Hydrophilic Functionalities Research Articles

Electropolymerization processing of side-chain engineered EDOT for high performance microelectrode arrays

Microelectrode Arrays (MEAs) are popular tools for in vitro extracellular recording. They are often optimized by surface engineering to improve affinity with neurons and guarantee higher recording quality and stability. Recently, PEDOT:PSS has been used to coat microelectrodes due to its good biocompatibility and low impedance, which enhances neural coupling. Herein, we investigate on electro-co-polymerization of EDOT with its triglymated derivative to control valence between monomer units and hydrophilic functions on a conducting polymer. Molecular packing, cation complexation, dopant stoichiometry are governed by the glycolation degree of the electro-active coating of the microelectrodes. Optimal monomer ratio allows fine-tuning the material hydrophilicity and biocompatibility without compromising the electrochemical impedance of microelectrodes nor their stability while interfaced with a neural cell culture. After incubation, sensing readout on the modified electrodes shows higher performances with respect to unmodified electropolymerized PEDOT, with higher signal-to-noise ratio (SNR) and higher spike counts on the same neural culture. Reported SNR values are superior to that of state-of-the-art PEDOT microelectrodes and close to that of state-of-the-art 3D microelectrodes, with a reduced fabrication complexity. Thanks to this versatile technique and its impact on the surface chemistry of the microelectrode, we show that electro-co-polymerization trades with many-compound properties to easily gather them into single macromolecular structures. Applied on sensor arrays, it holds great potential for the customization of neurosensors to adapt to environmental boundaries and to optimize extracted sensing features.

Chemical extraction and its effect on the properties of cordleaf burbark (Triumfetta cordifolia A. rich) fibres for the manufacture of textile yarns

Tropical Triumfetta cordifolia (TC) fibre extracted from the equatorial region of Cameroon has been characterized as a potential fibre for textiles. An investigation of extraction parameters to soften this fibre is crucial to use it as a biobased material in the spinning process. To obtain textile quality fibres, 34 sodium hydroxide extraction tests were carried out to study the effect of extraction conditions on its characteristics. Thus, three levels of concentrations (0.5, 1.0 and 1.5 wt%), temperatures (80, 100 and 120 °C) and durations (120, 180 and 240min) were used for extraction by cooking, and at room temperature, durations of 120, 150 or 180 min with three concentrations (2.5, 3.0 and 3.5 wt%) were considered. Only 6 combinations produced fibres that were clear and soft to the touch, without defects (corrugations, stuck fibres) and without residual bark epidermis at the macroscopic scale. For these fibres, the dissolution of non-cellulosic substances, morphological, physical, thermal and mechanical properties depended on the austerity of the alkaline retting. Under mild conditions, the SEM surfaces of the fibres showed large residues of the middle lamella, which made the lignin content (10 wt%) and hydrophilic function higher. Under medium conditions, the fibre surfaces were clean and slightly wrinkled (at 80 °C; 120min). Under severe conditions, heterogeneous transverse shrinkage and wrinkling were observed and accompanied by cellulose degradation (39 wt%) with a significant reduction in tenacity at 16cN/tex. The medium extraction conditions were considered more effective, and their fibres showed cellulose content up to 49 wt%, density up to 1.39 g cm−3, “Fickian” moisture absorption kinetics with saturation up to 11 wt%, thermal stability up to 237 °C, Young's modulus up to 3.7 GPa, tensile strength up to 113 MPa and tenacity up to 40cN/tex. These new results were compared with lignocellulosic textile fibres in the literature, showing similarity with banana, sisal and jute fibres.

Solventless Polymer-Grafted Mesh for Rapid and Efficient Oil–Water Separation

We report a solventless bilayer strategy for grafting hydrophilic poly(methacrylic acid) (PMAA) onto metal meshes. The bilayer nanocoating consisted of ultrathin PMAA brushes grafted onto a highly crosslinked primer that binds to each mesh wire. The enrichment of hydrophilic functionalities on the PMAA-grafted mesh surface improved the surface hydration and underwater oil repellency over the PMAA-crosslinked mesh, which contributed to the formation and stabilization of continuous water films between mesh wires to reject oil penetration in repeated uses. The vapor-based nanocoating process maximized the retention of pore openings for high-flux oil–water separation. The retained permeability, together with the enhanced oil repellency, enabled the PMAA-grafted mesh to achieve excellent gravity-driven oil–water separation, with an oil rejection rate higher than 99%, water flux exceeding 50,000 L m–2 h–1, and flux decay less than 3% after 20 cycles of reuse. More importantly, the PMAA-grafted mesh preserved high separation efficiency and flux stability under conditions of high salinity and extreme pH.

