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Superhydrophobic surfaces hold great prospects for extremely diverse applications owing to their water repellence property. The essential feature of superhydrophobicity is micro-/nano-scopic roughness to reserve a large portion of air under a liquid drop. However, the vulnerability of the delicate surface textures significantly impedes the practical applications of superhydrophobic surfaces. Robust superhydrophobicity is a must to meet the rigorous industrial requirements and standards for commercial products. In recent years, major advancements have been made in elucidating the mechanisms of wetting transitions, design strategies and fabrication techniques of superhydrophobicity. This review will first introduce the mechanisms of wetting transitions, including the thermodynamic stability of the Cassie state and its breakdown conditions. Then we highlight the development, current status and future prospects of robust superhydrophobicity, including characterization, design strategies and fabrication techniques. In particular, design strategies, which are classified into passive resistance and active regeneration for the first time, are proposed and discussed extensively.

Water droplets are usually charged positively via either electrospray or contact electrification at the solid/liquid interface. Herein, we describe a facile two-step strategy to generate charged droplets with desired polarities. In particular, negatively charged droplets can be generated via electrostatic induction using a precharged superamphiphobic substrate as an electret. The interplay of repulsive and attractive interactions between like- and unlike-charged droplets or electret leads to rapid droplet transport and self-assembly of specific highly ordered arrays.

Polymer coatings with comprehensive properties including passive radiative cooling, anti-fouling, and self-healing constitute a promising energy-saving strategy but have not been well documented yet. Herein, we reported a class of novel multifunctional supramolecular polysiloxane composite coatings showing the combination of these features. The coatings have a hybrid structure with a slippery liquid-infused porous surface and a gradient polymer-Al

Water evaporation-driven electricity (EDE) has attracted a great deal of attention in recent years as a novel renewable energy. Previous works have demonstrated that a high evaporation rate leads to a large output voltage. Hence, it is believed that heating is beneficial to EDE by enhancing the evaporation rate. However, experimental verification is lacking. This study demonstrates that heat induces a thermodiffusion effect that drives hydrated ions in the opposite direction of the evaporation-driven water flow, which reduces the output voltage as a synergistic effect. Our findings could be useful for designing a multifunction EDE generator and provide insight into the electricity generation mechanism.

In-fiber fluid instability can be harnessed to realize scalable microparticles fabrication with tunable sizes and multifunctional characteristics making it competitive in comparison to conventional microparticles fabrication methods. However, since in-fiber fluid instability has to be induced via thermal annealing and the resulting microparticles can only be collected after dissolving the fiber cladding, obtaining contamination-free particles for high-temperature incompatible materials remains great challenge. Herein, confinement-free fluid instability is demonstrated to fabricate polymeric microparticles in a facile manner induced by the ultralow surface energy of the superamphiphobic surface. The polymer solution columns break up into uniform droplets then form spherical particles spontaneously in seconds at ambient temperature. This method can be applied to a variety of polymers spanning an exceptionally wide range of sizes: from 1 mm down to 1 µm. With the aid of microfluidic spinning instrument, a large quantity of microparticles can be obtained, making this method promising for scaling up production. Notably, through simple modification of the feed solution configuration, composite/structured micromaterials can also be produced, including quantum-dots-labeled fluorescent particles, magnetic particles, core-shell particles, microcapsules, and necklace-like microfibers. This method, with general applicability and facile control, is envisioned to have great prospects in the field of polymer microprocessing.

In this work, poly(arylene ether nitrile) (PEN) was utilized to fabricate a separation membrane to remove dye molecules and oil/water emulsions for the very first time. Specifically, 15 wt% polyethylene glycol ([Formula: see text] = 800 Da) was added to the casting solution as a pore-forming agent to enhance the flux. In situ-generated SiO2 nanoparticles (NPs) were utilized to improve the membrane surface hydrophilicity by the hydrolyzation of tetraethyl orthosilicate under weak acid conditions. However, the surface hydrophilicity improvement was not significant. It may be because the strong mechanical strength of PEN caused most of the SiO2 NPs to be buried within the polymer matrix or SiO2 NPs were lost by dissolution in the acidic water bath. Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy were performed to study the membrane surface chemical features. Scanning electron microscopy images were obtained to observe the membrane cross-section morphology.

Excessive level of heavy metals results in serious health and environmental issues. Therefore, an efficient and real-time detection of trace amount of heavy metals is indispensable. In this work, mixed matrix membranes (MMMs) are fabricated via a simple priming method. The surface and cross-section morphology of MMMs are investigated by scanning electron microscope (SEM) to rule out those MOFs particles, which are blended with sulfonated poly (arylene ether nitrile) (SPEN). Thus MMMs without serious agglomeration are obtained. The MMMs incorporated with different proportions of MOF-5 are successfully used for sensitively and selectively detecting the heavy metal ions. The results reveal that the heavy metals with the concentration of 10−6 M still can efficiently quench the fluorescence of MMMs. In addition, the presented results further verify that the trace amount of Cu2+ can be sensed by MMMs with little interference from other competing analogues, including Hg2+, Co2+, Cd2+, and Pb2+.

