Miniaturized high signal-to-noise ratio optical air data system using a compact multi-axis parallel transceiver for airborne application.

We have developed a miniaturized multi-channel parallel optical air data system with high signal-to-noise ratio for airborne application. In the system, we designed a fiber amplifier with multi-channel high-energy output that was respectively used as the transmitting signals and a compact multi-axis transceiver with an entrance pupil diameter of 70 mm that was used to receive multi-channel signals simultaneously. We demonstrated the performance of our system both on ground and on board. On ground, the measured line-of-sight speed had an average error of 0.02 m/s and a standard deviation of 0.15 m/s. On board, the standard deviation between the true air speed, angle of attack, and angle of sideslip measured by our system and a commercial Swiss air data system was 1 kt, 0.68°, and 0.54°, respectively, and those standard deviation between our system and a system with the same design but employing multiple single-axis telescopes with entrance pupil diameter of 30 mm was 0.34 kt, 0.36°, and 0.28°, respectively. The signal-to-noise ratio of our system was 4.5 times higher than that of the system with small single-axis telescopes. Our system is very promising for airborne applications because of its small volume, high signal-to-noise ratio, and high data rate.

Amphiphilic Superspreading Polymer Membranes Prepared by Capillary Force-Driven Self-Assembly.

To overcome the two main obstacles of large-scale application of superspreading material, self assembly is used to prepare superspreading polymer membrane (SPPM) in this work. An amphiphilic SPPM is prepared by capillary force-driven self assembly using PP melt-blown nonwovens and polyvinyl alcohol (PVA). The prepared SPPM has low preparation cost and stable performance since self assembly needs low energy consumption, and the production is thermodynamically stable. By using cryo-electron microscopy, transmission electron microscopy, X-ray photoelectron spectrum and scanning electron microscope with energy dispersive X-ray spectroscopy. It is proved that PVA is successfully assembled on the fiber surface of PP melt-blown nonwovens. The prepared SPPM has excellent spreading performance, the "spreading times" of both water and oil are less than 0.5 s. They showed much superior performance compared to traditional materials when applied in oil-water separation, seawater desalination, and ion separation. This work will definitely promote the development of self assembly, superspreading materials, and related sciences.

A Self-Assemble Supramolecular Film with Humidity Visualization Enabled by Clusteroluminescence.

Clusteroluminescence (CL) has recently gained significant attention due to its unique through-space interactions associated with a high dependence on the aggregation of subgroups. These distinct features could easily transform the stimuli into visual fluorescence and monitor the fluctuation of the environment but have not received sufficient attention before. In this work, supramolecular films are designed based on the neutralization reaction of anhydride groups and the self-assembly of dynamic covalent disulfide bonds in NaOH aqueous solution. The self-assembly of hydrophilic carboxylate chromophores and hydrophobic disulfide-containing five-membered rings could be observed by the variation of the aggregation state of carboxylate in CL. Furthermore, the dynamic cross-linking films obtained with water-sensitive carboxylate chromophores could alter the aggregation distance stimulated by surrounding water vapor, causing the emission wavelength to change from 534 to 508 nm by varying the relative humidity. This work not only provides an approach to monitor the self-assembly of clusteroluminogens but also offers new strategies for designing stimuli-responsive materials that utilize the intrinsic features of CL.

Branched Copolymers with Tunable Clusteroluminescence in High Quantum Yield.

A novel type of fluorescence without large conjugated structures called clusteroluminescence (CL) has attracted a great deal of attention in recent years. Despite its many advantages, the emerging CL still encounters difficulties of low quantum yield (QY) and preliminary mechanisms. In this work, the branched structure was introduced into poly(maleic anhydride-alt-vinyl acetate) by chain transfer monomer. The emission wavelength of the branched copolymers is red-shifted with the increase of branching degree, and the absolute QY of solids can reach up to 29.87%. Further characterizations reveal that the branched structure can improve the flexibility of polymer chains, thereby promoting the intrachain interactions of subgroups. Furthermore, in the case of branched anhydride copolymers, the equilibrium between intrachain interactions and nonradiative transitions holds a crucial significance in determining the QY. This endeavor not only offers new insights into the mechanism of CL but also presents a novel approach to surmount the low QY of anhydride copolymers, thus broadening the horizons of CLgens to unexplored domains.

Tunable Red Clusteroluminescence Polymers Prepared by a Simple Heating Process.

