A highly compressible hydrogel electrolyte for flexible Zn-MnO2 battery.

Compressibility of zinc-manganese oxide (Zn-MnO2) batteries is an essential element of modern flexible electronics. Hydrogel electrolytes with superior elasticity and compressibility are highly demand to guarantee a stable energy output of the flexible Zn-MnO2 battery. Herein, a highly compressible hydrogel electrolyte was developed by introducing soybean protein isolate nanoparticles (SPI) into covalently cross-linked polyacrylamide (PAAM) polymer networks. The SPI/PAAM hydrogel electrolyte for Zn-MnO2 battery possessed outstanding reversible compressibility due to the aggregation of SPI nanoparticles on the PAAM chains through the weak electrostatic interaction, which could dissipate energy effectively. Consequently, the Zn-MnO2 battery based on the compressible hydrogel electrolyte displayed a decent specific capacity (299.3 mA h g-1) and desirable capacity retention rate (78.2%) after 500 charge/discharge cycles. Notably, the device could maintain stable power output under 96% compress strain and light the bulb even under severe mechanical stimulation like being-bent and hammered. It's believed that the compressible Zn-MnO2 batteries hold enormous potential as the energy storage devices in the field of flexible wearable electronics.

ZnO Nanoneedle-Modified PEEK Fiber Felt for Improving Anti-fouling Performance of Oil/Water Separation.

Membrane separation has been considered to be the most effective decontamination method for oily waste water. The most significant point of membrane separation is the resistance against membrane fouling. Fabricating hierarchical architectures on the membrane surface is an available approach to improving its anti-fouling property. In this study, ZnO nanoneedles were successfully anchored onto surface-sulfonated poly(ether-ether-ketone) (PEEK) felt via UV/ozone cleaning and hydrothermal synthesis. The modified felt (PEEK-f-Z) showed much better anti-fouling properties and far higher rejection height (33 cm) than the unmodified felt (17 cm) with a separation efficiency up to 99.99%. The enhanced separation properties could be attributed to the stronger water locking capability of the hierarchical architectures on the surface. Furthermore, benefiting from the great chemical stability of PEEK substrates and ZnO nanoneedles, the as-prepared membrane exhibited admirable solvent resistance, mechanical strength, and thermal stability. As a result, PEEK-f-Z could even separate immiscible organic liquids with different polarities and collect hot water from the oil/water mixture, promising to be used under severe conditions.

Combined strategy of blending and surface modification as an effective route to prepare antifouling ultrafiltration membranes.

Ultrafiltration (UF) membranes blended with hydrophilic nanomaterials usually exhibit preferable overall performance including the membrane permeability and antifouling capability. However, the improvement in antifouling performance may be not outstanding due to the small amount of nanomaterial distributed near the membrane surface and the limited improvement in membrane hydrophilicity. Notably, excess addition of nanomaterials may lead to the decline in membrane permeability. In order to solve the above problem, we integrated the strategy of blending and surface modification to construct novel hybrid UF membranes. Novel nanohybrid was prepared via tannic acid (TA) coating on hydroxyapatite nanotubes (HANTs) and the subsequent grafting of zwitterionic polyethylenimine (ZPEI). The prepared nanohybrid (HANTs@TA-ZPEI) was incorporated with the polysulfone containing tertiary amine groups to fabricate hybrid membranes via the solution blending and the subsequent immersion-precipitation phase inversion process. Then the matrix was modified with zwitterions via the reaction of tertiary amine group with 1, 3-propane sultone. UF tests were conducted using the bovine serum albumin (BSA) and humic acid (HA) as the representative foulants. Results showed that both the permeability and the antifouling performance of the membranes achieved favorable promotion. Thereinto, the water flux of M-B0.4-Z membrane (pre blended with 0.4 wt% HANTs@TA-ZPEI in the casting solution and post-surface modified) exhibited 2.6 times that of the pristine membrane and the flux recovery ratio (FRR) for BSA and HA attained 93.4% and 96.1%, respectively. By the combination of blending and surface modification, both the membrane permeability and fouling resistant properties could attain remarkable promotion, which exerted the advantages of two methods and made up the deficiency of single blending method.

Strong Interface Construction of Carbon Fiber-reinforced PEEK Composites: An Efficient Method for Modifying Carbon Fiber with Crystalline PEEK.

