Superhydrophobic Fiber Mats by Electrodeposition of Fluorinated Poly(3,4-ethyleneoxythiathiophene)

SiO2 Coated on ZnO Nanorod Arrays With UV-Durable Superhydrophobicity and Highly Transmittance on Glass

ZnO nanorod arrays were fabricated on glass through hydrothermal way. Then a thin SiO₂ film was covered on ZnO nanorod arrays using pulsed laser deposition (PLD) technique, and modified by stearic acid. It was found that SiO₂ film only had slight effects on the contact angle and transmittance of ZnO nanorod arrays. However, it had brought a huge improvement in the UV durability of superhydrophobic ZnO nanorod arrays. The results showed that the water contact angle remains constantly at 160.5° even UV irradiation time exceeded 50 h when the deposition time of PLD was about 10 min. This structure with UV-durable superhydrophobicity and highly transmittance on glass substrate can be served as front materials in solar cells.

Self-assembly of pendant functional groups grafted PEDOT as paracetamol detection material

In this paper, pendant functional group grafted EDOTs, such as EDOTCH₂NH₂, EDOTCH₂OH and EDOTCH₂SH, were selected as monomers for the preparation of their respective polymers via a common chemical oxidative polymerization method in the absence of CTAB by varying the [monomer]/[oxidant] ratios. The self-assembly mechanism of the polymers was systematically studied by discussing the hydrogen bonding effect, acidity and electron-donating ability, as well as the chain initiation and chain growth of the chemically oxidated polymerized monomers. These functional group grafted PEDOTs were applied to the electrochemical determination of paracetamol (PAR) to further investigate the effect of the pendant functional groups (-SH, -OH, -NH₂) on the electrochemical sensing behaviour of the polymers. The results indicated that the hydrogen bonding effect of the pendant functional groups was vital to the self-assembly of the polymer chains, and the PEDOTs with -OH and -SH groups had a tendency to self-assemble into a spherical structure, while the PEDOT with an -NH₂ group exhibited a fibrous structure. The electrochemical response of PEDOTs with functional groups was better than that that of PEDOT alone, and the highest electrochemical response was observed in PEDOT with an -SH group ([monomer]/[oxidant] = 1 : 8).

Improving the Electropolymerization Properties of Fluorene-Bridged Dicarbazole Monomers through Polyfluoroalkyl Side Chains

The facile functionalization of the fluorene scaffold at the 2,7-positions was utilized to provide access to two soluble carbazole-π-carbazole derivatives CFC-H1 and CFC-F1 featuring fully hydrogenated and polyfluorinated alkyl chains at the 9-position of the fluorene π-bridging unit, respectively. The optical and electrochemical properties of the new dicarbazoles were investigated. Their electrochemical polymerization over Pt and indium tin oxide electrodes allowed the generation of electroactive polymeric films, whose physicochemical characteristics were strongly dependent on the kind of alkyl chain present on the fluorene bridge. In particular, the electropolymerization of the polyfluorinated monomer allowed the fabrication of thin films with good electrical conductivity, reversible electrochemical processes, good electrochromic properties, and enhanced water repellency with respect to its nonfluorinated analogue.

Biomimetic polymeric superamphiphobic surfaces: their fabrication and applications

In this review, we summarize recent developments in polymeric superamphiphobic surfaces, including their design, fabrication, and potential applications.

Superhydrophobic coatings with high repellency to daily consumed liquid foods based on food grade waxes

The applications of superhydrophobic coatings in daily life are receiving increasing attention. Here, we report a general approach for preparing superhydrophobic coatings with high repellency to daily consumed liquid foods based on food grade waxes. The coatings are prepared by spray-coating the homogeneous wax suspensions in ethanol followed by annealing at 40 °C. The wax suspensions are formed by the heating dissolution-cooling precipitation-ultrasonication process thanks to the unique solubility of the waxes in ethanol. Ultrasonication of the wax suspension is helpful to improve superhydrophobicity by reducing the size of the wax microplatelets. Annealing at 40 °C could enhance mechanical stability of the coatings. The coatings are superhydrophobic with a water contact angle of 158.2° and a sliding angle of 7.3°. The coatings are resistant to intense water jetting and immersion in corrosive aqueous solutions. In addition, the coatings show excellent anti-adhesive properties for various liquid foods including cola, honey, milk and yoghourt. Moreover, the coatings are applicable onto different substrates (e.g., glass slide, PET plate and polyethylene plate) and could be prepared using different waxes (e.g., paraffin wax, beeswax and microcrystalline wax). We believe that the wax superhydrophobic coatings could find applications in various fields such as anti-adhesion of liquid foods, fruit preservation and anti-bioadhesion, etc.