Clusteroluminescence (CL) has drawn much attention in recent years. However, the design of red emission clusteroluminogens (CLgens) with tunable CL is still in its infancy. Herein, we report a simple heating process to prepare red emission poly(maleic anhydride-alt-vinyl acetate) (PMV) derivatives with a tunable maximum emission wavelength between 620 and 675 nm. First, heating above the glass transition temperature (Tg) would promote the movement of polymer chains and facilitate the formation of clusters in both solid and solution states. Then, heating beyond the decomposition temperature at which vinyl acetate converts into C═C is favorable to the formation of new clusters and large through-space conjugation among subgroups in polymer chains. Their synergistic effects realize the adjustable emission wavelength and higher quantum yield of polymers. Additionally, low-cost and eco-friendly core-shell PMV particles are prepared as agricultural light conversion agents and exhibit great compatibility with polyethylene.

Improve Quantum Yield of Poly(Maleic Anhydride-Alt-Vinyl Acetate) via Good Solvents.

In this study, the optical properties of poly(maleic anhydride-alt-vinyl acetate) (PMV) synthesized by different polymerization methods are studied systematically. Compared to self-stabilized precipitation polymerization (pPMV), solution polymerization produces PMV solids (sPMV) with an extraordinarily high quantum yield (QY) of 20.65%. Additionally, redissolving pPMV in good solvents (rPMV) will also help to increase QY. The rising QY of sPMV and rPMV supports the idea that good solvents will reduce the rigidity of polymer chains and promote cluster formation, which is confirmed by lower glass transition temperature (Tg ) and small angle X-ray scatterer (SAXS). The study also finds that PMV exhibits application potentials in white light-emitting diodes (WLEDs) and light conversion film.

Pistachio-Inspired Bulk Graphene Oxide-Based Materials with Shapeability and Recyclability.

Nowadays, despite the fact that recent progress has been reported to mimic natural structural materials (especially nacre), designing bioinspired ultrastrong composites in a universal, viable, and scalable manner still remains a long-standing challenge. In particular, pistachio shells show high tissue strength attributed to the cellulose sheet laminated microstructures. Compared with nacre, pistachio shells own interlocking mortise-tenon joints in their structure, which offer higher energy dissipation and deformability. Here we present a strategy to produce nanocomposites with pistachio-mimetic structures through repeated kneading of graphene oxide (GO) in a dynamic covalent and supramolecular poly(sodium thioctic) (pST) system. The dynamic nature of the polymeric backbones endows the resultant GO-based composite with full recyclability and three-dimensional shapeability. The superior mechanical properties of the pistachio-mimetic composite can be attributed to the mortise-tenon joints design in the structure, which has not been achieved in the nacre-mimetic composite. The resulting composite also exhibits high thermal conductivity (15.6 W/(m·K)), yielding an alternative approach to design in engineered and thermal management materials.

Self-Perpetuating Carbon Foam Microwave Plasma Conversion of Hydrocarbon Wastes into Useful Fuels and Chemicals.

White wastes (unseparated plastics, face masks, textiles, etc.) pose a serious challenge to sustainable human development and the ecosystem and have recently been exacerbated due to the surge in plastic usage and medical wastes from COVID-19. Current recycling methods such as chemical recycling, mechanical recycling, and incineration require either pre-sorting and washing or releasing CO2. In this work, a carbon foam microwave plasma process is developed, utilizing plasma discharge to generate surface temperatures exceeding ∼3000 K in a N2 atmosphere, to convert unsorted white wastes into gases (H2, CO, C2H4, C3H6, CH4, etc.) and small amounts of inorganic minerals and solid carbon, which can be buried as artificial "coal". This process is self-perpetuating, as the new solid carbon asperities grafted onto the foam's surface actually increase the plasma discharge efficiency over time. This process has been characterized by in situ optical probes and infrared sensors and optimized to handle most of the forms of white waste without the need for pre-sorting or washing. Thermal measurement and modeling show that in a flowing reactor, the device can achieve locally extremely high temperatures, but the container wall will still be cold and can be made with cheap materials, and thus, a miniaturized waste incinerator is possible that also takes advantage of intermittent renewable electricity.

Chemical Recycling of Plastics by Microwave-Assisted High-Temperature Pyrolysis.

Use of plastics faces much criticism because of its shocking and increasing impact on the environment. But banning plastic will not help the environment. Only appropriate recycling of plastic waste can give satisfying solution. A lab-scale chemical recycling method, in which a mixture of plastic wastes and plant oil is continuously cracked into ethylene, propylene, and other useful chemicals by using microwave-assisted high-temperature pyrolysis, is developed. The method has delivered interesting leads that provide the basis for setting up a new process. Based on the encouraging results, a "drop-in" method for a renewable and circular polymer industry is also proposed. If it is commercially realized, plastic waste and plant oils will be the feedstock for the polymer industry and this industry will become renewable and circular.

Conductive Graphene-Melamine Sponge Prepared via Microwave Irradiation.

