10 research outputs found

    Counteranion-Mediated Intrinsic Healing of Poly(ionic liquid) Copolymers

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    Fabrication of self-healing/healable materials using reversible interactions that are governed by their inherent chemical features is highly desirable because it avoids the introduction of extra groups that may present negative effects on their functions. The present study exploits the inherently featured electrostatic interactions of the ion pairs in polymeric ionic liquids (PILs) as the driving force to fabricate healable PIL copolymers. The healable PIL copolymers are fabricated through the copolymerization of the IL monomers with ethyl acrylate followed by the replacement of Br<sup>–</sup> counteranions with bulkier ones such as bis­(trifluoromethanesulfonyl)­imide (TFSI<sup>–</sup>). Without modifying the chemical structures of the PIL moieties, the healing performance of the as-prepared PIL copolymers can be effectively mediated by their counteranions. The PIL copolymers that do not possess healability when paired with Br<sup>–</sup> counteranions become healable after exchanging the Br<sup>–</sup> counteranions with larger-sized ones (e.g., TFSI<sup>–</sup>). The PIL copolymers paired with bulky counteranions exhibit enhanced chain mobility and highly reversible ion-pair interactions, which facilitate the healing process. The PIL copolymers paired with TFSI<sup>–</sup> anions can completely heal the damage/cut upon heating at 55 °C for 7.5 h. Meanwhile, the counteranions with larger sizes not only benefit the healing performance of the PIL copolymers but also enhance their ion conductivity. The ion conductivity of the PIL copolymers paired with TFSI<sup>–</sup> is an order of magnitude higher than that of the PIL copolymers paired with Br<sup>–</sup>. Therefore, the as-prepared healable PIL copolymers are potentially useful as solid electrolytes in PIL-based energy devices to improve their safety and reliability

    Rapid Seeded Growth of Monodisperse, Quasi-Spherical, Citrate-Stabilized Gold Nanoparticles via H<sub>2</sub>O<sub>2</sub> Reduction

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    In this report, we demonstrate a rapid and simple seeded growth method for synthesizing monodisperse, quasi-spherical, citrate-stabilized Au nanoparticles (Au NPs) via H<sub>2</sub>O<sub>2</sub> reduction of HAuCl<sub>4</sub>. Au NPs with diameter ranging from 30 to 230 nm can be synthesized by simply adding 12 nm citrate stabilized Au NP seeds to an aqueous solution of H<sub>2</sub>O<sub>2</sub> and HAuCl<sub>4</sub> under ambient conditions. The diameter of the resulting Au NPs can be quantitatively controlled by the molar ratio of HAuCl<sub>4</sub> to the Au seeds. The standard deviation of the Au NP sizes is less than 10%, and the ellipticity (ratio of major to minor axes) of the NPs is less than 1.1. Compared to existing ones, the present seeded growth approach is implemented within 1 min under ambient condition, and no unfavorable additives are involved because H<sub>2</sub>O<sub>2</sub> can readily decompose into H<sub>2</sub>O during storage or via boiling

    Substrate-Independent, Transparent Oil-Repellent Coatings with Self-Healing and Persistent Easy-Sliding Oil Repellency

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    Herein we report a simple and substrate-independent approach to fabricate transparent oil-repellent coatings, which involves alternate deposition of poly­(diallyl­dimethyl­ammonium) (PDDA) and poly­(styrene­sulfonate) (PSS) onto substrates, followed by incubation of the coated objects into perfluoro­octanoate (PFO) aqueous solutions for 2 min. Various low-surface-tension liquids can easily slide down the coating surfaces on flat substrates at a sliding angle lower than 12° for 10 ÎŒL droplets. The coatings are applicable to different substrates including Si, glass, plastic, steel, and wood, and those with complex shapes and large surface areas. They are also applicable to rough substrates with roughness at both micro/nanoscale and macroscopic scales to realize the easy-sliding oil repellency. Incubation of the PDDA/PSS polyelectrolyte multilayers (PEMs) into PFO solutions induces an effective but nondestructive substitution of PFO anions for PSS in the PEMs, which results in a composite coating with PFO anions homogeneously interspersed in both the coating surface and the bulk. Thanks to the as-described “repeating-layer” composition/structure of the coatings, their easy-sliding oil repellency can be self-healed after surface decomposition or well maintained after physical damages, due to the replenishing surface. Therefore, the advantageous characteristics of the as-developed oil-repellent coatings and the simplicity of the preparation protocol make the coatings highly practical for real-world applications. It is believed that the coatings can perform as antismudge coatings that shield against oil-borne contaminants, chemical-shield coatings that protect coated plastics from dissolution by organic solvents, and nonstick coatings (of oil tankers or pipelines) that enable loss-free oil transportation