In this work, two different functionalized graphene oxide (GO), sulfonic acid functionalized GO (SGO) and amino functionalized GO (NGO), were synthesized and incorporated into the sulfonated poly(arylene ether nitrile) (SPEN) by single doping and codoping. It was found that the codoping of SGO and NGO contributed to the enhancement of proton exchange membrane performance. These two functionalized GO as fillers were uniformly dispersed in SPEN matrix and their synergistic effect created the long-range proton transfer channels along fillers/SPEN matrix interfaces. Meanwhile, acid-base pairs which was induced by strong interfacial interactions between fillers and SPEN matrix provided new and low-energy-barrier pathways for proton hopping, facilitating the proton conduction via Grotthuss mechanism. Among all the membranes, the codoped S/N-3 composite membrane exhibited the highest proton conductivity (0.064 S·cm−1 at 20 °C and 0.21 S·cm−1 at 80 °C). Besides, it was endowed with unprecedented dimensional stability, especially in high temperature (just 12.75% at 80 °C). Also, low methanol permeability was conferred owing to methanol trapping effect of two functionalized GO. Furthermore, S/N-3 composite membrane showed a superior selectivity of 4.48 × 105S⋅cm−3⋅s, which was nearly 10 times of that of commercialized Nafion 117. Our investigation provides a new strategy on the design of high performance composite membranes for applications of PEMs and other related fields.

When external pressure drives an electrolyte solution in a capillary tube with a charged inner surface, we obtain a streaming potential/current. This effect is also manifested when water flows through the microchannels of a tree, which is driven by capillary pressure and natural evaporation. Thus, by making use of natural evaporation, we took advantage of the anisotropic three-dimensional wood structures to fabricate nanogenerators drawing electricity from the streaming potential/current. As a result, direct current can be harvested continuously, simply through a piece of wood. A 300 mV open-circuit voltage and a 10 μA short-circuit current (ISC) were recorded from a single device, which surpassed the ISC values of most previous works by an order. By connecting five wood nanogenerators in series, a calculator can be completely functional, as a demonstration for practical application.

We show that it is possible to assemble a sparse mono-layer of Fe3O4 nanoparticles (NPs) at cathode interface of a polymer solar cell based on poly(3-hexylthiophene): [6,6]-phenyl-C60-butyric acid methyl ester (P3HT: PCBM) through the synergic effect of strong convective outflow, surface energy, Fe3O4 NPs concentration and active layer thickness. When the distance between those Fe3O4 NPs is smaller than the size of P3HT, the P3HT is excluded from the inter-particle space, and fullerene molecules fill in the space to build electron transport pathways improving charge transport and collection near cathode interface proved by transmission electron microscopy and X-ray photoelectron spectroscopy. The power conversion efficiency of the devices is improved up to 20%. The bulk morphology of light absorbing layers is not affected by the addition of Fe3O4 NPs as demonstrated by neutron and X-ray scattering results.

Phenyl-C71-butyric acid methyl ester (PC71BM) could intercalate between the side-chains of poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene (pBTTT) creating a stable co-crystal structure, so optimal solar cell performance was obtained at high PC71BM concentrations promoting phase separated electron conductive pathways. Neutron reflectivity, with the application of magnetic contrast variation, was used to investigate the concentration profile of PC71BM within the active layer. And this profile was found to be homogeneous through the film thickness. Small angle neutron scattering was utilized to find there is amorphous PC71BM even at 50 wt% of fullerene while previously it was believed that all fullerene was consumed to form co-crystals when its concentration is below 75 wt%. These fullerene molecules evolve into approximately 15 nm sized agglomerates to improve the electron transport when their concentration is above 75 wt%. Thermal annealing gives these agglomerates mobility to form micrometer sized crystals causing a decrease of device performance. These findings can therefore correlate the morphology, especially in terms of fullerene agglomerates, vertical concentration profile and percolating structure they formed, with the device performance and provide valuable guidance for optimal morphology design of polymer: fullerene solar cells.

Our previous study presented up to 20% power conversion efficiency (PCE) enhancement of poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) solar cells under the Fe3O4 nanoparticles (NPs) self-assembly (SA) effect by spin coating. Fe3O4 NPs (about 11 nm hydrodynamic diameter) form a thin layer at the top interface of the light absorbing active layer, which results in the generation of PCBM rich region improving the charge transport (Zhang et al. Sol Energ Mat Sol C 160:126–133, 2017). In order to investigate the feasibility of this Fe3O4 NPs SA effect under large-scale production condition, a smooth rod was implemented to mimic roll-to-roll coating technique and yield active layers having about the same thickness as the spin-coated ones. Small angle neutron scattering and grazing incidence X-ray diffraction were employed finding out similar morphologies of the active layers by these two coating techniques. However, rod-coated solar cell’s PCE decreases with the addition of Fe3O4 NPs compared with the one without them. This is because PCBM rich region is not created at the top interface of the active layer due to the absence of Fe3O4 NPs, which is attributed to the weak convective flow and low diffusion rate. Moreover, in the rod-coated solar cells, the presence of Fe3O4 NPs causes decrease in P3HT crystallinity, thus the charge transport and the device performance. Our study confirms the role of spin coating in the Fe3O4 NPs SA effect and enables researchers to explore this finding in other polymer nanocomposite systems.

We present a dual length morphological model for the active layer of bulk-heterojunction, polymer-based solar cells using results from neutron and X-ray scattering techniques. Two critical characteristic lengths are found in the mixtures composed of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). A characteristic length at 15 nm is the local characteristic of the P3HT crystals and PCBM agglomerations, which is independent of the bulk composition upon relaxation by thermal annealing. Conversely, a larger bicontinuous structure described by Teubner–Strey model with phase distances between 23 and 35 nm forms only after thermal annealing, which is highly correlated to the bulk compositions. These results suggest phase separation between the polymer and fullerene can only be partially manipulated by simple processing techniques such as coating conditions and annealing, and a more rigorous design of the morphology should be implemented in the future. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym. Phys. 2014, 52, 387–396