Hypothesis Controlling the size and the shape of nanostructures on surfaces is fundamental for various applications while the formation of porous structures such as nanotubes is particularly difficult. The templateless electropolymerization is a choice process that not only forms nanostructured surfaces, but also can tune their morphologies using different monomers. Experiments In this work, we used this soft-template and surfactant free electropolymerization in organic solvent to deposit for the first time carbazole-based monomers. Five different conjugated carbazole-based monomers are tested here. Findings We show that the shape of surfaces nanostructures is highly dependent on the amount of water present in the organic solvent and on the molecular structure of the carbazole monomers. Different morphologies are obtained from fibers to vertically aligned nanotubes and even porous membranes, depending on the monomer and on the electropolymerization method. The nanostructured surfaces reach superhydrophobic properties and their dynamical non-wetting behavior varies with the monomer and the electrochemical parameters.

To facilitate potential applications of water-in-supercritical CO

To facilitate potential applications of water-in-supercritical CO2 microemulsions (W/CO2 μEs)efficient and environmentally responsible surfactants are required with low levels fluorination. As wellas being able to stabilize water-CO2 interfaces, these surfactants must also be economical, prevent bioaccumulation and strong adhesion, deactivation of enzymes, and also be tolerant to high salt environments.Recently, an ion paired catanionic surfactant with environmentally-acceptable fluorinated C6-tails wasfound to be very effective at stabilizing W/CO2 μEs with high water-to-surfactant molar ratios (W0) up to~50 (Sagisaka, M. et al. Langmuir, 2019, 35, 3445–3454). As the cationic and anionic constituentsurfactants alone did not stabilize W/CO2 μEs, this was the first demonstration of surfactant synergisticeffects in W/CO2 microemulsions. The aim of this new study is to understand the origin of these intriguingeffects by detailed investigations of nanostructure in W/CO2 microemulsions using high pressure smallangle neutron scattering (HP-SANS). These HP-SANS experiments have been used to determine theheadgroup interfacial area and volume, aggregation number and effective packing parameter (EPP). TheseSANS data suggest the effectiveness of this surfactant originates from increased EPP and decreasedhydrophilic/CO2-philic balance, related to a reduced effective headgroup ionicity. This surfactant bearsseparate C6F13-tails and oppositely-charged headgroups, and was found to have a EPP value similar tothat of a double C4F9-tail anionic surfactant (4FG(EO)2), which was previously reported to be one of mostefficient stabilizers for W/CO2 μEs (maximum W0 = 60-80). Catanionic surfactants based on this newdesign will be key for generating super-efficient W/CO2 μEs with high stability and water solubilization.

Here, we control the surface hydrophobicity and the adhesion of water droplets by electrodeposition of poly(3,4-ethylenedioxypyrrole) (PEDOP) and poly(3,4-propylenedioxypyrrole) (PProDOP) with branched alkyl chains placed preferentially on the bridge to favor the formation of nanofibers. Branched alkyl chains of various sizes from very short (C3) to hyperbranched (C18) are studied because they have lower surface hydrophobicity than long alkyl or fluoroalkyl chains (preferable for parahydrophobic properties). The electrodeposition is much more favored with the PEDOP derivatives because the ProDOP films are more soluble. However, the formation of nanoparticles is favored with the PEDOP polymers in contrast to the formation of fibers, resembling the wax nanoclusters observed on lotus leaves, with the ProDOP polymers. With both these PEDOP and PProDOP derivatives, it is possible to reach parahydrophobic properties characterized by a sticking behavior toward water droplets. This kind of surfaces could be used in the future in water harvesting systems, for example.