A conductive graphene-melamine sponge (MS) prepared via microwave irradiation is reported in this paper. Graphene oxide supported on the MS was prereduced first at 100 °C and then further reduced in a household microwave oven at over 1000 °C. It was surprising to find that graphene oxide on the MS was reduced perfectly while the three-dimensional structure of the MS was kept well after high-temperature reduction via microwave irradiation. Slight pyrolysis of MS was also found during 5 s microwave irradiation, resulting in nitrogen generation from the pyrolysis of the MS being doped into graphene, which could benefit the electric conductivity of the prepared graphene-MS. The electric conductivity of the prepared graphene-MS is about 0.12-1.0 S/m because of the high reduction degree of graphene oxide and nitrogen doping. On the other hand, different from the pure MS, the newly developed conductive graphene-MS possesses superhydrophobic and superoleophilic properties. Overall, the newly developed conductive graphene-MS contained 94.3 wt % MS and 5.7 wt % N-doped graphene and is a cost-effective material with good elasticity, high conductivity, superhydrophobicity, and superoleophilicity.

A New Family of Photoluminescent Polymers with Dual Chromophores.

A new family of photoluminescent polymers with dual chromophores is prepared in this study by using poly(maleic anhydride-alt-vinyl acetate), acetone, and metal hydroxide. These polymers, which contain both bulky carboxylic ester groups and metal carboxylate groups, are found to be dual-emission photoluminescent, with a blue luminescence excitation-dependent group and a red luminescence excitation-independent group. These photoluminescence polymers with a nonconjugated structure and dual chromophores also show characteristics of aggregation-induced emission (AIE). The luminous intensities of the AIE fibers prepared using the polymers are found to increase after stretching, in contrast to traditional photoluminescent fibers with the aggregation-caused quenching property. The study also finds that the stretched fibers can emit the three primary colors when irradiated by ultraviolet, blue, and green light.

Preparation and application of N-doped carbon nanotube arrays on graphene fibers.

A new kind of carbon hybrid material with a unique structure and outstanding mechanical and functional properties is reported in this article. Nitrogen-doped carbon nanotube (CNT) arrays with inside located Ni particles are in situ grown on the surface of phenolic carbon modified graphene fibers during their conversion from graphene oxide fibers. The carbon hybrid fibers exhibit not only high tensile strength and elongation at the break, but also excellent flexibility since the CNT arrays cover all the surface of the highly strong graphene fiber. This well-constructed carbon material would be suitable for catalysts, polymer composites, hydrogen storage, oxygen reduction reaction etc.

Water-Soluble Polymers with Strong Photoluminescence through an Eco-Friendly and Low-Cost Route.

Photoluminescence (PL) of nonconjugated polymers brings a favorable opportunity for low-cost and nontoxic luminescent materials, while most of them still exhibit relatively weak emission. Strong PL from poly[(maleic anhydride)-alt-(vinyl acetate)] (PMV) from low-cost monomer has been found in organic solvents, yet the necessity of noxious solvents would hinder its practical applications. Herein, through a novel, eco-friendly, and one-step route, PMV-derived PL polymers can be fabricated with the highest quantum yield of 87% among water-soluble nonconjugated PL polymers ever reported. These PMV-derived polymers emit strong blue emission in both solutions and solids, and can be transformed into red-emission agents easily. These PL polymers exhibit application potentials in light-conversion agricultural films. It is assumed that this work not only puts forward a convenient preparation routine for nonconjugated polymers with high PL, but also provides an industrial application possibility for them.

Ultrastrong Graphene-Based Fibers with Increased Elongation.

A new method to prepare graphene-based fibers with ultrahigh tensile strength, conductivity, and increased elongation is reported. It includes wet-spinning the mixture of GO aqueous dispersion with phenolic resin solution in a newly developed coagulation bath, followed by annealing. The introduced phenolic carbon increased densification of graphene fibers through reducing defects and increased interfacial interaction among graphene sheets by forming new C-C bonds, thus resulting in the increasing of stiffness, toughness, and conductivity simultaneously.

Polymer-Supported Raney Nickel Catalysts for Sustainable Reduction Reactions.

Green is the future of chemistry. Catalysts with high selectivity are the key to green chemistry. Polymer-supported Raney catalysts have been found to have outstanding performance in the clean preparation of some chemicals. For example, a polyamide 6-supported Raney nickel catalyst provided a 100.0% conversion of n-butyraldehyde without producing any detectable n-butyl ether, the main byproduct in industry, and eliminated the two main byproducts (isopropyl ether and methyl-iso-butylcarbinol) in the hydrogenation of acetone to isopropanol. Meanwhile, a model for how the polymer support brought about the elimination of byproducts is proposed and confirmed. In this account the preparation and applications of polymer-supported Raney catalysts along with the corresponding models will be reviewed.

Intrinsically Conductive Polymer Fibers from Thermoplastic trans-1,4-Polyisoprene.

