Polyurethane Based Smart Composite Fabric for Personal Thermal Management in Multi-Mode.

Textiles with thermal/moisture managing functions are of high interest. However, making the textile sensitive to the surrounding environment is still challenging. Herein, a multimodal smart fabric is developed by stitching together the Ag coated thermal-humidity sensitive thermoplastic polyurethane (Ag-THSPU) and the hybrid of polyvinylidene fluoride and polyurethane (PU-PVDF). The porous PU-PVDF layer is used for solar reflection, infrared emissivity, and water resistance. The Ag-THSPU layer is designed for regulating thermal reflection, sweat evaporation as well as convection. In cold and dry state, the Ag domains are densely packed covering the crystalline polyurethane matrix, featuring low water transmission (102.74 g m-2·24 h-1), high thermal reflection and 2.4 °C warmer than with cotton fabric. In the hot and humid state, the THSPU layer is swollen by sweat and expands in area, resulting in the formation of micro-hook faces where the Ag domains spread apart to promote sweat evaporation (2084.88 g/m-2·24 h-1), thermal radiation and convection, offering 2.5 °C cooler than with cotton fabric. The strategy reported here opens a new door for the development of adaptive textiles in demanding situations.

Self-Forming Interlocking Interfaces on the Immiscible Polymer Bilayers via Gelation-Mediated Phase Separation.

Gelation-mediated phase separation is applied to prepare immiscible polymer bilayer films with an interlocking interface structure. Polymer systems consisting of copolymer of urea and polydimethylsiloxane and epoxy are selected to demonstrate the feasibility. When the epoxy fraction exceeds 25 wt%, well-defined bilayer structures self-form by a one-pot casting method in which the phase separation state is fixed by an evaporation-induced gelation. Microscopy studies of the resulting bilayers clearly reveal that interlocking structures form during the bilayer films construct. The interlocking structures lead to an enhanced interfacial adhesion and higher fracture energy. The current strategy might offer a facile way to in situ create an interlocking interface between immiscible polymer systems.

Controlling the Localization of Liquid Droplets in Polymer Matrices by Evaporative Lithography.

Localized inclusions of liquids provide solid materials with many functions, such as self-healing, secretion, and tunable mechanical properties, in a spatially controlled mode. However, a strategy to control the distribution of liquid droplets in solid matrices directly obtained from a homogeneous solution has not been reported thus far. Herein, we describe an approach to selectively localize liquid droplets in a supramolecular gel directly obtained from its solution by using evaporative lithography. In this process, the formation of droplet-embedded domains occurs in regions of free evaporation where the non-volatile liquid is concentrated and undergoes a phase separation to create liquid droplets prior to gelation, while a homogeneous gel matrix is formed in the regions of hindered evaporation. The different regions of a coating with droplet embedment patterns display different secretion abilities, enabling the control of the directional movement of water droplets.

Solvent-Induced Facile Synthesis of Cubic-, Spherical-, and Honeycomb-Shape Palladium N-Heterocyclic Carbene Particles and Catalytic Applications in Cyanosilylation.

The facile synthesis of palladium N-heterocyclic carbene (NHC) particles with spherical, cubic, and honeycomb morphologies is accomplished. The structures of cubic and honeycomb particles are defined as an unprecedented trinuclear palladium-NHC complex. An obvious effect of particle morphologies on catalytic activity and recyclability is observed in hetero-geneous cyanosilylation.

Anion-directed assemblies of cationic metal-organic frameworks based on 4,4'-bis(1,2,4-triazole): syntheses, structures, luminescent and anion exchange properties.

Three cationic metal-organic frameworks (MOFs), Ag(btr)·PF6·0.5CH3CN (1), Ag2(btr)2(H2O)·2CF3SO3·H2O (2), and Ag2(btr)2(NO3)·NO3 (3), were prepared from reaction of 4,4'-bis(1,2,4-triazole) (btr) with silver salts containing different anions. Complex 1 is a three-dimensional (3-D) framework constructed from tetrahedral-shaped nanoscale coordination cages with PF6(-) as counteranions. 2 and 3 are 3-D architectures containing 1-D channels, in which charge-balancing CF3SO3(-) and NO3(-) are located in their respective channels. Luminescent emission of 1-3 shows an obvious red shift compared with the btr ligand. Anion exchange studies show that 1 is able to selectively exchange MnO4(-) in aqueous solution with a modest capacity of 0.56 mol mol(-1); the luminescent emission of 1 is quickly quenched upon MnO4(-) exchange.