    Substrate-Independent, Transparent Oil-Repellent Coatings with Self-Healing and Persistent Easy-Sliding Oil Repellency

    No full text
    Herein we report a simple and substrate-independent approach to fabricate transparent oil-repellent coatings, which involves alternate deposition of poly­(diallyl­dimethyl­ammonium) (PDDA) and poly­(styrene­sulfonate) (PSS) onto substrates, followed by incubation of the coated objects into perfluoro­octanoate (PFO) aqueous solutions for 2 min. Various low-surface-tension liquids can easily slide down the coating surfaces on flat substrates at a sliding angle lower than 12° for 10 ÎŒL droplets. The coatings are applicable to different substrates including Si, glass, plastic, steel, and wood, and those with complex shapes and large surface areas. They are also applicable to rough substrates with roughness at both micro/nanoscale and macroscopic scales to realize the easy-sliding oil repellency. Incubation of the PDDA/PSS polyelectrolyte multilayers (PEMs) into PFO solutions induces an effective but nondestructive substitution of PFO anions for PSS in the PEMs, which results in a composite coating with PFO anions homogeneously interspersed in both the coating surface and the bulk. Thanks to the as-described “repeating-layer” composition/structure of the coatings, their easy-sliding oil repellency can be self-healed after surface decomposition or well maintained after physical damages, due to the replenishing surface. Therefore, the advantageous characteristics of the as-developed oil-repellent coatings and the simplicity of the preparation protocol make the coatings highly practical for real-world applications. It is believed that the coatings can perform as antismudge coatings that shield against oil-borne contaminants, chemical-shield coatings that protect coated plastics from dissolution by organic solvents, and nonstick coatings (of oil tankers or pipelines) that enable loss-free oil transportation

    Substrate-Independent, Transparent Oil-Repellent Coatings with Self-Healing and Persistent Easy-Sliding Oil Repellency

    No full text
    Herein we report a simple and substrate-independent approach to fabricate transparent oil-repellent coatings, which involves alternate deposition of poly­(diallyl­dimethyl­ammonium) (PDDA) and poly­(styrene­sulfonate) (PSS) onto substrates, followed by incubation of the coated objects into perfluoro­octanoate (PFO) aqueous solutions for 2 min. Various low-surface-tension liquids can easily slide down the coating surfaces on flat substrates at a sliding angle lower than 12° for 10 ÎŒL droplets. The coatings are applicable to different substrates including Si, glass, plastic, steel, and wood, and those with complex shapes and large surface areas. They are also applicable to rough substrates with roughness at both micro/nanoscale and macroscopic scales to realize the easy-sliding oil repellency. Incubation of the PDDA/PSS polyelectrolyte multilayers (PEMs) into PFO solutions induces an effective but nondestructive substitution of PFO anions for PSS in the PEMs, which results in a composite coating with PFO anions homogeneously interspersed in both the coating surface and the bulk. Thanks to the as-described “repeating-layer” composition/structure of the coatings, their easy-sliding oil repellency can be self-healed after surface decomposition or well maintained after physical damages, due to the replenishing surface. Therefore, the advantageous characteristics of the as-developed oil-repellent coatings and the simplicity of the preparation protocol make the coatings highly practical for real-world applications. It is believed that the coatings can perform as antismudge coatings that shield against oil-borne contaminants, chemical-shield coatings that protect coated plastics from dissolution by organic solvents, and nonstick coatings (of oil tankers or pipelines) that enable loss-free oil transportation

    Electrostatic Repulsion-Controlled Formation of Polydopamine–Gold Janus Particles

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    Polydopamine (PDA)–Au Janus particles were obtained by simply adding HAuCl<sub>4</sub> to a PDA particle suspension, prepared via self-polymerization of dopamine in basic solution at room temperature. The structures of the PDA–Au particles are readily controlled by electrostatic repulsion between the constituent particles, which can be realized simply via adjusting the environmental pH. PDA–Au Janus particles are formed only in a narrow pH range of 2.5–3.0 due to the properly enhanced electrostatic repulsion between the Au particles growing on as-prepared PDA particles and between the Au and PDA particles. The obtained PDA–Au Janus particles can become interfacially active and self-assemble at oil/water interfaces as a result of spatially well-separated hydrophilic (PDA) and hydrophobic (Au) domains on the surfaces, reminiscent of amphiphilic molecules

    Synthesis of Au and Pt Hollow Capsules with Single Holes via Pickering Emulsion Strategy