Herein, we report a new strategy to prepare conductive polymer fibers to overcome the insurmountable weakness of current conductive polymer fibers. First, special thermoplastic polymers are processed into polymer fibers using a conventional melt-spinning process, and then the nonconductive polymer fibers are converted into intrinsically conductive polymer fibers. Using this new strategy, intrinsically conductive polymer fibers have been prepared by melt spinning low-cost thermoplastic trans-1,4-polyisoprene and doping with iodine, which can be as fine as 0.01 mm, and the resistivity can be as low as 10(-2) Ω m. Moreover, it has been found that drawing can improve the orientation of trans-1,4-polyisoprene crystals in the fibers and, thus, the conductivity of the conductive polymer fibers. Therefore, conductive fibers with excellent conductivities can be prepared by large drawing ratios before doping. Such conductive polymer fibers with low cost could be used in textile, clothing, packing, and other fields, which would benefit both industry and daily life. The newly developed method also allows one to produce conductive polymers of any shape besides fibers for antistatic or conductive applications.

Hierarchical Layered Heterogeneous Graphene-poly(N-isopropylacrylamide)-clay Hydrogels with Superior Modulus, Strength, and Toughness.

Biological composites are renowned for their elaborate heterogeneous architectures at multiple scales, which lead to a unique combination of modulus, strength, and toughness. Inspired by biological composites, mimicking the heterogeneous structural design principles of biological composites is a powerful strategy to construct high-performance structural composites. Here, we creatively transfer some heterogeneous principles of biological composites to the structural design of nanocomposite hydrogels. Unique heterogeneous conductive graphene-PNIPAM-clay hydrogels are prepared through a combination of inhomogeneous water removal processes, in situ free-radical polymerization, and chemical reduction of graphene oxide. The nanocomposite hydrogels exhibit hierarchical layered heterogeneous architectures with alternate stacking of dense laminated layers and loose porous layers. Under tensile load, the stiff dense laminated layers serve as sacrificial layers that fracture at a relatively low strain, while the stretchable loose porous layers serve as energy dissipation layers by large extension afterward. Such local inhomogeneous deformation of the two heterogeneous layers enables the nanocomposite hydrogels to integrate superior modulus, strength, and toughness (9.69 MPa, 0.97 MPa, and 5.60 MJ/m(3), respectively). The study might provide meaningful enlightenments for rational structural design of future high-performance nanocomposite hydrogels.

Bioinspired Hierarchical Alumina-Graphene Oxide-Poly(vinyl alcohol) Artificial Nacre with Optimized Strength and Toughness.

Due to hierarchical organization of micro- and nanostructures, natural nacre exhibits extraordinary strength and toughness, and thus provides a superior model for the design and fabrication of high-performance artificial composite materials. Although great progress has been made in constructing layered composites by alternately stacking hard inorganic platelets and soft polymers, the real issue is that the excellent strength of these composites was obtained at the sacrifice of toughness. In this work, inspired by the layered aragonite microplatelets/chitin nanofibers-protein structure of natural nacre, alumina microplatelets-graphene oxide nanosheets-poly(vinyl alcohol) (Al2O3/GO-PVA) artificial nacre is successfully constructed through layer-by-layer bottom-up assembly, in which Al2O3 and GO-PVA act as "bricks" and "mortar", respectively. The artificial nacre has hierarchical "brick-and-mortar" structure and exhibits excellent strength (143 ± 13 MPa) and toughness (9.2 ± 2.7 MJ/m(3)), which are superior to those of natural nacre (80-135 MPa, 1.8 MJ/m(3)). It was demonstrated that the multiscale hierarchical structure of ultrathin GO nanosheets and submicrometer-thick Al2O3 platelets can deal with the conflict between strength and toughness, thus leading to the excellent mechanical properties that cannot be obtained using only one size of platelet. We strongly believe that the work presented here provides a creative strategy for designing and developing new composites with excellent strength and toughness.

Epoxy based nanocomposites with fully exfoliated unmodified clay: mechanical and thermal properties.

The unmodified clay has been fully exfoliated in epoxy resin with the aid of a novel ultrafine full-vulcanized powdered rubber. Epoxy/rubber/clay nanocomposites with exfoliated morphology have been successfully prepared. The microstructures of the nanocomposites were characterized by means of X-ray diffraction and transmission electron microscopy. It was found that the unmodified clay was fully exfoliated and uniformly dispersed in the resulting nanocomposite. Characterizations of mechanical properties revealed that the impact strength of this special epoxy/rubber/clay nanocomposite increased up 107% over the neat epoxy resin. Thermal analyses showed that thermal stability of the nanocomposite was much better than that of epoxy nanocomposite based on organically modified clay.