PH-Responsive Water-Soluble Chitosan Amphiphilic Core–Shell Nanoparticles: Radiation-Assisted Green Synthesis and Drug-Controlled Release Studies

This work aims to apply water radiolysis-mediated green synthesis of amphiphilic core-shell water-soluble chitosan nanoparticles (WCS NPs) via free radical graft copolymerization in an aqueous solution using irradiation. Robust grafting poly(ethylene glycol) monomethacrylate (PEGMA) comb-like brushes were established onto WCS NPs modified with hydrophobic deoxycholic acid (DC) using two aqueous solution systems, i.e., pure water and water/ethanol. The degree of grafting (DG) of the robust grafted poly(PEGMA) segments was varied from 0 to ~250% by varying radiation-absorbed doses from 0 to 30 kGy. Using reactive WCS NPs as a water-soluble polymeric template, a high amount of DC conjugation and a high degree of poly(PEGMA) grafted segments brought about high moieties of hydrophobic DC and a high DG of the poly(PEGMA) hydrophilic functions; meanwhile, the water solubility and NP dispersion were also markedly improved. The DC-WCS-PG building block was excellently self-assembled into the core-shell nanoarchitecture. The DC-WCS-PG NPs efficiently encapsulated water-insoluble anticancer and antifungal drugs, i.e., paclitaxel (PTX) and berberine (BBR) (~360 mg/g). The DC-WCS-PG NPs met the role of controlled release with a pH-responsive function due to WCS compartments, and they showed a steady state for maintaining drugs for up to >10 days. The DC-WCS-PG NPs prolonged the inhibition capacity of BBR against the growth of S. ampelinum for 30 days. In vitro cytotoxicity results of the PTX-loaded DC-WCS-PG NPs with human breast cancer cells and human skin fibroblast cells proved the role of the DC-WCS-PG NPs as a promising nanoplatform for controlling drug release and reducing the side effects of the drugs on normal cells.

Preparation of dopamine/Ag‐modified graphene oxide/polysulfone/poly(vinylidene fluoride) ultrafiltration membrane with hydrophilic and antibacterial dual function

AbstractTo improve the hydrophilicity and long‐lasting bacterial inhibition of poly(vinylidene fluoride) (PVDF) ultrafiltration membranes, DA/Ag‐GO/PSF/PVDF hybrid ultrafiltration membranes were prepared with PVDF and polysulfone (PSF) as substrates, graphene oxide (GO) as additives, and dopamine (DA) and silver as surface modifications. The structure and performance of PSF/PVDF hybrid membranes were investigated by SEM, FTIR, contact angle, filtration flux, and bacterial inhibition tests. The results showed that with the addition of GO, the hydrophilicity of the PSF/PVDF hybrid membranes were enhanced, the water flux tended to be increased, the retention rate of bovine serum albumin were maintained above 94%, and the bacterial inhibition against Gram‐negative and positive bacteria were obvious. When GO was added at 0.2 wt%, the contact angle of the hybrid membrane decreased from 87° to 69°, the water flux increased from 406.05 to 650.52 L m−2 h−1, the flux recovery increased from 49.18% to 84.40%, and the resistance to organic contamination was significantly improved.

Fragmentation Mechanism in a Nitrogen Dielectric Barrier Discharge Plasma on Fluoropolymer Polymer Films.

Due to their chemical inertness and low friction coefficient, fluoropolymers are today widely employed in sectors of activity as diverse and distinct as the textile industry, architectural sector, and medicine. However, their low surface energy results in poor adhesion, for example, when used for a component in a composite device with multiple other materials. Among the techniques used to enhance their adhesion, atmospheric pressure discharges provide a fast and low-cost method with a reduced environmental impact. Although this approach has proven to be efficient, the different chemical and physical processes in the discharge remain not fully understood. In this study, fluoropolymer surfaces were modified using an atmospheric pressure dielectric barrier discharge in a nitrogen and organic precursor environment. To prevent any damage to fluoropolymer surfaces, the dissipated power in the discharges was tuned by applying a duty cycle. Evidence shows that plasma treatment allows for the incorporation of oxygen and nitrogen in the surface resulting in the formation of hydrophilic functionalities such as carbonyl groups both in ketone and amide form, amine, and hydroxyl groups after 180 s of treatment. Overall, the data reveal that the discharge duty cycle has more effect on the oxygen and carbon content in the coating than the precursor concentration. In addition, increasing the precursor concentration limits the molecular fragmentation and nitrogen incorporation into the coating. These experiments enable the building of a better fundamental understanding of the formation mechanism of such chemical moieties at the fluoropolymer surface.

