Synthesis of succinic acid-based polyamide through direct solid-state polymerization method: Avoiding cyclization of succinic acid

Succinic acid is an important synthetic monomer but it is difficult to use it as a precursor for synthesizing high molecular weight polyamide, due to its tendency to perform intra-cyclization reaction at high temperature. In order to solve this problem, in this paper, the direct solid-state polymerization (DSSP) method with the initial reactant, nylon salt which was composed of 1, 5-diaminopentane, succinic acid, and terephthalic acid, was applied to synthesize the bio-based copolyamide PA 5T/54. In comparison with the conventional melting polymerization method, the DSSP method can prevent the cyclization reaction of succinic acid effectively due to the lower reacting temperature as well as the restriction effect of the nylon salt. As a result, the product fabricated by DSSP method has higher molecular weight and much lighter color from red to white. Therefore, the DSSP method is advantageous for the synthesis of the polymers or copolymers composed of the succinic acid as the monomer. Furthermore, the polymerization mechanism proposed in this work can serve as a guidance for the design of the molecular structure and control of the polymerization process.     

Direct View on the Origin of High Li+ Transfer Impedance in All-Solid-State Battery

Large interfacial resistance plays a dominant role in the performance of all-solid-state lithium-ion batteries. However, the mechanism of interfacial resistance has been under debate. Here, the Li⁺ transport at the interfacial region is investigated to reveal the origin of the high Li⁺ transfer impedance in a LiCoO₂(LCO)/LiPON/Pt all-solid-state battery. Both an unexpected nanocrystalline layer and a structurally disordered transition layer are discovered to be inherent to the LCO/LiPON interface. Under electrochemical conditions, the nanocrystalline layer with insufficient electrochemical stability leads to the introduction of voids during electrochemical cycles, which is the origin of the high Li⁺ transfer impedance at solid electrolyte-electrode interfaces. In addition, at relatively low temperatures, the oxygen vacancies migration in the transition layer results in the formation of Co₃O₄ nanocrystalline layer with nanovoids, which contributes to the high Li⁺ transfer impedance. This work sheds light on the mechanism for the high interfacial resistance and promotes overcoming the interfacial issues in all-solid-state batteries.     

Non-Halogenated-Solvent Processed and Additive-Free Tandem Organic Solar Cell with Efficiency Reaching 16.67%

Organic solar cells (OSCs) have recently reached a remarkably high efficiency and become a promising technology for commercial application. However, OSCs with top efficiency are mostly processed by halogenated solvents and with additives that are not environmentally friendly, which hinders large-scale manufacture. In this study, high-performance tandem OSCs, based on polymer donors and two small-molecule acceptors with different bandgaps, are fabricated by solution processing with non-halogenated solvents without additive. Importantly, the two active layers developed from non-halogenated solvents show better phase segregation and charge transport properties, leading to superior performance than halogenated ones. As a result, a tandem OSC with high efficiency of up to 16.67% is obtained, showing unique advantages in future massive production.     

Deacetylated Cellulose Acetate/Polyurethane Composite Nanofiber Membranes with Highly Efficient Oil/Water Separation and Excellent Mechanical Properties

Nowadays, oil pollution has become more serious, which causes great threats both to the ecological environment and human life. In this study, a novel type of multifunctional deacetylated cellulose acetate/polyurethane (d-M_CA:M_TPU) composite nanofiber membranes for oil/water separation are successfully fabricated by electrospinning, which show super-amphiphilicity in air, super-hydrophilicity in oil, and oleophobicity in water. All the d-M_CA:M_TPU composite nanofiber membranes with different mass ratios can be used as water-removing, oil-removing, and emulsion separation substance only by gravity driving force. The highest separation flux for water and oil reaches up to 37 000 and 74 000 L m⁻² h⁻¹, respectively, and all the separation efficiencies are more than 99%. They have outstanding comprehensive mechanics performance, which can be controlled by simply adjusting the mass ratios. They show excellent antifouling and self-cleaning ability, endowing powerful cyclic stability and reusability. Those results show that d-M_CA:M_TPU composite nanofiber membranes have great application prospects in oil/water separation.     

Self-healing,elastic and deformable novel composite phase change polymer based on thermoplastic elastomer SEBS for wearable devices

Journal of Materials Science - Form-stable composite phase change materials (C-PCMs) prepared by microencapsulation method and porous matrix adsorption method need for compression molding after...     

InSAR技术在矿区地表变形监测中的应用

以禹州市梁北矿为研究区，利用2018年11月—2020年6月间35景5 m×20 m分辨率Sentinel-1A数据，采用InSAR技术，利用SBAS（短基线集InSAR）雷达干涉测量方法对梁北矿进行地面沉降信息提取解译，并通过实地调查成果认为，采用InSAR技术适合在矿区开展地表变形监测。     

Porous agarose/Gd-hydroxyapatite composite bone fillers with promoted osteogenesis and antibacterial activity

Artificial bone fillers are essentially required for repairing bone defects, and developing the fillers with synergistic biocompatibility and anti-bacterial activity persists as one of the critical challenges. In this work, a new agarose/gadolinium-doped hydroxyapatite filler with three-dimensional porous structures was fabricated. For the composite filler, agarose provides three-dimensional skeleton and endows porosity, workability, and high specific surface area, hydroxyapatite (HA) offers the biocompatibility, and the rare earth element gadolinium (Gd) acts as the antibacterial agent. X-ray photoelectron spectroscopy detection showed the doping of Gd in HA lattice with the formation of Gd-HA interstitial solid solution. Attenuated total reflection Fourier transform infrared spectroscopy imaging suggested chemical interactions between agarose and Gd-HA, and the physical structure of agarose was tuned by the Gd-doped HA. Cytotoxicity testing and alizarin red staining experiments using mouse pro-osteoblasts (MC3T3-E1) revealed remarkable bioactivity and osteogenic properties of the composite fillers, and proliferation and growth rates of the cells increased in proportion to Gd content in the composites. Antibacterial testing using the gram-positive bacteria S. aureus and the gram-negative bacteria E. coli indicated promising antibacterial properties of the fillers. Meanwhile, the antibacterial properties of composite filles were enhanced with the increase of Gd content. The antibacterial fillers with porous structure and excellent physicomechanical properties show inspiring potential for bone defect repair.     

Tuning lattice strain in biphenylene for enhanced electrocatalytic oxygen reduction reaction in proton exchange membrane fuel cells

As proton-exchange membrane fuel cell technology has grown and developed, there has been increasing demand for the design of novel catalyst architectures to achieve high power density and realize wide commercialization. Herein, based on the two-dimensional biphenylene, we compare the oxygen reduction reaction (ORR) activity on the active sites with different biaxial lattice strains using first-principles calculations. The ORR free energy diagrams of biphenylene monolayers with varying lattice strains suggest that the biaxial tensile strains are unfavorable for catalytic activity. In contrast, the biaxial compressive strains could improve the catalytic performance. The biphenylene systems with the strain of ?2% ～ ?6% (S_{-0.02～-0.06}) display overpotentials of 0.37–0.49 V. This performance is comparable to or better than the Pt (111) surface. The Bader charge transfer of adsorbed O species on various biaxial strain biphenylene catalysts could be a describer to examine the catalytic activity. The catalysts possessed the moderate transferred charge of O adsorbed species often promotes catalytic process and give the high catalysis efficiency. Overall, this work suggests that the lattice strain strategy can significantly enhance the catalytic activity of biphenylene materials and further provide guidance to design biphenylene-based catalysts in various chemical reactions.