Schiff-base polymer derived FeCo-N-doped porous carbon flowers as bifunctional oxygen electrocatalyst for long-life rechargeable zinc-air batteries

Rational design and exploration of low-cost and robust bifunctional oxygen electrocatalysts are vitally important for developing high-performance zinc-air batteries(ZABs).Herein,we reported a facile yet cost-efficient approach to construct a bifunctional oxygen reduction reaction(ORR)/oxygen evolution reaction(OER)electrocatalyst composed of N-doped porous carbon nanosheet flowers decorated with Fe Co nanoparticles(Fe Co/N-CF).Rational design of this catalyst is achieved by designing Schiff-base polymer with unique molecular structure via hydrogen bonding of cyanuramide and terephthalaldehyde polycondensate in the presence of metal cations.It exhibits excellent activity and stability for electrocatalysis of ORR/OER,enabling ZAB with a high peak power density of 172 m W cm^(-2)and a large specific capacity of 811 m A h g^(-1)Znat large current.The rechargeable ZAB demonstrates excellent durability for 1000 h with slight voltage decay,far outperforming a couple of precious Pt/Ir-based catalysts.Density functional theory(DFT)calculations reveal that high activity of bimetallic Fe Co stems from enhanced O_(2)and OH-adsorption and accelerated O_(2)dissociation by OAO bond activation.

高度取向磷酸锆/环氧树脂纳米复合涂层的防腐蚀性能

针对金属防腐蚀的需求,采用简单的喷涂法在金属基底上制备了高度取向磷酸锆/环氧树脂纳米复合涂层。利用透射电镜和X射线衍射分析探究了复合涂层中磷酸锆纳米粒子的分散形貌,采用电化学交流阻抗谱和动电位极化曲线等测试评价了复合涂层的防腐蚀性能和其作用机理。结果表明,高度取向的磷酸锆纳米粒子可有效地增加水、氧气、电解液的扩散路径,改善涂层的防腐蚀性能。此外,该绝缘涂层也可进一步阻止腐蚀介质的迁移,增加涂层电阻,显著提高环氧树脂涂层对金属基底的长期防护性能。

Noncovalent cross-linked engineering hydrogel with low hysteresis and high sensitivity for flexible self-powered electronics

In this study,the hydrogel network was reinforced by covalent-like hydrogen bonding,and the strong binding ability of boron-nitrogen coordination served as the main driving force.Among them,acrylamide(AM)and 3-acrylamidophenylboronic acid(AAPBA)were the main body,and the numerous hydroxyl groups in the trehalose(Treh)molecule and other polymer groups formed strong hydrogen bonding interactions to improve the mechanical properties of the PAM/PAAPBA/Treh(PAAT)hydrogel and ensured the simplicity of the synthesis process.The hydrogel possessed high strain at break(1239%),stress(64.7 kPa),low hysteresis(100%to 500%strain,corresponding to dissipation energy from 1.37 to 7.80 kJ/m^(3)),and outstanding cycling stability(retained more than 90%of maximum stress after 200 ten-sile cycles).By integrating carbon nanotubes(CNTs)into PAAT hydrogel(PAATC),the PAATC hydrogel with excellent strain response performance was successfully constructed.The PAATC conductive hydro-gel exhibited high sensitivity(gauge factor(GF)=10.58 and sensitivity(S)=0.304 kPa^(-1)),wide strain response range(0.5%-1000%),fast response time(450 ms),and short recovery time(350 ms),excellent fatigue resistance,and strain response stability.Furthermore,the PAATC-based triboelectric nanogener-ator(TENG)displayed outstanding energy harvesting performance,which shows its potential for appli-cation in self-powered electronic devices.