This work uses an innovative strategy to show a combination of highly hydrophobic films with fluorescence and anti-bacterial properties. Pyrene grafted with linear and branched alkyl chains of various length (from C4H9 to C12H25) were electropolymerized and their wetting behavior and surface morphology were first analyzed. The presence of microstructured spherical particles (1 µm) induces a high increase in the surface hydrophobicity (θw,max = 132°) even if the polymers are intrinsically hydrophilic (θY = 79–88°), while the surface oleophobicity decreases. The emission of the pyrene monomers and polymers is in the green region (λem = 479–515 nm) and showed to be related with the size and the architecture of the chain. The differences in the aggregations and interactions of the oligomers induce a blue-shift and a thinner spectral band for the branched pyrenes compared to the linear ones. A crescent batochromic and hypsochromic shift are observed for linear and branched chains, respectively, as the number of carbons increase. The polypyrenes also have a potential application to serve as coatings towards to prevention of biofilm formation. A reduction between 30–70% was observed for the bacterial adhesion and between 91–94% for the biofilm formation for S. aureus and P. aeruginosa strains. Here we showed for the first time that hydrophobic surfaces bearing hydrocarbon chains without fluorine atoms can be used towards to repel bacteria. Furthermore, the pyrene molecules lead to fluorescent and microstructured hydrophobic surfaces by a one-step electropolymerization process and the combination of these properties enhances the range of applications for these surfaces.

In the current work, we developed a novel method to fabricate hybrid surfaces consisting of mixed hydrophilic/superhydrophobic properties. These surfaces specifically consist of a regular array of hydrophilic pillars (displaying a receding contact angle lower than 90°) surrounded by a superhydrophobic thinner layer made via the electropolymerization of a fluorinated monomer. Then, we determined the wetting properties of various forms of this complex surface, i.e., displaying different surface properties, by specifically determining their advancing (θa) and receding (θr) contact angles. Two main parameters were varied: the pillar density (from 21.2% to 6.5% based on using a spacing d between pillars varying from 25 to 45 micrometers) and the polymer charge density (from 0 to 100 mC cm-2). We observed that, for low charge density values, only the ground surface was covered by the hydrophobic polymers; while for higher charge density values, polymerization reached higher levels on the lateral surfaces of the nonconductive cylindrical pillars, eventually up to their top surfaces and covering them for the highest charge densities. This feature gave us an additional parameter that we could use to control the surface wettability. We also found that contact angles (advancing and receding) increased markedly with increasing polymer charge density above a critical value (which was higher for receding angles). And we measured advancing and receding contact angles to, respectively, increase and decrease with increasing pillar density. We interpreted qualitatively these behaviors, the main point being the importance of the impalement (null, partial or total).

In the aim to obtain parahydrophobic materials (both high contact angles and high hysteresis) for possible applications in water harvesting systems, we report the synthesis of novel 3,4-ethylenedioxypyrrole (EDOP) and 3,4-propylenedioxypyrrole (ProDOP) monomers with aromatic rings on the 3,4-alkylenedioxy bridge and the resulting conducting polymer films were prepared by electropolymerization. We show that the surface properties can be tuned by the nature of the aromatic ring (phenyl, biphenyl, diphenyl, naphthalene, fluorene, and pyrene) and the polymerizable core (EDOP or ProDOP). The best results are obtained with both EDOP and diphenyl, with which extremely high hydrophobic properties (up to 116°) are obtained, even if the polymers are intrinsically hydrophilic. These surfaces could be applied in the future, for example, in water harvesting systems or in water/oil separation membranes. The synthesis strategy is extremely interesting, and many other molecules will be envisaged in the future.

Use of metal oxide thin layers is increased due to their good durability under environmental conditions. In this work, the repeatable nanostructured crystalite Cu2O thin films, developed by electrodeposition method without any physical and chemical modifications, demonstrate good hydrophobicity. Copper (I) oxide (Cu2O) layers were fabricated on gold/Si(1 0 0) substrates by different electrodeposition methods i.e. galvanostatic deposition, cyclic voltammetry, and pulse potentiostatic deposition and using copper sulfate (in various concentrations) as a precursor. The greatest crystalline face on prepared Cu2O samples is (1 1 1) which is the most hydrophobic facet of Cu2O cubic structure. Indeed, different crystallite structures such as nanotriangles and truncated octahedrons were formed on the surface for various electrodeposition methods. The increase of the contact angle (θw) measured by the rest time, reaching to about 135°, was seen at different rates and electrodeposition methods. In addition, two-step deposition surfaces were also prepared by applying two of the mentioned methods, alternatively. In general, the morphology of the two-step deposition surfaces showed some changes compared to that of one-step samples, allowing the formation of different crystallite shapes. Moreover, the wettability behavior showd the larger θw of the two-step deposition layers compared to the related one-step deposition layers. Therefore, the highest observed θw was related to the one of two-step deposition layers due to the creation of small octahedral structures on the surface, having narrow and deep valleys. However, there was an exception which was due to the resulted big structures and broad valleys on the surface. So, it is possible to engineer different crystallites shapes using the proposed two-step deposition method. It is expected that hydrophobic crystallite thin films can be used in environmental and electronic applications to save energy and materials properties.