A Rapid One-Step Process for Fabrication of Biomimetic Superhydrophobic Surfaces by Pulse Electrodeposition

Inspired by some typical plants such as lotus leaves, superhydrophobic surfaces are commonly prepared by a combination of low surface energy materials and hierarchical micro/nano structures. In this work, superhydrophobic surfaces on copper substrates were prepared by a rapid, facile one-step pulse electrodepositing process, with different duty ratios in an electrolyte containing lanthanum chloride (LaCl₃·6H₂O), myristic acid (CH₃(CH₂)₁₂COOH), and ethanol. The equivalent electrolytic time was only 10 min. The surface morphology, chemical composition and superhydrophobic property of the pulse electrodeposited surfaces were fully investigated with SEM, EDX, XRD, contact angle meter and time-lapse photographs of water droplets bouncing method. The results show that the as-prepared surfaces have micro/nano dual scale structures mainly consisting of La[CH₃(CH₂)₁₂COO]₃ crystals. The maximum water contact angle (WCA) is about 160.9°, and the corresponding sliding angle is about 5°. This method is time-saving and can be easily extended to other conductive materials, having a great potential for future applications.

Environmentally Friendly and Breathable Fluorinated Polyurethane Fibrous Membranes Exhibiting Robust Waterproof Performance

Waterproof and breathable membranes that provide a high level of protection and comfort are promising core materials for meeting the pressing demand for future upscale protective clothing. However, creating such materials that exhibit environmental protection, high performance, and ease of fabrication has proven to be a great challenge. Herein, we report a novel strategy for synthesizing fluorinated polyurethane (C6FPU) containing short perfluorohexyl (-C₆F₁₃) chains and introduced it as hydrophobic agent into a polyurethane (PU) solution for one-step electrospinning. A plausible mechanism about the dynamic behavior of fluorinated chains with an increasing C6FPU concentration was proposed. Benefiting from the utilization of magnesium chloride (MgCl₂), the fibrous membranes had dramatically decreased maximum pore sizes. Consequently, the prepared PU/C6FPU/MgCl₂ fibrous membranes exhibited an excellent hydrostatic pressure of 104 kPa, a modest water vapor transmission rate of 11.5 kg m^-2 d^-1, and a desirable tensile strength of 12.4 MPa. The facile fabrication of PU/C6FPU/MgCl₂ waterproof and breathable membranes not only matches well with the tendency to be environmentally protective but also fully meets the requirements for high performance in extremely harsh environments.

Specific Recognition of Human Influenza Virus with PEDOT Bearing Sialic Acid-Terminated Trisaccharides

Conducting polymers are good candidates for biosensor applications when molecular recognition element is imparted. We developed trisaccharide-grafted conducting polymers for label-free detection of the human influenza A virus (H1N1) with high sensitivity and specificity. A 3,4-ethylenedioxythiophene (EDOT) derivative bearing an oxylamine moiety was electrochemically copolymerized with EDOT. The obtained film was characterized by cyclic voltammetry, X-ray photoelectron spectroscopy, scanning electron microscopy, stylus surface profilometer, and AC-impedance spectroscopy. The trisaccharides comprising Sia-α2,6'-Gal-Glu (2,6-sialyllactose) or Sia-α2,3'-Gal-Glu (2,3-sialyllactose) were covalently introduced to the side chain of the conducting polymers as a ligand for viral recognition. Immobilization of sialyllactose was confirmed by quartz crystal microbalance (QCM) and water contact angle measurements. Specific interaction of 2,6-sialyllactose with hemagglutinin in the envelope of the human influenza A virus (H1N1) was detected by QCM and potentiometry with enhanced sensitivity by 2 orders of magnitude when compared with that of commercially available kits. The developed conducting polymers possessing specific virus recognition are a good candidate material for wearable monitoring and point-of-care testing because of their processability and mass productivity in combination with printing technologies.

The design of superhydrophobic stainless steel surfaces by controlling nanostructures: A key parameter to reduce the implantation of pathogenic bacteria

Reducing bacterial adhesion on substrates is fundamental for various industries. In this work, new superhydrophobic surfaces are created by electrodeposition of hydrophobic polymers (PEDOT-F₄ or PEDOT-H₈) on stainless steel with controlled topographical features, especially at a nano-scale. Results show that anti-bioadhesive and anti-biofilm properties require the control of the surface topographical features, and should be associated with a low adhesion of water onto the surface (Cassie-Baxter state) with limited crevice features at the scale of bacterial cells (nano-scale structures).