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    Au and Pt hollow capsules with single holes were synthesized via a Pickering emulsion strategy. Pickering emulsions provided particles with oil–water interfaces as asymmetric platform for anisotropic structure sculpture. Reactive Cu<sub>2</sub>O particles were utilized not only as emulsifier to prepare Pickering emulsions but also as sacrificed hard template for the consequent asymmetric galvanic reaction at the oil–water interfaces, resulting in the formation of open-mouthed Au and Pt hollow capsules. The opened hollow structure can facilitate the diffusion of reactants to inner side of the shell wall, thus effectively activating the catalytic activity of the inner shell wall of the hollow capsules. The obtained open-mouthed Au hollow capsules show much higher catalytic performance than that of intact Au hollow capsules

    Hierarchical CuO Colloidosomes and Their Structure Enhanced Photothermal Catalytic Activity

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    Hierarchical CuO colloidosomes (hollow spheres) constructed by subunit of open-mouthed hollow spheres that consist of 2D nanoleaves are synthesized via a Pickering emulsion strategy. Cu<sub>2</sub>O particles were served as emulsifier particles to form the Pickering emulsions. Self-oxidation of Cu<sub>2</sub>O gave rise to the formation of CuO nanoleaves which spontaneously cross-link the neighboring particles on the emulsion droplet surfaces, forming the robust colloidosomes. Concurrently, asymmetric Kirkendall effect produced the open-mouthed hollow structure in the subunit CuO particles, resulting in the hierarchical hollow structures of the colloidosomes. Because of the complex and multilevel hollow structure, the CuO colloidosomes significantly enhanced light harvest and photothermal conversion, leading to high local temperature (∌200 °C) on the surfaces under light irradiation at room temperature. This structure enhanced photothermal effect realized the photothermal catalytic CO oxidation at room temperature with a reaction rate 20 times higher than that of thermal catalysis at 240 °C

    Octadecyltrichlorosilane Deposition on Mica Surfaces: Insights into the Interface Interaction Mechanism

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    Surface functionalization by alkylsilanes has been widely used in many engineering applications. In this work, a systematic investigation was conducted on the deposition behaviors of octadecyltrichlorosilane (OTCS) on freshly cleaved mica surfaces that possess a low density of reactive sites (i.e., silanol groups) by a vapor-deposition method. The deposition of OTCS molecules on mica was found to follow a two-stage process, as monitored by measuring the surface morphology using an atomic force microscope and wettability of the samples obtained at different deposition times. The contact mechanics behaviors and interaction forces of the as-obtained OTCS surfaces were characterized using a surface forces apparatus. The contact mechanics tests demonstrate that the OTCS coatings can significantly reduce the surface adhesion and adhesion hysteresis in air. The force–distance profiles of the OTCS surfaces obtained via a shorter deposition time (e.g., 2, 8 h) in aqueous solutions could be reasonably described by the classical Derjaguin–Landau–Verwey–Overbeek theory. However, for the OTCS surfaces obtained by longer deposition times (e.g., 48 h), hydrophobic interaction and steric interaction play an important role due to the enhanced surface hydrophobicity and roughness. Our results provide useful insights into the physicochemical characteristics of alkylsilane deposition and the surface interaction mechanisms of deposited alkylsilanes at solid–air and solid–water interfaces

    Transparent, Healable Elastomers with High Mechanical Strength and Elasticity Derived from Hydrogen-Bonded Polymer Complexes

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    It is challenging to develop healable elastomers with combined high mechanical strength and good elasticity. Herein, a simple strategy to develop high-performance elastomers that integrate high mechanical strength, enormous stretchability, good resilience, and healability is reported. Through simply complexing poly­(acrylic acid) and poly­(ethylene oxide) based on hydrogen-bonding interactions, transparent composite materials that perform as elastomers are generated. The as-prepared elastomers exhibit mechanical strength (true strength at break) and toughness (fracture energy) as high as 61 MPa and 22.9 kJ/m<sup>2</sup>, respectively, and they can be stretched to >35 times their initial length and are able to return to their original dimensions following the removal of stress. Further, the elastomers are capable of healing from physical cuts/damages in a humid environment because of reformation of the reversible hydrogen bonds between the polymer components. The high mechanical strength of the elastomers is ascribed to the high degree of polymer chain entanglements and multiple hydrogen-bonding interactions in the composites. The reversible hydrogen bonds, which act as cross-linkages, facilitate the unfolding and sliding of the polymer chains in the composites, thereby endowing the elastomers with good elasticity and healability. Furthermore, flexible conductors with water-enabled healability were developed by drop-casting Ag nanowires on top of the elastomers
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