2D-QSAR and CoMFA Models for Antitubercular Activity of Scalarane-Type Sesterterpenes

A series of scalarane sesterterpenes were prepared using heteronemin (1) as a primary precursor. Combined with the scalarane derivatives obtained from natural sources, a total of 22 antitubercular scalaranes were used to build QSAR models based in the 2D-QSAR and CoMFA approaches. Both models indicated the influences of substitutions in the vicinity of C-12 and C-16 of the scalaranes. A 2D-QSAR model suggested the necessity of hydrophilic functionalities on the peripherals with hydrophobic cores, and the lowering steric repulsion to improve the potential energy. This was complemented by the pictorial CoMFA model, which indicated the importance of the positive electrostatic with shortened steric extension crowning over C-12 and the lengthy negative functionalities extended from C-16.

MXenes Thin Films: From Fabrication to Their Applications.

Two-dimensional MXenes possessed exceptional physiochemical properties such as high electrical conductivity (20,000 Scm−1), flexibility, mechanical strength (570 MPa), and hydrophilic surface functionalities that have been widely explored for energy storage, sensing, and catalysis applications. Recently, the fabrication of MXenes thin films has attracted significant attention toward electronic devices and sensor applications. This review summarizes the exciting features of MXene thin film fabrication methods such as vacuum-assisted filtration (VAF), electrodeposition techniques, spin coating, spray coating, dip-coating methods, and other physical/chemical vapor deposition methods. Furthermore, a comparison between different methods available for synthesizing a variety of MXenes films was discussed in detail. This review further summarizes fundamental aspects and advances of MXenes thin films in solar cells, batteries, electromagnetic interference shielding, sensing, etc., to date. Finally, the challenges and opportunities in terms of future research, development, and applications of MXenes-based films are discussed. A comprehensive understanding of these competitive features and challenges shall provide guidelines and inspiration for further growth in MXenes-based functional thin films and contribute to the advances in MXenes technology.

Influence of sampling area and extraction method on the thermal, physical and mechanical properties of Cameroonian Ananas comosus leaf fibers

The wide dispersion of the properties of plant fiber bundles further limits their use. In this study, manual and retting methods were used to extract fiber bundles from the available and underutilized Ananas comosus (AC) leaf waste in Cameroon. These fibers were sampled in three zones: base, middle and head. The fibers extracted by retting in the different zones were found to have better thermal stability. A 2.5% solution of sodium hypochlorite was used for bleaching the various pineapple fibers. Density, fineness, functional groups, mechanical properties, water absorption and morphology of different fibers were characterized. Density and fineness decreased from the head to the base of the leaf and were lower for manually obtained fiber bundles. The peaks of the infrared spectra associated with the functional groups of the pineapple fibers change very little along with the leaf but are clearly more pronounced for the fibers extracted manually. Fibers in the middle of the leaf have been found to have slightly better mechanical and water absorption properties. All fiber bundles can rapidly absorb water following simple exponential kinetics. Bleaching partially removes non-cellulosic materials from the fibers with a transverse shrinkage effect, which improves their fineness, density and hydrophilic function. Unfortunately, it reduces their tensile strength and fracture toughness. These results show that the whole leaf can be used without restriction to extract manually or by retting the fiber bundles intended for the manufacture of textiles and composites. Furthermore, bleaching with sodium hypochlorite seems ineffective due to fiber degradation.