Integrated Anti-Icing Property of Super-Repellency and Electrothermogenesis Exhibited by PEDOT:PSS/Cyanoacrylate Composite Nanoparticles

Ice formation causes numerous problems in many industrial fields as well as in our daily life. Various functional anti-ice coatings have been extensively studied during the past several decades; however, the development of feasible ice-repellent surfaces with long-term stability has been found to be extremely difficult. Here, we report the conductive superhydrophobic coatings with freezing rain repellency that simultaneously possess electrothermogenic ability to rapidly melt newly formed frosts due to the Joule heat. The obtained films have high mechanical flexibility and abrasion resistance produced by composite nanoparticles of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) embedded in ethyl cyanoacrylate. In addition, excellent water repellency (corresponding contact angle >160°) and efficient heating ability (with an estimated energy consumption as low as 260.8 °C cm(2)/W) generated by applying voltage through the conductive film surface have been demonstrated. The proposed concept of combining super-repellency with electrothermal heating may provide a new strategy of addressing problems related to ice formation.

Spontaneous, Phase-Separation Induced Surface Roughness: A New Method to Design Parahydrophobic Polymer Coatings with Rose Petal-like Morphology

While the development of polymer coatings with controlled surface topography is a growing research topic, a fabrication method that does not rely on lengthy processing times, bulk solvent solution, or secondary functionalization has yet to be identified. This study presents a facile, rapid, in situ method to develop parahydrophobic coatings based on phase separation during photopolymerization. A comonomer resin of ethylene glycol diacrylate (EGDA) and 1H,1H,2H,2H-perfluorodecyl acrylate (PFDA) is modified with a thermoplastic additive (PVDF) to induce phase separation during polymerization. If applied to a glass substrate and photopolymerized, the EGDA/PFDA copolymer forms a homogeneous network with a single glass transition temperature (T(g)) and slight hydrophobicity (θ(w) ∼ 114°). When the resin is modified with PVDF, phase separation occurs during photopolymerization producing a heterogeneous network with two T(g) values. The phase separation causes differences in composition and cross-link density within the network, which leads to local variations in polymerization shrinkage across the nonconstrained material interface. Domains with higher cross-link densities shrink and contract toward the bulk material more dramatically, permitting the formation of rough surfaces with submicron sized spheres enriched in PVDF dispersed in a continuous matrix of EGDA/PFDA copolymer. Both the surface roughness and hydrophobic components in the resin render these surfaces parahydrophobic with θ(w) ∼ 150°, high water adhesion, and a similar morphology to rose petals observed in nature.

Solvent effects on electrosynthesis, morphological and electrochromic properties of a nitrogen analog of PEDOT

A new nitrogen analog of 3,4-ethylenedioxythiophene (EDOT), N-methyl-3,4-dihydrothieno[3,4-b][1,4]oxazine (MDTO), was electropolymerized in different solvents (deionized water, acetonitrile, and propylene carbonate) using LiClO4 as the electrolyte. The structure and performance of as-prepared PMDTO polymers were systematically studied by cyclic voltammetry, UV-vis spectroscopy, FT-IR, SEM, thermogravimetry, spectroelectrochemistry and electrochromic techniques. To our surprise, solvents had a major influence on the electropolymerization of MDTO and properties of the resultant polymers, including morphology, electrochemistry, electronic and optical properties, and electrochromics, etc. In aqueous solution, MDTO revealed the lowest onset oxidation potential (0.19 V) than in acetonitrile (0.48 V) and propylene carbonate (0.49 V). However, PMDTO films showed rather poor cycling stability in water, while outstanding stability in acetonitrile and propylene carbonate. Films prepared in propylene carbonate displayed a rather smooth morphology, lower band gap (1.65 eV), higher transparency (97.3%) and a contrast ratio (44.6%) at λ = 466 nm. PMDTO films obtained in acetonitrile showed significantly higher coloration efficiency (169.5 cm(2) C(-1)) than in other two solvents (∼ 97.6 cm(2) C(-1)) with a moderate contrast ratio (24.5%).

A bioinspired approach to produce parahydrophobic properties using PEDOP conducting polymers with branched alkyl chains

In nature, several plants and insects, such as the Rosa montana petals or the gecko foot, are highly hydrophobic but with an extremely high water adhesion. These properties are called parahydrophobic. Here, in order to reproduce such properties we have developed original 3,4-ethylenedioxypyrrole monomers containing branched alkyl chains in order to have intrinsically hydrophilic polymers. In certain conditions, the electrodeposited conducting polymer films are parahydrophobic due to the presence fibrous structures forming large agglomerates. On such surfaces, a water droplet deposited on them remains stuck even after a substrate inclination of 180°. Such properties are extremely interesting for applications in water harvesting, for example.