Eco-Friendly Fabrication of Highly Stable Silica Aerogel Microspheres with Core-Shell Structure.

Silica aerogel microspheres show great potential in various fields as fillings in different materials. It is important to diversify and optimize the fabrication methodology for silica aerogel microspheres (SAMS). This paper presents an eco-friendly synthetic technique for producing functional silica aerogel microspheres with a core-shell structure. Mixing silica sol with commercial silicone oil containing olefin polydimethylsiloxane (PDMS) resulted in a homogeneous emulsion with silica sol droplets dispersed in the oil. After gelation, the droplets were transformed into silica hydrogel or alcogel microspheres and coated with the polymerization of the olefin groups. Microspheres with silica aerogel as their core and polydimethylsiloxane as their shell were obtained after separation and drying. The sphere size distribution was regulated by controlling the emulsion process. The surface hydrophobicity was enhanced by grafting methyl groups onto the shell. The obtained silica aerogel microspheres have low thermal conductivity, high hydrophobicity, and excellent stability. The synthetic technique reported here is expected to be beneficial for the development of highly robust silica aerogel material.

Water-actuated reversible shape-memory polydimethylsiloxane for potential biomedical applications.

Shape memory polymers (SMPs) show great potential in biomedical fields. However, most of the SMPs are not suitable for use in the human body due to their deleteriousness and harsh actuation conditions. It is important to diversify SMPs that could be actuated in the human body environment. Herein, we construct a reversible shape-memory polydimethylsiloxane (RSMPDMS) based on a feasible strategy by deposing the PDMS-salt layer with dynamic micro-creases on the pure PDMS layer. Testing results reveal that it equips with self-expanding, bio-compatibility, drug storage-release and good mechanical toughness. The RSMPDMS could be variously shaped, such as ring, coil, and spiral. The prepared samples present efficient deformation-recovery with high mechanical stability during water absorption-desorption cycles. Moreover, the RSMPDMS is confirmed biocompatible by cell viability analysis and cell fluorescent labeling method, accompanied with efficient drug storage-release. The novel-designed RSMPDMS may contribute to the development of new shape memory biomedical materials.

Pruney Finger-Inspired Switchable Surface with Water-Actuated Dynamic Textures.

Switchable surfaces play an important role in the development of functional materials. However, the construction of dynamic surface textures remains challenging due to the complicated structural design and surface patterning. Herein, a pruney finger-inspired switchable surface (PFISS) is developed by constructing water-sensitive surface textures on a polydimethylsiloxane substrate by taking advantage of the hygroscopicity of the inorganic salt filler and the 3D printing technology. Like human fingertips, the PFISS shows high water sensitivity with obvious surface variation in wet and dry states, which is actuated by water absorption-desorption of the hydrotropic inorganic salt filler. Besides, when the fluorescent dye is optionally added into the matrix of the surface texture, water-responsive fluorescent emitting is observed, providing a feasible surface-tracing strategy. The PFISS shows effective regulation of the surface friction and performs a good antislip effect. The reported synthetic strategy for the PFISS offers a facile way for building a wide range of switchable surfaces.

Post-synthetic modification (PSM) of MOFs with an ionic polymer for efficient adsorptive removal of methylene blue from water.

UiO-66-NH2 was functionalized with an ionic polymer poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS) through a post-synthetic modification (PSM) strategy. Due to the excellent dispersibility in water and the existence of abundant active binding sites, the obtained UiO-66-PAMPS shows significantly improved adsorption capability toward methylene blue (MB) in aqueous solution.

Engineering sodium alginate-SiO2 composite beads for efficient removal of methylene blue from water.