Hydrophobic, partially hydrophobic, and hydrophilic ZnO@SiO2 nanoparticles as fluorescent partitioning tracers for oil sensing applications

(a) Schematic representation of various functionalities on the surface of ZnO@SiO 2 nanoparticles. The partially hydrophobic (PH-NPs, S2), hydrophobic (HP-NPs, S3), and hydrophilic (H-NPs, S4) functionalities were developed on the surface of ZnO@SiO 2 NPs using various silanes having methyl, octyl, and amino groups, respectively. (b,c) The fluorescent NPs (S4) stayed entirely in the water phase due to the presence of –NH 2 group (hydrophilic nature), while the fluorescent NPs (S3) moved completely toward the oil phase due to the presence of octyl-group (hydrophobic nature) on their surface. However, the luminescent NPs (S2) were shifted toward the interface between two phases due to partially hydrophobic character ( CH 3 ) on their surface. • ZnO@SiO 2 NPs were synthesized via a modified sol–gel Stober protocol. • Surface functionalities were attained by co-condensation of various silanes. • Surface chemistry and partitioning behavior of ZnO@SiO 2 NPs were investigated. • ZnO@SiO 2 NPs have excellent fluorescence stability in aqueous environments. • Stability of ZnO@SiO 2 NPs was examined under harsh reservoir conditions. Fluorescent nano-tracers are being utilized for oil sensing applications in the reservoir. In this work, we developed various hydrophobic, partially hydrophobic, and hydrophilic zinc oxide encapsulated silica nanoparticles (ZnO@SiO 2 NPs) as smart nano-agents for oil sensing applications. The surface of ZnO@SiO 2 NPs was functionalized by co-condensation using various silanes in combination with tetraethyl orthosilicate (TEOS). Cryogenic TEM images display the average size of ZnO QDs (S0) and ZnO@SiO 2 nanoparticles (S1) around ∼5.3 nm and ∼50 nm, respectively. The surface chemistry and partitioning behavior of photoluminescent ZnO@SiO 2 NPs were investigated before and after mixing with the model oil under normal and UV light. The chemical and photoluminescence (PL) stability of ZnO@SiO 2 NPs was monitored in harsh reservoir conditions, such as variable temperature (30–100 °C) and high salinity (0–80 g L −1 ) environment. The results demonstrated that the surface modification and functionalization of these nano-agents with different functional groups (methyl, octyl) improved the nano-agents’ selectivity and stability after changing their hydrophilic-hydrophobic surface characters. This work is opening new research in the field of oil sensing, which promotes their potential utilization as cost-effective and efficient fluorescent tracer materials for the oil exploration industries.

Carbon dots decorated cadmium sulphide heterojunction-nanospheres for the enhanced visible light driven photocatalytic dye degradation and hydrogen generation

Carbon dots (C-dots) developed from beetroot is used for the rational design of cadmium sulphide based heterojunction photocatalysts (C-dots@CdS) using hydrothermal technique. The crystal structure, phase, morphology and optical characteristics of the synthesised materials are determined using X-ray diffraction (XRD), High resolution transmission electron microscopy (HR-TEM), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV–Visible diffuse reflectance spectroscopy (UV-DRS), photoluminescence spectroscopy (PL spectroscopy), BET adsorption, X-ray photoelectron spectroscopy (XPS) and electrochemical studies. Using C-dots@CdS catalytic system, a superior photocatalytic activity relative to the undecorated CdS is observed. Among the C-dots@CdS samples, the CdS loaded with 6 wt% of C-dots exhibited enhanced hydrogen evolution rate compared with other samples considered for the study. CdS nanospheres modified with C-dots (6 wt%) resulted in the photocatalytic hydrogen evolution rate of 1582 µmolg−1 against 849 µmolg−1 evolution rate obtained for CdS nanospheres within 3 h. In spite of being 0D/0D type nano-heteroarchitecture, C-dots@CdS system obtained an apparent quantum yield of 6.37 % for the catalytic dosage of 20 mg under the irradiation of visible light. CdS in the C-dots@CdS system serves as the light harvester while C-dots with discernible edges can maintain the continuous supply of photo-excited charge carriers and hence can reduce the charge-carrier recombination. Further, the photodegradation of crystal violet dye using the optimised dosage of C-dots@CdS-6 exhibited an efficiency of 97.3 % in 120 min of visible light irradiation under neutral conditions. The detailed kinetic study reveals that the mechanism of photodegradation of crystal violet dye using C-dots@CdS system can be described using pseudo-second-order kinetics. The presence of oxygen rich hydrophilic surface functionalities of C-dots, the formation of near-surface heterojunction and the suitable band structure of C-dots@CdS system leading to the optimum charge carrier separation kinetics can be attributed to the enhanced photocatalytic performance. This work offers a promising strategy to develop bio-derived C-dots based heterojunction photocatalyst to address the burgeoning energy and environmental demands.