Superomniphobic and easily repairable coatings on copper substrates based on simple immersion or spray processes

Textures that resemble typical fern or bracken plant species (dendrite structures) were fabricated for liquid repellency by dipping copper substrates in a single-step process in solutions containing AgNO3 or by a simple spray liquid application. Superhydrophobic surfaces were produced using a solution containing AgNO3 and trimethoxypropylsilane (TMPSi), and superomniphobic surfaces were produced by a two-step procedure, immersing the copper substrate in a AgNO3 solution and, after that, in a solution containing 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES). The simple functionalization processes can also be used when the superomniphobic surfaces were destroyed by mechanical stress. By immersion of the wrecked surfaces in the above solutions or by the spray method and soft heating, the copper substrates could be easily repaired, regenerating the surfaces' superrepellency to liquids. The micro- and nanoroughness structures generated on copper surfaces by the deposition of silver dendrites functionalized with TMPSi presented apparent contact angles greater than 150° with a contact angle hysteresis lower than 10° when water was used as the test liquid. To avoid total wettability with very low surface tension liquids, such as rapeseed oil and hexadecane, a thin perfluorinated coating of poly(tetrafluoroethylene) (PTFE), produced by physical vapor deposition, was used. A more efficient perfluorinated coating was obtained when PFDTES was used. The superomniphobic surfaces produced apparent contact angles above 150° with all of the tested liquids, including hexadecane, although the contact angle hysteresis with this liquid was above 10°. The coupling of dendritic structures with TMPSi/PTFE or directly by PFDTES coatings was responsible for the superrepellency of the as-prepared surfaces. These simple, fast, and reliable procedures allow the large area, and cost-effective scale fabrication of superrepellent surfaces on copper substrates for various industrial applications with the advantage of easy recovery of the surface repellency after damage.

Controlling electrodeposited conducting polymer nanostructures with the number and the length of fluorinated chains for adjusting superhydrophobic properties and adhesion

Controlling the formation of surface nanostructures is highly important for various applications, and in particular for superhydrophobic properties.

Superhydrophobic and oleophobic surface from fluoropolymer-SiO2 hybrid nanocomposites

The fluoropolymer-SiO2 hybrid nanocomposite consisting of core-corona fluoropolymer-grafted SiO2 nanoparticle (NP) and poly(dodecafluoroheptyl methacrylate) (PDFHM) was obtained by radical solution polymerization of the vinyl trimethoxy silane (VTMS)-treated SiO2 NP with DFHM in this work. In H2O/tetrahydrofuran (THF) solution, PDFHM self-assembles into dendritic micelle and the increase in H2O volume is favorable for fluoropolymer-grafted SiO2 NPs to create dense fluoropolymer corona layer. It also shows that the addition of H2O to the THF suspension of fluoropolymer-SiO2 nanocomposite could cause a transfer for surface morphology of cast film from smooth film-covered aggregation to bare-exposed flaky aggregation and microsphere aggregation, which results in an increase in surface RMS roughness of cast film and induces a superhydrophobicity. Oleophobicity of cast film can be improved by thermal annealing, because strong surface self-segregation of PDFHM chains during thermal annealing process arouses a marked increase in surface fluorine content.

Elaboration of voltage and ion exchange stimuli-responsive conducting polymers with selective switchable liquid-repellency

In this work, we report the possibility to selectively switch by voltage and anion exchange the water-repellent properties, in comparison with the oil-repellent properties, of copolymers containing both fluorinated chain (EDOT-F8) and pyridinium (EDOT-Py(+)) moieties. Here, the fluorinated chains are necessary to reach superhydrophobic properties while the pyridinium moieties allow the switching in the wettability by counterion exchange. Because, conducting polymers can exist in their oxidized and reduced state, here, we report also the switching of their wettability by voltage. The best properties (superhydrophobic properties with low hysteresis and sliding and good oleophobic properties) are obtained for a % of EDOT-Py(+) of 25 %. Surprisingly, by reducing the polymer by changing the voltage, a selective decrease in the contact angle of water is observed, whereas that of oils (diiodomethane and hexadecane) remain unchanged, making it possible to have higher contact angles with diiodomethane than with water. Here, the switching in the wettability is due to the change of the water droplet from the Cassie-Baxter state to the Wenzel state by changing the voltage. Because of the presence of highly polar pyridinium groups and their perchlorate counterions, the wettability of oil droplets (diiodomethane and hexadecane) is not significantly affected. This effect is confirmed by changing the counterions with highly hydrophobic ones (C8F17SO3(-), Tf2N(-), or BF4(-)). Such materials are excellent candidates for oil/water separation membranes.

Homogeneous growth of conducting polymer nanofibers by electrodeposition for superhydrophobic and superoleophilic stainless steel meshes

Superhydrophobic and superoleophilic meshes are obtained by homogeneous electrodeposition of hydrocarbon poly(3,4-propylenedioxythiophene) nanofibers around the mesh wires.

Sticky superhydrophobic hard nanofibers from soft matter

Superhydrophobic soft and hard nanofibers with various water adhesions are obtained by electrodeposition of poly(3,4-propylenedioxythiophene) (ProDOT) derivatives containing two branched alkyl chains. In the case of the hard nanofibers, the fibers are vertically aligned to the substrate and their characteristics can be easily controlled but always with high water adhesion.