The lack of sufficient active binding sites in commonly reported sodium alginate (SA)-based porous beads hampers their performances in adsorption of water contaminants. To address this problem, porous SA-SiO2 beads functionalized with poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS) are reported in this work. Due to the porous properties and the existence of abundant sulfonate groups, the obtained composite material SA-SiO2-PAMPS shows excellent adsorption capacity toward cationic dye methylene blue (MB). The adsorption kinetic and adsorption isotherm studies reveal that the adsorption process fits closely to pseudo-second-order kinetic model and Langmuir isotherm model, respectively, suggesting the existence of chemical adsorption and monolayer adsorption behavior. The maximum adsorption capacity obtained from Langmuir model is found to be 427.36, 495.05, and 564.97 mg/g under 25, 35, and 45 °C, respectively. The calculated thermodynamic parameters indicate that MB adsorption on SA-SiO2-PAMPS is spontaneous and endothermic.

Switchable Cavitation in Silicone Coatings for Energy-Saving Cooling and Heating.

Space cooling and heating currently result in huge amounts of energy consumption and various environmental problems. Herein, a switching strategy is described for efficient energy-saving cooling and heating based on the dynamic cavitation of silicone coatings that can be reversibly and continuously tuned from a highly porous state to a transparent solid. In the porous state, the coatings can achieve efficient solar reflection (93%) and long-wave infrared emission (94%) to induce a subambient temperature drop of about 5 °C in hot weather (≈35 °C). In the transparent solid state, the coatings allow active sunlight permeation (95%) to induce solar heating to raise the ambient temperature from 10 to 28 °C in cold weather. The coatings are made from commercially available, cheap materials via a facile, environmentally friendly method, and are durable, reversible, and patternable. They can be applied immediately to various existed objects including rigid substrates.

Earthworm-Inspired Rough Polymer Coatings with Self-Replenishing Lubrication for Adaptive Friction-Reduction and Antifouling Surfaces.

Earthworms are able to pass through sticky soil without inducing stains through a self-forming thick lubricating layer on their rough skins. To mimic this earthworm-like lubricating capability, an attempt to create a textured structure on the surface of liquid-releasable polymer coatings by a "breath figure" process is described herein. The resulting coatings exhibit fast and site-specific release behavior under external triggers such as solid-based friction. The released oil is then stabilized by the surface texture to form thick lubricating layers, reducing friction and enhancing wear resistance. Moreover, the coatings also exhibit excellent antifouling property in a sticky soil environment. Because the lubricating layer can be regenerated after consumption, the potential of this self-replenished lubricating mechanism in preparing friction-reduction, antiwear, and antifouling coatings used in solid-based environments is therefore envisioned.

Thermoresponsive Mobile Interfaces with Switchable Wettability, Optical Properties, and Penetrability.

Liquid-based mobile interfaces, in which liquids are being utilized as structural long-term components, have shown their multifunctionality in materials science, such as the hydration layer of polyelectrolyte brushes used for artificial implants, stabilized lubricants for antibiofouling, anti-icing, self-cleaning, optical control, and so forth. However, these currently available systems do not usually show a response to environmental stimuli. Here, we describe a strategy for preparing thermoresponsive mobile interfaces made from novel silicone-based lubricants that display lower critical solution temperature and demonstrate their capabilities on controlling in situ water wetting and dewetting, thermo-gating penetration, and optical properties. These properties allow the mobile films to form a kind of erasable recording platforms. We foresee diverse applications in liquid transport, wetting and adhesion control, and transport switching.

Spherical core-shell magnetic particles constructed by main-chain palladium N-heterocyclic carbenes.

The encapsulation of the functional species on magnetic core is a facile approach for the synthesis of core-shell magnetic materials, and surface encapsulating matrices play crucial roles in regulating their properties and applications. In this study, two core-shell palladium N-heterocyclic carbene (NHC) particles (Fe3O4@PNP1 and Fe3O4@PNP2) were prepared by a one-pot reaction of semi-rigid tripodal imidazolium salts and palladium acetate in the presence of magnetite nanoparticles. The magnetite nanoparticles are encapsulated inside the main-chain palladium, which act as cores. The conjugated effects of triphenyltriazine and triphenylbenzene in the imidazolium salts have important influence on their physical properties and catalytic performances. Fe3O4@PNP2 shows better recyclability than Fe3O4@PNP1. Unexpectedly, Pd(ii) is well maintained after six consecutive catalytic runs in Fe3O4@PNP2, and Pd(0) and Pd(ii) coexist in Fe3O4@PNP1 under the same conditions; moreover, the morphologies of these spherical core-shell particles show no significant variation after six consecutive catalytic runs.