The Capture and Catalytic Conversion of CO_(2) by Dendritic Mesoporous Silica-Based Nanoparticles

Dendritic mesoporous silica nanoparticles own three-dimensional center-radial channels and hierarchical pores,which endows themselves with super-high specific surface area,extremely large pore volumes,especially accessible internal spaces,and so forth.Dissimilar guest species(such as organic groups or metal nanoparticles)could be readily decorated onto the interfaces of the channels and pores,realizing the functionalization of dendritic mesoporous silica nanoparticles for targeted applications.As adsorbents and catalysts,dendritic mesoporous silica nanoparticles-based materials have experienced nonignorable development in CO_(2)capture and catalytic conversion.This comprehensive review provides a critical survey on this pregnant subject,summarizing the designed construction of novel dendritic mesoporous silica nanoparticles-based materials,the involved chemical reactions(such as CO_(2)methanation,dry reforming of CH_(4)),the value-added chemicals from CO_(2)(such as cyclic carbonates,2-oxazolidinones,quinazoline-2,4(1H,3H)-diones),and so on.The adsorptive and catalytic performances have been compared with traditional silica mesoporous materials(such as SBA-15 or MCM-41),and the corresponding reaction mechanisms have been thoroughly revealed.It is sincerely expected that the in-depth discussion could give materials scientists certain inspiration to design brand-new dendritic mesoporous silica nanoparticles-based materials with superior capabilities towards CO_(2)capture,utilization,and storage.

Fabrication and Characterization of Bamboo—Epoxy Reinforced Composite for Thermal Insulation

As global warming intensifies, researchers worldwide strive to develop effective ways to reduce heat transfer. Among the natural fiber composites studied extensively in recent decades, bamboo has emerged as a prime candidate for reinforcement. This woody plant offers inherent strengths, biodegradability, and abundant availability. Due to its high cellulose content, its low thermal conductivity establishes bamboo as a thermally resistant material. Its low thermal conductivity, enhanced by a NaOH solution treatment, makes it an excellent thermally resistant material. Researchers incorporated Hollow Glass Microspheres (HGM) and Kaolin fillers into the epoxy matrix to improve the insulating properties of bamboo composites. These fillers substantially enhance thermal resistance, limiting heat transfer. Various compositions, like (30% HGM + 25% Bamboo + 65% Epoxy) and (30% Kaolin + 25% Bamboo + 45% Epoxy), were compared to identify the most efficient thermal insulator. Using Vacuum Assisted Resin Transfer Molding (VARTM) ensures uniform distribution of fillers and resin, creating a structurally sound thermal barrier. These reinforced composites, evaluated using the TOPSIS method, demonstrated their potential as high-performance materials combating heat transfer, offering a promising solution in the battle against climate change.

MXene@c-MWCNT Adhesive Silica Nanofiber Membranes Enhancing Electromagnetic Interference Shielding and Thermal Insulation Performance in Extreme Environments

A lightweight flexible thermally stable composite is fabricated by com-bining silica nanofiber membranes(SNM)with MXene@c-MWCNT hybrid film.The flexible SNM with outstanding thermal insulation are prepared from tetraethyl orthosilicate hydrolysis and condensation by electrospinning and high-temperature calcination;the MXene@c-MWCNT_(x:y)films are prepared by vacuum filtration tech-nology.In particular,the SNM and MXene@c-MWCNT_(6:4)as one unit layer(SMC_(1))are bonded together with 5 wt%polyvinyl alcohol(PVA)solution,which exhibits low thermal conductivity(0.066 W m^(-1)K^(-1))and good electromagnetic interference(EMI)shielding performance(average EMI SE_(T),37.8 dB).With the increase in func-tional unit layer,the overall thermal insulation performance of the whole composite film(SMC_(x))remains stable,and EMI shielding performance is greatly improved,especially for SMC_(3)with three unit layers,the average EMI SET is as high as 55.4 dB.In addition,the organic combination of rigid SNM and tough MXene@c-MWCNT_(6:4)makes SMC_(x)exhibit good mechanical tensile strength.Importantly,SMC_(x)exhibit stable EMI shielding and excellent thermal insulation even in extreme heat and cold environment.Therefore,this work provides a novel design idea and important reference value for EMI shielding and thermal insulation components used in extreme environmental protection equipment in the future.