Improvement of fouling resistance and mechanical reinforcement of polyacrylonitrile membranes by amino‐functionalized multiwalled carbon nanotubes for membrane bioreactors applications

AbstractThe goal of the current research is to simultaneously improve the fouling resistance and mechanical properties of polyacrylonitrile ultrafiltration membrane for membrane bioreactors (MBR) applications by a relatively easy method. For this purpose, amino‐functionalized carbon nanotubes (NH2‐MWCNTs) were employed, which have exceptional mechanical properties, hydrophilic functions, and good interaction with polyacrylonitrile. It was used to fabricate nanocomposite membranes with different MWCNTs contents. The rheological and thermodynamical aspects of the phase separation process were investigated to understand the mechanism of the membrane formation. The related characteristics including morphological, mechanical, and chemical properties of the membrane as well as its performance were studied. In the end, the synthesized membranes were used in an MBR setup for further investigations. The Pure water flux data shows considerable improvement from 810 LMH for the neat membrane to 1055 LMH for the 0.3 wt% NH2‐MWCNTs nanocomposite membrane. Mechanical enhancement was confirmed with about a 24% increase in the tensile strength and 61% for elongation at break. The membrane with 0.3 wt% NH2‐MWCNTs revealed the best porosity, fouling resistance, and performance in MBR with 95% flux recovery ratio and 64% improvement in permeated flux compared to the neat membrane.

Nanoemulsion-Coated Ni-Fe Hydroxide Self-Supported Electrode as an Air-Breathing Cathode for High-Performance Zinc-Air Batteries.

To improve the energy conversion efficiency and durability of zinc-air batteries (ZABs) for large-scale implementations, here we propose an "air-breathing" strategy to significantly enlarge triple-interfaces with intensified mass transfer. By dip-coating the aerophilic perfluorochemical compounds (PFC) and amphiphilic ionomers into the self-supported electrodes, (1) the high solubility of O2 in the PFC nanoemulsions greatly increases triple-phase boundaries and facilitates the efficient supply/removal of O2 from the electrolyte; (2) the ionomers with hydrophobic and hydrophilic functionalities enable fast gas, water, and ion transport to the triple-phase boundaries; and (3) the self-supported electrode without binder ensures fast electron transfer while the firm integration prevents catalyst shedding. By applying this strategy, the ZABs show a high power density of 115 mW cm-2 and a narrow discharge/charge gap of 0.64 V at 10 mA cm-2 and a long-cycling durability (over 1000 h). This work provides a universal approach to promote gas-evolving reactions for electrochemical applications.

Functionalization of polyurethane for infection‐resistance surface

AbstractPolyurethane (PU) has an eminence potential to be used as a urinary catheter because of its physicochemical properties. The biofilm accumulation on the surface of polyurethane is the biggest hindrance for its usage as a safe and prolonged catheter. Herein, the antimicrobial polyurethane was developed via wet chemistry method. Alkaline hydrolysis using NaOH was used for the generation of hydrophilic (amine) functionality on polyurethane surface. The reactant concentration and reaction time was investigated in terms of good amine functionality. The amine content at optimized condition was found to be ~4 μM/g in 8 h after treating with 10% NaOH. The surface morphology of hydrolyzed polyurethane was characterized using SEM and atomic force microscopy (AFM) technique, which confirmed the formation microdomains on the PU surface due to hydrolysis. Chlorohexidine digluconate (CLX) was used as model drug and CLX was simply incorporated by immersion of the PU in the CLX solution. The immobilization of drug was confirmed using surface chemistry analysis, that is, X‐ray photoelectron spectroscopy and energy‐dispersive X‐ray mapping technique. The cumulative release of drug was observed with varying concentration of drug. Excellent bacteriostatic and bactericidal efficiency were observed for drug immobilized polyurethane against both gram‐positive bacteria S. aureus and gram‐negative bacteria E. coli. The designed CLX‐PU film did not allow the bacteria to adhere on its surface and mitigate the risk of biofilm formation.