Effects of functionalization and grafting of TiO2, CeO2, and SiO2 nanoparticles (NPs) were investigated, and toxicity of pristine, functionalized, and grafted NP towards Daphnia magna was measured. Surface functionalization of NP with amine groups decreased hydrophobicity of NP. When NPs were hydrophilic, they were less toxic than hydrophobic NP towards D. magna. Grafting agents influenced toxicity: no toxicity of NP was observed when bio-based and hydrogenated synthetic polymers were used, whereas perfluorinated polymers induced a higher toxicity.

Several species in nature have special wetting properties such as Lotus leaves or rose petals. Both the surface morphology and surface energy play a fundamental role. In particular, nanofibers were found to be exceptional surface structures due to a possible control in both water hydrophobicity and water adhesion as a function of their length, diameter, their orientation to the substrate or the spacing between them. Here, in the aim to prepare nanofibers with high liquid-repellent properties using conducting polymers, we have synthesized 3,4-propylenedioxypyrrole (ProDOP) derivatives with hydrocarbon and fluorocarbon chains in the 3-position, keeping the NH group free (important condition to lead to nanofibers thanks to hydrogen bonds). Different hydrocarbon and fluorocarbon chain lengths are studied. We obtain, for example, nanofibers of different size with octyl, decyl and C4F9 chains (intermediate hydrophobicity) with different liquid-repellent properties and liquid adhesion properties. More precisely, PProDOP-H8 is close to superhydrophobic properties (low water adhesion) while PProDOP-H10 is parahydrophobic (high water adhesion). This works could find many potential applications in the nanotechnology field as water harvesting surfaces, liquid separation membrane, and in anti-bioadhesion. Due to the presence of free NH groups, these materials could also be used as pH-sensitive materials while the nitrogen could also be easily functionalized.

Previous studies [Langmuir, 2014, 30, 21, 6057–6063, Phys. Chem. Chem. Phys., 2017,19, 23869–23877] have shown that surfactants bearing highly-methylated alkyl tails (so-called “hedgehog” groups) are able to reduce the limiting surface tension at the aqueous critical micelle concentration (CMC) to γCMC ~24 mN m−1, which is considerably lower than for common n-alkyl tail surfactants (30–40 mN m−1). In the quest to develop even more effective and efficient non-fluorinated surfactants, this study introduces new amphiphiles having double and triple hedgehog tails and examines relationships between surfactant structure and aqueous solution properties. Of particular interest are links between γCMC, the effective hydrophobic-tail layer density (ρlayer) and total number of carbon and silicon atoms in the hydrophobic tails (NC+Si). Interestingly, γCMC is seen to depend on ρlayer rather than NC+Si, and ρlayer ~0.63 g cm−3 appears to be an optimal surface layer density for promoting low γCMC. For a surfactant bearing trimethysilyl (TMS) chain tips, exchanging the surfactant counterions from Na+ to Mg2+ reduced γCMC from 23.8 mN m−1 to 21.5 mN m−1, which is very low for a hydrocarbon surfactant, and comparable to typical fluorinated surfactants. A new measure of the ability of different surfactants to lower surface tension is proposed, which is helpful for targeting low surface energy (tension) non-fluorinated surfactants. In terms of both γCMC and CMC TMS-terminal tips are shown to be key groups for promoting hydrophobicity and/or low surface tensions.