In situ formation of well-dispersed palladium nanoparticles immobilized in imidazolium-based organic ionic polymers.

A new strategy for in situ generation of well-dispersed palladium nanoparticles (NPs) immobilized in imidazolium-based organic ionic polymers was presented. Without extra addition of palladium species, the as-synthesized ionic polymers showed excellent catalytic activity and good reusability in the hydrogenation of nitroarenes.

Facile fabrication of ultrafine palladium nanoparticles with size- and location-control in click-based porous organic polymers.

Two click-based porous organic polymers (CPP-1 and CPP-2) are readily synthesized through a click reaction. Using CPP-1 and CPP-2 as supports, palladium nanoparticles (NPs) with uniform and dual distributions were prepared through H2 and NaBH4 reduction routes, respectively. Ultrafine palladium NPs are effectively immobilized in the interior cavities of polymers. The coordination of 1,2,3-triazolyl to palladium and the confinement effect of polymers on palladium NPs are verified by solid-state (13)C NMR and IR spectra, XPS analyses, EDX mapping, and computational calculation. The steric and electronic properties of polymers have a considerable influence on the interaction between polymers and palladium NPs, as well as the catalytic performances of NPs. The ultrafine palladium NPs with uniform distribution exhibit superior stability and recyclability over palladium NPs with dual distributions and palladium on charcoal in the hydrogenation of nitroarenes, and no obvious agglomeration and loss of catalytic activity were observed after recycling several times. The excellent performances mainly result from synergetic effects between palladium NPs and polymers.

Shape-controllable formation of poly-imidazolium salts for stable palladium N-heterocyclic carbene polymers.

The imidazolium-based main-chain organic polymers are one of promising platforms in heterogeneous catalysis, the size and outer morphology of polymer particles are known to have important effects on their physical properties and catalytic applications, but main-chain ionic polymers usually generate amorphous or spherical particles. Herein, we presented a versatile and facile synthetic route for size- and shape-controllable synthesis of main-chain poly-imidazolium particles. The wire-shaped, spherical and ribbon-shaped morphologies of poly-imidazolium particles were readily synthesized through quaternization of bis-(imidazol-1-yl)methane and 2,4,6-tris(4-(bromomethyl)phenyl)-1,3,5-triazine, and the modification of their size and morphology were realized through adjusting solvent polarity, solubility, concentration and temperatures. The direct complexation of the particles with Pd(OAc)2 produced ionic polymers containing palladium N-heterocyclic carbene units (NHCs) with intactness of original morphologies. The particle morphologies have a significant effect on catalytic performances. Wire-shaped palladium-NHC polymer shows excellent catalytic activity and recyclabilty in heterogeneous Suzuki-Miyaura cross-coupling reaction.

Synthesis and Crystal Structures of Coordination Complexes Containing Cu2 I2 Units and Their Application in Luminescence and Catalysis.

The reaction of bis- or tris-chelating nitrogen-containing ligands (L1-L5) with CuI gave rise to five coordination complexes consisting of Cu2 I2 dimeric units. L1 in complex 1 adopts a cis conformation and links Cu2 I2 into a dinuclear structure. L2 and L3 in complexes 2 and 3 exhibit a trans conformation, and the alternative linkage of L2 or L3 and Cu2 I2 results in the formation of a 1D chain. In complex 4, two pyrazolyl-pyridine units of L4 at the same side of the central phenyl ring are connected to Cu2 I2 forming a tetranuclear macrocycle, and the third pyrazolyl-pyridine unit at the other side of the central phenyl ring further links the macrocycle into a 1D chain. L5 bridges Cu2 I2 in a cis conformation forming a tetranuclear complex, which is very different from 1 owing to the difference of the electronic property between pyrazolyl and triazolyl rings. The coordination nitrogen atoms in two pairs of ortho-positioned nitrogen-containing chelating rings in L1 and L5 are directed toward opposite and the same directions, respectively. Complexes 1-4 containing pyrazolyl-pyridine units showed luminescence whereas no clear emission was observed in complex 5 containing triazolyl-pyridine units, despite the fact that they were investigated under the same conditions. The application of complexes 1-5 in the copper(I)-catalyzed Ullmann cross-coupling reaction and azide-alkyne cycloaddition reaction was preliminarily evaluated.