Molecular insight into water desalination through functionalized graphenylene nanosheet membranes

Molecular dynamics simulations were performed to investigate the performance of functionalized graphenylene membranes for seawater desalination in terms of water permeability and salt rejection. For this purpose, the functionalized graphenylene nanosheet was inserted in the simulation cell containing sodium and chloride ions. Then, molecular simulations were done for four different membrane-based systems (P1, P2, P3, and P4) under different external pressures to obtain the water permeability and salt rejection of all systems. The results demonstrated that system P1 owning fluorinated pore, shows the best performance among all systems with permeability of 11,032 L.m−2.h−1.bar−1 and 99.4% salt rejection at P = 10 MPa. Also, system P3 with combined functional fluorine and hydroxyl groups at the pore, revealed the permeability of 9293 L.m−2.h−1.bar−1 and 100% salt rejection at P = 5 MPa. Therefore, the hydrophilic chemical functions improve the desalination performance of membrane, which can be considered in design of water desalination systems.

Solvo-thermal Assisted-Synthesis; Experimental and Theoretical Characterization; and Biological Evaluations of Azo-Chelator-Ligand Chelates of Fe(II) and Zn(II) ions

Background and Objectives: The resistance of microbes against anti-bacteriological drugs leading to countless deaths and terminal ailments remains a basis for concern. Hence, the main interest of this study was to design, synthesize and report unusual compounds with basic hydrophilic moieties plus hydrophobic functions for anti-bacteriological studies.
 Materials and Methods: Analytical (melting points, micro-analysis (C. H.N.S) magnetic susceptibility (µeff), molar conductance plus solubility test) methods; spectral (Fourier Transform Infrared(FTIR)), electrospray ionization mass spectrometry (ESI-MS), nuclear magnetic resonance (1H- plus 13C-NMR), electronic(UV-Vis)) measurements; theoretical (DFT) evaluations were utilized for the characterization of the chelator and its chelates. All synthesized compounds were examined for antimicrobial and antioxidant potentials while the chelator was singly evaluated for solvent extractive capacity.
 Results: A nitrogenous based chelator-ligand, (E)-1-(((4,6-dimethylpyrimidin-2-yl)imino)methyl) naphthalen-2-ol(LH) synthesized through reflux-condensation reaction of 2-amino-4,6-dimethylpyrimidine with 2-hydroxy-1-napthaldehyde was acquired. Further reflux of the chelator-ligand with bivalent ions of iron-sulphate and zinc-acetate salts plus 2,2’-bipyridine resulted into separate bivalent-heteroleptic metallic chelates. The deprotonated nitrogen of the amine moiety and carbon of the carbonyl gave rise to the chelator-ligand with N2O2 chromophore detected around the metallic atom in the chelates. The µeff data plus UV-Vis spectral values of the chelates conformed to 6-coordinate octahedral geometry. All the chelates were high spin and non-ionic in dimethylsulfoxide (DMSO). The antimicrobial and antioxidant screening of the compounds presented moderate to fantastic results, while the metallic extractive proficiency of the chelator showed outstanding extractability for Fe2+ and Zn2+ions with an efficiency of 79.34% and 51.92% correspondingly.
 Conclusion: All the synthesized compounds are novel and demonstrated prospective biological, plus metallic ions’ extractive potentials required for designs plus isolation of products also for such actions.

Supramolecular Self-Associations of Amphiphilic Dendrons and Their Properties.

This review presents precisely defined amphiphilic dendrons, their self‐association properties, and their different uses. Dendrons, also named dendritic wedges, are composed of a core having two different types of functions, of which one type is used for growing or grafting branched arms, generally multiplied by 2 at each layer by using 1→2 branching motifs. A large diversity of structures has been already synthesized. In practically all cases, their synthesis is based on the synthesis of known dendrimers, such as poly(aryl ether), poly(amidoamine) (in particular PAMAM), poly(amide) (in particular poly(L‐lysine)), 1→3 branching motifs (instead of 1→2), poly(alkyl ether) (poly(glycerol) and poly(ethylene glycol)), poly(ester), and those containing main group elements (poly(carbosilane) and poly(phosphorhydrazone)). In most cases, the hydrophilic functions are on the surface of the dendrons, whereas one or two hydrophobic tails are linked to the core. Depending on the structure of the dendrons, and on the experimental conditions used, the amphiphilic dendrons can self‐associate at the air‐water interface, or form micelles (eventually tubular, but most generally spherical), or form vesicles. These associated dendrons are suitable for the encapsulation of low‐molecular or macromolecular bioactive entities to be delivered in cells. This review is organized depending on the nature of the internal structure of the amphiphilic dendrons (aryl ether, amidoamine, amide, quaternary carbon atom, alkyl ether, ester, main group element). The properties issued from their self‐associations are described all along the review.