The formation of highly ordered surface structures is fundamental for various applications. Due to their rapidity of implementation and their cost, the templateless processes are extremely interesting alternatives to the use of templates or lithographic processes. In the aim to prepare porous structures such as nanotubes, the templateless electropolymerization was find to be a unique process. Based on previous works, we have synthesized 3,4-naphthalenedioxythiophene (NaPhDOT) monomers substituted with alkyl chains (n = 2 to 10), phenyl and naphthalene substituents. In particular, NaphDOT substituted with naphthalene (NaphDOT-Na) leads for the first time to relatively densely packed nanorings while their internal diameter is controllable with the number of deposition scans. Compared to previous works, which lead to nanotubes from non-substituted NaphDOT and 3,4-phenylenedioxythiophene substituted with naphthalene (PheDOT-Na), with NaphDOT-Na we observed a very important decrease in the polymer growth. As a consequence, only the initial peripherical nucleation around the gas bubbles is possible leading to nanorings while their growth in nanotubes is impeded by their low conductivity.

With an aim to control the surface hydrophobicity and water adhesion, as observed on various natural surfaces, novel 3,4-propylenedioxythiophene (ProDOT) monomers having one and two 3-trimethylsilylpropyl (TMS) groups were synthesized and subjected to electropolymerization to form surface coatings. The monomer ProDOT is employed owing to its tendency to form fibrous structures by electropolymerization [T. Darmanin, F. Guittard, Mater. Chem. Phys. 146 (2014) 6–11], whereas the TMS groups generate very low surface energies comparable to short chain fluorocarbons [N. M. Kovalchuk, et al., Colloids Surfaces A 604 (2020) 125277.]. It is shown that even though these two types of monomer lead to fibrous structures, the dimensions of the fibers as well as the wetting properties are different. The monomer with only a single TMS group (ProDOTSiMe3) generates extremely long nanofibers with only low surface roughness. The resulting surfaces have extremely high apparent contact angles (θw) up to 141.7° and strong water adhesion, similar to rose petals or gecko feet. On the other hand, the analogue with two TMS groups (ProDOT(SiMe3)2) forms short nanofibers but with extremely high surface roughness. The resulting surfaces are superhydrophobic with θw > 160° and ultra-low water adhesion (hysteresis and sliding angles < 1°), similar to lotus leaves. These results point to interesting applications offering control over water adhesion whilst maintaining high hydrophobicity.

A smart stimuli responsive surface is fabricated by the subsequent electro-copolymerization of pyrene monomers followed by a basic and acid treatment, respectively. Copolymers of fluorinated pyrenes and pyreneacetic acid were produced with different molar concentration of each monomer (0, 25, 50, 75 and 100% of Py-nF6 vs. Py-COOH) by an electrochemical process. Two different perfluorinated pyrenes containing ester and amide groups are used to reach superhydrophobic properties. The relation of those bonds with the final properties of the surface is reported. The pH-sensitive group of the Py-COOH allows the surfaces to be reversibly switched from superhydrophobic (w > 150o and very low hysteresis) to a hydrophilic behavior (w < 90o). The amide and ester bonds influence the recovery of the original wettability after both basic and acid treatment. If the fluorinated homopolymer with ester bonds is insensitive to basic and acid treatment due to its superhydrophobic properties with ultra-low water adhesion, the recovery of the original wettability for the copolymers is much more important with amide bonds due to their lower pH-sensitivity. This strategy offers the opportunity to access superhydrophobic films with switchable wettability by a simple pH treatment. The films showed to be a good tool to use towards biological applications as bacterial-resistant film when superhydrophobic or bacterial-adherent film when hydrophilic, for example.

Roughness parameters are traditionally obtained for the surface characterization of microfluidic devices as these are easily computed from height profiles. However, these provide limited topological information on channel geometry needed for fluid flow or fluid retention optimization. In this study, topological measures from Minkowski functionals and cluster analysis were evaluated if these can detect percolating channels or fluid traps in plasma-etched surfaces. Unlike Minkowski functionals, cluster analysis distinguished the onset of microchannel formation from the discontinuous percolation transition. The size of the irregularly shaped microchannel was obtained from the percolation order parameter ( P ). Thus, P may be used as a topological measure for the automatic detection and geometry evaluation of channels and cavities for various microfluidic applications. Besides percolation, Minkowski functionals and cluster analysis may be used to obtain fractal properties of nano-patterns for nanofluidic device design.