TUNED MECHANICAL PROPERTIES ACHIEVED BY VARYING POLYMER STRUCTURE-KNOWLEDGE THAT GENERATES NEW MATERIALS FOR TISSUE ENGINEERING

By changing both the monomer composition and the polymer structure, we have varied the mechanical properties of resorbable polymers. The polymers were synthesized by ring-opening polymerization using L-lactide （LLA）, ε-caprolactone （εCL）, trimethylene carbonate （TMC） and 1,5-dioxepan-2-one （DXO） as monomers. Well-defined triblock copolymers, microblock copolymers and networks have been evaluated, and comparisons between them show that it is possible to tune the mechanical properties. Triblock copolymers with an amorphous middle block of poly（1,5-dioxepan-2- one） （PDXO） and semi-crystalline end-blocks of poly（ε-caprolactone） （PCL） were stronger and had a higher strain at break than triblock copolymers with poly（L-lactide） （PLLA） as end-blocks. Polymers with both DXO and TMC in the amorphous middle-block and PLLA as end-blocks showed a lower stress at break, but the material gained elasticity, a property which is very valuable in tissue engineering. Mechanical properties of networks, synthesized by a novel method, containing PDXO and PCL are also presented. Although it is difficult to compare them with the uncross-linked polymers, this is an additional way to modify and widen the properties.

LAMINATION OF POLYMER FILMS BY BULK SURFACE PHOTOGRAFTING PROCESS AND PROPERTIES

A new process for lamination of polymer films by 'bulk surface photografting' has been developed. The chemical component of the invention is that the curing of reactive solution between two substrates is initiated by the surface free radicals produced by aromatic ketones and surface-hydrogen of substrates. Using the new approach, two or more polymer films are bonded together by a grafted polymer network which is grafted to adjacent substrate surfaces. The technique has been applied to film substrates of different polymers such as polyolefins, polyesters, and polyamides which have abstractable hydrogens at the surface. The photolaminated film composites containing carrier films and an intermediate functional film of low permeability give strong laminates with high barrier properties, e.g, for oxygen and air.

Natural fiber reinforced polymer composites: history, types, advantages and applications

Nowadays, the use of natural fiber reinforced polymer-based composites is gradually increasing day by day for their many advantages for civil engineering construction applications. Due to their many advantages for polymer-based composite materials are widely used in civil construction, automobiles, aerospace, and many others. Natural fibers such as jute, kenaf, pineapple, sugarcane, hemp, oil palm, flax, and leaf, etc. are cheap, environmentally friendly, renewable, completely and partially biodegradable which can be utilized to obtain new high-performance polymer materials. These composites are having satisfactory mechanical properties (i.e. tensile properties, flexural stress-strain behavior, fracture toughness, and fracture strength) which make them more attractive than other composites. Due to easy availability and renewability, natural fibers can be used as an alternative of synthetic fibers as a reinforcing agent. The aim of this paper is to review different natural fibers reinforced based polymer composites with mechanical characterization, applications, also shows the opportunities, challenges and future demand of natural composite material towards civil applications.

A crosslinked polymer as dopant-free hole-transport material for efficient n-i-p type perovskite solar cells

A new crosslinked polymer,called P65,with appropriate photo-electrochemical,opto-electronic,and thermal properties,has been designed and synthesized as an efficient,dopant-free,hole-transport material(HTM)for n-i-p type planar perovskite solar cells(PSCs).P65 is obtained from a low-cost and easily synthesized spiro[fluorene-9,90-xanthene]-30,60-diol(SFX-OH)-based monomer X65 through a freeradical polymerization reaction.The combination of a three-dimensional(3 D)SFX core unit,holetransport methoxydiphenylamine group,and crosslinked polyvinyl network provides P65 with good solubility and excellent film-forming properties.By employing P65 as a dopant-free hole-transport layer in conventional n-i-p type PSCs,a power conversion efficiency(PCE)of up to 17.7%is achieved.To the best of our knowledge,this is the first time a 3 D,crosslinked,polymeric dopant-free HTM has been reported for use in conventional n-i-p type PSCs.This study provides a new strategy for the future development of a 3 D crosslinked polymeric dopant-free HTM with a simple synthetic route and low-cost for commercial,large-scale applications in future PSCs.

