Fouling caused by oil and other pollutants is one of the most serious challenges for membranes used for oil/water separation. Aiming at improving the comprehensive antifouling property of membranes and thus achieving long-term cyclic stability, it is reported in this work the design of a kind of zwitterionic nanosized hydrogels grafted poly(vinylidene fluoride) (PVDF) microfiltration membrane (ZNG-g-PVDF) with superior fouling-tolerant property for oil-in-water emulsion separation. Sulfobetaine zwitterionic nanohydrogels with the diameter of ≈50 nm are synthesized by an inverse microemulsion polymerization process. They are then grafted onto the surface of PVDF microfiltration membrane, endowing the membrane a superhydrophilic and nearly zero oil adhesion property. This ZNG-g-PVDF membrane exhibits great tolerance and resistance to salts pH, especially an excellent antifouling property to oil-in-water emulsions containing various pollutants such as surfactants, proteins, and natural organic materials (e.g., humic acid). The comprehensive antifouling property of the membrane gives rise to the cyclic stability of the membrane greatly improved. A nearly 100% recovery ratio of permeating flux is achieved during several cycles of oil-in-water emulsion filtration. The ZNG-g-PVDF membrane shows great potential in treating practical oily wastewater containing complicated components in the effluent.

In this paper, highly stable violet-blue emitting ZnSe/ZnS core/shell QDs have been synthesized by a novel "low temperature injection and high temperature growth" method. The resulting nearly monodisperse ZnSe/ZnS core/shell QDs exhibit excellent characteristics such as a high color saturation (typical spectral full width at half-maximum between 12 and 20 nm), good emission tunability in the violet-blue range of wavelengths from 400 to 455 nm, a high absolute PL quantum yield (up to 83%), and superior chemical and photochemical stability. By employing ZnSe/ZnS core/shell quantum dots (QDs) as emitters with a fully solution processable method, bright, efficient, and color-stable violet Cd-free quantum dot-based light-emitting diodes (QD-LEDs) with maximum luminance up to 2632 cd m(-2) and a peak EQE of 7.83% have been demonstrated successfully. Considering the factors of the photopic luminosity function, the brightness and efficiency results of such violet QD-LEDs not only represent a 12-fold increase in device efficiency and an extraordinary 100 times increase in luminance compared with previous Cd-free QD-LEDs but also can be much superior to the best performance (1.7%) of their Cd-based violet counterparts. These results demonstrate significant progress in short-wavelength QD-LEDs and shed light on the acceleration of commercial application of environmentally-friendly violet QD-based displays and lighting.

High‐quality violet‐blue emitting ZnxCd1‐xS/ZnS core/shell quantum dots (QDs) are synthesized by a new method, called “nucleation at low temperature/shell growth at high temperature”. The resulting nearly monodisperse ZnxCd1‐xS/ZnS core/shell QDs have high PL quantum yield (near to 100%), high color purity (FWHM) <25 nm), good color tunability in the violet‐blue optical window from 400 to 470 nm, and good chemical/photochemical stability. More importantly, the new well‐established protocols are easy to apply to large‐scale synthesis; around 37 g ZnxCd1‐xS/ZnS core/shell QDs can be easily synthesized in one batch reaction. Highly efficient deep‐blue quantum dot‐based light‐emitting diodes (QD‐LEDs) are demonstrated by employing the ZnxCd1‐xS/ZnS core/shell QDs as emitters. The bright and efficient QD‐LEDs show a maximum luminance up to 4100 cd m−2, and peak external quantum efficiency (EQE) of 3.8%, corresponding to 1.13 cd A−1 in luminous efficiency. Such high value of the peak EQE can be comparable with OLED technology. These results signify a remarkable progress, not only in the synthesis of high‐quality QDs but also in QD‐LEDs that offer a practicle platform for the realization of QD‐based violet‐blue display and lighting.

Oil fouling threatens the water flux stability of membranes for oil/water separation. Simple hydrophilic modification fights for an opportunity to prevent oil contamination but fails to eliminate severe water flux decline. In essence, a “single‐defense” mechanism is insufficient to build a potent barrier against accumulated cake layer under a filtration environment. This work reports a “double‐defense” design by integrating hydrophilic polymer brushes and hydrogel layer on oil/water separation membranes for desired anti‐oil‐fouling property, where a poly(vinylidene fluoride) porous membrane is first covered by a layer of poly(hydroxyethyl methylacrylate) hydrogel and then controllably grafted with poly(sulfobetaine) brushes. The spatially hierarchical structure establishes a highly covered “double‐defense” barrier for the membrane surface to efficiently repel oil adhesion and the formation of an accumulated cake layer. When separating various surfactant‐stabilized oil‐in‐water emulsions, the permeating flux displays a nearly zero decline throughout the whole filtration period. Most importantly, the permeating flux of the membrane is almost the same when filtrating pure water and filtrating oil‐in‐water emulsions, which is difficult to be achieved by the general membranes, indicating that the membrane has excellent anti‐oil‐fouling property superior to the currently reported membranes.

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Extracting light from quantum dot light emitting diodes (QLEDs) by applying optical-functional nanostructures inside and outside the devices is essential for their commercial application in illumination and displays. In this paper, we demonstrate the highly effective extraction of waveguided light from the active region of QLEDs by embedding internal grating patterns fabricated using a nanoimprint lithography technique. The grating couples out waveguide mode power into the substrate without changing the device's electrical properties, resulting in an increase in both the external quantum efficiency and luminous efficiency for a green QLED from 11.13% to 13.45%, and 29 010 cd m-2 to 44 150 cd m-2, respectively. The observed improvement can be ascribed to the elimination of the waveguide mode by the grating nanostructures introduced in the device. Furthermore, the finite-difference time-domain (FDTD) simulation also demonstrated that the power loss due to the waveguide mode was reversed. The results indicate that internal nano-scattering pattern structures are attractive for enhancing the out-coupling efficiency of QLEDs.

Hydrogels are excellent for protecting membranes from oil fouling for oil/water separation. However, conventional hydrogels including adhesive hydrogels have a contradictory between high adhesion on membranes and anti‐oil‐fouling ability. Herein, the design of an adhesive hydrogel on membranes is proposed by ingeniously integrating high adhesion on membranes, outstanding anti‐oil‐fouling ability, ultrathin thickness suitable for membrane decoration and satisfactory durability, where an inside‐out gradient distribution of adhesive protocatechuic acid (PCA) and hydrated calcium alginate (CaAlg) on membranes is constructed. The innermost PCA enables the adhesive hydrogel to tightly adhere to the membranes. The outermost CaAlg defends membranes from oil fouling. The gradient distribution and uniform integration of PCA/CaAlg guarantee an excellent stability. Membranes decorated with the adhesive hydrogel demonstrate superhydrophilicity,  anti‐fouling to various oils, and anti‐abrasion to external damaging. The membranes achieve ultra‐stable and efficient separation of surfactant‐stabilized oil‐in‐water emulsions and crude oil/water mixture with the most advanced cycling ability of ≈100% flux recovery and nearly zero irreversible oil fouling. This study provides a new strategy for designing anti‐oil‐fouling membranes toward practical oil/water separation applications.

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