Numerous exceptional properties can be observed in nature. Among these properties, parahydrophobic feature is of interest. This property describes material with high adhesion with water such as rose petals or gecko foot. Such kind of surface presents a real potential for applications in the field of water harvesting systems. In this work, we report a new synthetic strategy to mimic this property. Here, we combine three strategies in one. First, a monomer is electropolymerized in order to form the starting structured surface. Then, nanoparticles are grafted on the surface to increase the structuration and consequently to create the reactive surface. Finally, the grafted surface is post-functionalized (Huisgen reaction) with various aryl alkynes to control the surface chemistry and energy. This strategy allows to reach surfaces with both very high hydrophobic properties (θ = 140°) and high water adhesion. This work also includes the surface wettability, roughness and morphology investigation in order to study the impact of the starting monomer structure and post-functionalization on the surface properties.

This work reports for the first time the use of electrodeposition to prepare platform mesh substrates with controlled wettability by post -functionalization. First, PEDOT nanofibers with azido (N 3 ) groups are electrodeposited around the mesh wires. Then, the Huisgen reaction is used using various alkynes (alkyl, perfluoroalkyl and aryl) in order to graft different hydrophobic substituents on the surface. This work shows the huge impact of the post -treatment on both the surface morphology and wettability. This also shows the possibility to start from a unique platform mesh to prepare oleophilic ( θ θ > 150°) or highly oleophobic ( θ > 120° with hexadecane)/superhydrophobic surfaces ( θ > 150°). Such kind of technology could be used as separation devices to oil and water, for example.

Nature is a constant source of inspiration for researchers and engineers. In this work, we study the wettability of various species from the genus Echeveria. All species studied present very strong hydrophobic properties with various water adhesions. Echeveria ‘Perle von Nurnberg' has properties very close to superhydrophobicity with low water adhesion (sliding angle α = 15° and contact angle hysteresis H = 9°) while Echeveria pallida and Echeveria runyonii are completely sticky (parahydrophobic) and water droplets do not move even if the surface is inclined to 90°. This work shows that most of the differences in the hydrophobic properties depend on the amount of wax crystallization. However, Echeveria pulvinata shows special wettability results. Their leaves possess long hairs. When a water droplet is placed on the surface, the water droplet is completely sticky. When the size of the droplets becomes critical, the water droplets spread across the leaf surface displaying superhydrophilic properties. More investigations reveal that the hairs are highly hydrophobic and rough due to the presence of wax crystals while the bottom of the surface is smooth and hydrophilic. Such materials are excellent candidates for water harvesting systems and oil/water separation membranes.

International audience; Due to their small size, nanoparticles possess unique properties. Cerium oxide nanoparticles have already been studied for their capacity to adsorb and neutralize toxic compounds including organophosphates. By covalently grafting these nanoparticles to a thickening polymer, their potential aggregation resulting in a loss of surface area and their potential toxicity are avoided. Indeed, copolymers easily form gels in water at neutral pH thanks to low interactions occurring between polymeric chains; thus, gels can be spread on membrane supports to afford protective barriers. However, as we demonstrated previously, a formulation step of these hydride nanoparticle-polymeric compounds is necessary to overcome the cracking of the coating during drying. This work reports the impact of many factors on the efficiency of a new active Topical Skin Protectant (aTSP) including: (1) the presence of CeO2 nanoparticles in the protective coating and their amount, (2) their grafting to a perfluorocarbon thickening polymer and (3) the formulation of the CeO2 nanoparticle-grafted polymer. The combination of all the benefit parameters led to a very effective new aTSP against paraoxon penetration. The major in vitro diffusion studies were performed in Franz-type diffusion cells on two artificial membranes (silicone and Strat-M) and final validation on ex vivo human skin. The comparison of 24h-exposure between membrane results indicated a difference in the behavior between the two artificial supports and the biological model; Strat-M membranes seeming closer to human skin results. Therefore, positive results regarding occlusive conditions should be confirmed with human skin.