A brief review on natural fiber used as a replacement of synthetic fiber in polymer composites

The use of composites in different sectors has become inevitable due to the enhancement in properties, reduction in the manufacturing cost and suitability to several applications. Among different classifications, polymeric composites are mainly focused on their use as structural components and the selection and composition of reinforcement play a vital role in determining the characteristics of the composite. Although composites are developed with man-made reinforcement in the beginning stage, in the present situation, natural reinforcements have proved excellent results in terms of properties. Hence, nowadays researches are mainly focused on the use of different natural fibers in different forms as reinforcements in polymeric composite. This work presents a brief overview on the properties of natural fiber and natural fiber reinforced composites which is an emerging area in polymer science. Interests in natural fiber is reasonable due to the advantages of these materials compared to others, such as synthetic fiber composites, including low environmental impact and low cost and support their potential to be used. Moreover, the disadvantage of the synthetic and fiber-glass as reinforcement, the use of natural fiber reinforced composite gained the attention of the young scientists, researchers, and engineers and are being exploited as a replacement for the conventional fiber such as glass, aramid, carbon etc. Natural fibers have been proven alternative to synthetic fiber in transportation such as automobiles, railway coaches and aerospace, military, building, packaging, consumer products and construction industries for ceiling paneling, partition boards etc. However, in development of these composites, some drawbacks have also emerged. In this paper, it has been tried to overview all of this together.

Biopolymer passivation for high-performance perovskite solar cells by blade coating

Thin films of perovskite deposited from solution inevitably introduce large number of defects,which serve as recombination centers and are detrimental for solar cell performance.Although many small molecules and polymers have been delicately designed to migrate defects of perovskite films,exploiting credible passivation agents based on natural materials would offer an alternative approach.Here,an ecofriendly and cost-effective biomaterial,ploy-L-lysine(PLL),is identified to effectively passivate the defects of perovskite films prepared by blade-coating.It is found that incorporation of a small amount(2.5 mg mL^(-1))of PLL significantly boosts the performance of printed devices,yielding a high efficiency of 19.45% with an increase in open-circuit voltage by up to 100 mV.Density functional theory calculations combined with X-ray photoelectron spectroscopy reveal that the functional groups(-NH2,-COOH)of PLL effectively migrate the Pb-I antisite defects via Pb-N coordination and suppress the formation of metallic Pb in the blade-coated perovskite film.This work suggests a viable avenue to exploit passivation agents from natural materials for preparation of high-quality perovskite layers for optoelectronic applications.

Poly(phenylene oxide) and Renewable Polyamide 11 Blends Compatibilized by Ethylene-n-Octene Copolymer

Poly(phenylene oxide)/renewable polyamide 11 (PPO/PA11 20/80) blends toughened with glycidylmethacrylate grafted ethylene-n-octene copolymer (GEOC) were prepared in a co-rotating twin-screwextruder. The reaction between GEOC and PPO/PA11 blend was analyzed by gel content tests. Themorphology of PPO/PA11/GEOC blends was observed by scanning electron microscope. The SEMresults showed that PPO formed the continuous phase, though it is a minority component of blends. Withincreasing GEOC content from 5 to 15 wt% the morphology of the blends transformed from droplet-matrix toco-continuous structure, in which both PA11 and PPO phases are continuous. The blend with co-continuousmorphology had better mechanical properties than those with droplet-matrix morphology. The impactstrength of the PPO/PA11/GEOC blends was much higher compared to the one without GEOC as well asPA11 due to the compatibilizing effect, which was also proved by DSC analysis, rheological behavior (MFR,DMTA) and tensile properties.

MAGNETIC FIELD EFFECT ON PHOTOPOLYMERIZATION OF STYRENE MICROEMULSION

External magnetic field increases the photo-induced polymerization rate of styrene microemulsion.The type of photoinitiator plays an important role. The photoinitiators, used are dimethoxyphenyl acetophenone(DMPA), 1-hydroxycyclohexyl phenylketone (Irgacure 184) and dimethylhydroxyacetophenone (Darocur 1173). No magnetic effect was observed by using dibenzylketone (DBK) as photoinitiator. The molecular weight of the polymer is slightly affected by magnetic field. The influence of temperature has also been investigated.