An atmospheric water electrolyzer for decentralized green hydrogen production

The necessity of ultrapure water and water-transport infrastructure pose grand challenges in renewable-energy-assisted water electrolysis to produce green hydrogen. Directly accessing atmospheric water should offer a decisive solution because it provides ∼13 trillion kiloliters of pure water at any given instant. We show that the central challenge for atmospheric water electrolysis is related to the water-sorption kinetics of the proton-conducting membrane where state-of-the-art membranes critically fail. A proof-of-concept atmospheric water electrolyzer is demonstrated with a graphene oxide proton-conducting membrane, which has nearly three times higher water-sorption kinetics and ten times higher hydration number than a Nafion membrane due to capillary water condensation and the abundant presence of hydrophilic functionalities. At a wind velocity of ∼50 km/h, this electrolyzer delivers nearly 18 mL/h/cm2 of green hydrogen directly from the feedstock of atmospheric water. Because this electrolyzer does not require water-transport infrastructure, it can be placed almost anywhere, which offers opportunities for decentralized green hydrogen production.

Water-stable Zn-based metal-organic framework with hydrophilic-hydrophobic surface for selective adsorption and sensitive detection of oxo-anions and pesticides in aqueous medium

Given the importance of surface-functionalized materials with improved adsorption and detection properties for targeted applications, we report herein the design and development of a water-stable luminescent Zn-based metal-organic framework (Zn-MOF) with the hydrophobic-hydrophilic surface property. The developed luminescent Zn(II)-MOF {[Zn(PA2-)(dmbpy)](DMF)}n was synthesized via a solvothermal method using pamoic acid (PA) and 5,5′-dimethyl-2,2′-bipyridine (dmbpy) with free functional groups (hydroxyl and methyl groups). Careful single-crystal structure analysis revealed a 3-dimensional hydrogen-bonded network with a one-dimensional channel and functionalized surface. The surface functionalization was achieved through rational choice of ligands bearing methyl and hydroxyl groups as suitable hydrophobic and hydrophilic functionalities respectively, leading to a stable MOF in the aqueous medium. The MOF was used as an adsorbent for selective adsorption of monovalent permanganate anion (MnO4-) over other polyvalent oxo-anions as well as an optical platform for the detection of oxo-anions (permanganate (MnO4-), dichromate (Cr2O72-) and chromate (CrO42-)) and pesticide (2,6-dichloro-4-nitroaniline (2,6-DCNA)) in the aqueous medium. Overall, a combination of luminescent nature and hydrophilic-hydrophobic surface property makes the developed Zn-MOF an interesting platform for environmental application.

Polymethylmethacrylate wettability change spatially correlates with self-organized streamer microdischarge patterns in dielectric barrier discharge plasmas

Multifunctional polymer surfaces exhibiting both hydrophilic and hydrophobic functionality were created using self-organized plasma “streamer” microdischarges occurring in atmospheric pressure dielectric barrier discharges (DBD) operating with argon and air. Surface chemistry and wettability change of polymethylmethacrylate (PMMA) were found to spatially correlate with self-organized streamer patterns. Gas atmosphere was found to play a significant role on streamer density, pattern stability, and lateral contrast of plasma-induced physicochemical property changes across the surface. Stable streamer patterns, with each streamer surrounded by a glowlike discharge, were obtained in argon; discharges in air had more transient and chaotic streamers that were surrounded by dark “plasma free”-like zones. Air plasma streamer treatment of PMMA resulted in hybrid hydrophilic/phobic surfaces with water contact angles (WCA) ranging from 30° to 100° (PMMA WCA = 75°), depending on processing conditions and location. WCA and XPS mapping after treatment revealed that surface chemistry is preferentially modified near streamers, and moreover, that streamer exposure in air locally renders the surface more hydrophilic, surrounded by regions that are more hydrophobic. Overall, this work demonstrates that self-organized streamers in DBD plasmas could be used for scalable and localized modification of surfaces.