In order to improve the poor solvent resistance and poor temperature resistance caused by traditional sizing agents, crystalline poly(ether ether ketone) (PEEK) is introduced to the interfacial phases of carbon fiber (CF) reinforced PEEK composites by a soluble precursor named PEEK-1,3-dioxolane. By changing the soluble precursor molecular weight and concentration in the sizing solution, the content of PEEK coated on the CF fiber surface can be controlled and the different interfacial properties of the PEEK composites can be obtained. The results shows that, with this method, crystalline PEEK can be completely coated on the CF surface, and the interfacial shear strength of the PEEK composites increases from 43.42 to 83.13 MPa. Due to none of any soluble compounds in the PEEK composites, the interfacial layer is well preserved under organic solvents and hygrothermal conditions, and the interfacial shear strength (IFSS) of the PEEK composites maintained above 85.4% and 90.44%, respectively. Scanning electron microscope clarifies that the mechanism of interface enhancement comes from a better wetting of crystalline PEEK on the fiber surface. Additionally, the sizing system of this investagation has the potential commercial value because of no toxic reagent (such as 2,4,5-trichloro-1-hydroxy-benzene or concentrated sulfuric acid) is required during sizing.

Development of highly permeable and antifouling ultrafiltration membranes based on the synergistic effect of carboxylated polysulfone and bio-inspired co-deposition modified hydroxyapatite nanotubes.

Hybridization has become a powerful toolbox for developing ultrafiltration membranes with superior properties. However, it remains challenging to give full play to the utility of nanofillers because of poor bonding strength between polymers and inorganic nanomaterials. Herein, hydroxyapatite nanotubes (HANTs) were modified via bio-inspired polydopamine (PDA) and polyethylenimine (PEI) co-deposition. Meanwhile, polysulfone with carboxylation degree of 30% (PSF-COOH-30%) was synthesized by nucleophilic substitution reaction and employed as the membrane matrix. The results showed that when 0.3 wt% HANTs@PDA/PEI was incorporated, the pure water flux of the hybrid membrane achieved about 3.2 times that of the unfilled membrane and the rejection rate of bovine serum albumin (BSA) and humic acid (HA) remained 94.5% and 97.8%, respectively. Meanwhile, the flux recovery ratio for BSA and HA solutions (1 g/L) reached 90.8% and 93.7%, respectively. Specifically, the superiority of UF performance benefited from the synergistic effect of both the carboxylated polymer and the nanofiller. On one hand, the incorporation of HANTs@PDA/PEI promoted the formation of more porous membrane structure and improved the hydrophilicity of the membrane. On the other hand, due to the existence of COOH, the electrostatic repulsion between the membranes and contaminants enhanced the fouling resistance for BSA and HA. Conspicuously, the ease and versatility of co-deposition provide new ideas in the construction of nanohybrid and the favorable improvement renders that appropriate combination of polymer and additive is an effective way for developing future ultrafiltration membranes.

Preparation and Performance of Poly(D,L-lactic acid)­Polyethylene Glycol­Poly(D,L-lactic acid) Electrospun Fibrous Membranes for Drug Release.

In this study, poly(D,L-lactic acid)­polyethylene glycol­poly(D,L-lactic acid), hereafter referred to as PDLLA­PEG­PDLLA, triblock copolymer membranes were prepared by electrospinning. Scanning electron microscopy images revealed the morphology of the microfibers, which had a diameter ranging from 300 to 900 nm. Fourier transform infrared spectroscopy was employed for structural analysis of the PDLLA­PEG­PDLLA/florfenicol (FF) membranes, which exhibited three absorption peaks at 3455, 1684, and 1533 cm−1, respectively, indicating that the triblock copolymer and FF are very well blended in the composite membranes. Differential scanning calorimetry revealed that weak interaction possibly decreased the activity of the segment and elevated the T g from 43 °C to 46 °C. From the in vitro dissolution tests, PDLLA as a biodegradable and biocompatible polymer can improve the solubility of FF. The rate of drug release increased with increasing PEG proportion. Furthermore, tensile and nanoindentation tests demonstrated that nanofibers exhibit mechanical properties such as tensile stress (700­2800 KPa), strain (40­120%), and good toughness (0.28­0.98 GPa). In conclusion, PDLLA­PEG­PDLLA nanofibers as a carrier improve the solubility of FF and control drug release.