Polymer Analyses for an Adapted Process Design of the Pipe-Extrusion of Polyetherimide

Over the last years, the use of high performance thermoplastic materials increased significantly especially in aviation applications. Thus, the processing of these high temperature polymers became more and more interesting. Especially, the groups of polymers like polyphenylene sulfide (PPS), polyether ether ketone (PEEK) or polyetherimide (PEI) are in the focus of recent developments and investigations. These materials show excellent thermal, mechanical and chemical properties while processing remains still challenging. Especially the influence of processing temperatures, temperature depending viscosities, the specific heat capacities and the thermal expansion show a high impact to the quality of the produced parts, e.g. degradation and dimensionally stability. Thus, this paper shows experimental characterizations in regard to the processing of PEI by pipe extrusion processes. In this context, a suitable methodology for the determination of appropriate process parameters is shown, which includes the comprehensive determination of temperature dependent thermal, thermomechanical and degradation properties of specific PEI extrusion materials.

Advancing the pressure sensing performance of conductive CNT/PDMS composite film by constructing a hierarchical-structured surface

Flexible pressure sensors have attracted wide attention due to their applications to electronic skin,health monitoring,and human-machine interaction.However,the tradeoff between their high sensitivity and wide response range remains a challenge.Inspired by human skin,we select commercial silicon carbide sandpaper as a template to fabricate carbon nanotube(CNT)/polydimethylsiloxane(PDMS)composite film with a hierarchical structured surface(h-CNT/PDMS)through solution blending and blade coating and then assemble the h-CNT/PDMS composite film with interdigitated electrodes and polyurethane(PU)scotch tape to obtain an h-CNT/PDMS-based flexible pressure sensor.Based on in-situ optical images and finite element analysis,the significant compressive contact effect between the hierarchical structured surface of h-CNT/PDMS and the interdigitated electrode leads to enhanced pressure sensitivity and a wider response range(0.1661 kPa^(-1),0.4574 kPa^(-1)and 0.0989 kPa^(-1)in the pressure range of 0–18 kPa,18–133 kPa and 133–300 kPa)compared with planar CNT/PDMS composite film(0.0066 kPa^(-1)in the pressure range of 0–240 kPa).The prepared pressure sensor displays rapid response/recovery time,excellent stability,durability,and stable response to different loading modes(bending and torsion).In addition,our pressure sensor can be utilized to accurately monitor and discriminate various stimuli ranging from human motions to pressure magnitude and spatial distribution.This study supplies important guidance for the fabrication of flexible pressure sensors with superior sensing performance in next-generation wearable electronic devices.

基于一步法制备超高PEO负载的亲CO_(2)气体分离膜用于高效碳捕集

针对日益增加的大气CO_(2)含量,膜技术被认为是一种有前景的碳捕集策略,其中亲CO_(2)分离膜已经展示出显著的应用潜力,特别是在CO_(2)/轻质气体分离方面。以聚环氧乙烷(PEO)为代表的CO_(2)亲和材料,因其与CO_(2)的特殊偶极-四极矩相互作用而吸引了广泛的研究关注。在此,我们报道了一种简便的一步合成方案,通过原位聚合高度柔性的小分子PEO来克服其高结晶度和低机械强度的局限性。得益于短链PEO与聚合物基体之间的复杂链缠绕,使线性PEO的负载高达90%(质量分数)。因此,分离性能轻松超过了著名的分离上限。此外,高结构稳定性使得分离膜在高进料压力(高达20 bar)下表现出更好的CO_(2)渗透系数和气体选择性。本研究同时改善了全聚合物膜的机械性能和气体分离性能,在工业碳捕集和气体净化领域展现出显著潜力。

硅粉水泥石中微孔孔径分布及其对强度的影响

采用X射线小角度散射(SAXS)技术,对硅粉水泥石中微孔孔径分布(孔半径小于50nm)进行了实验研究,并讨论了孔径分布对强度的影响.研究表明:所测硅粉水泥石的孔径均呈多峰分布,其平均孔半径约在4.5～9.0nm,最可几孔半径约在4.0～6.5nm;硅粉含量、水灰比对孔径分布有显著影响,随着硅粉含量的增加以及水灰比的减小,孔径分布向小孔方向移动;孔径分布与抗压强度有较好的相关性,而孔径分布(孔半径小于50nm)与抗折强度之间不存在明显的相关性.