Lightweight diamond/Cu interface tuning for outstanding heat conduction

With rapid developments in the field of very large-scale integrated circuits,heat dissipation has emerged as a significant factor that restricts the high-density integration of chips.Due to their high thermal conductivity and low thermal expansion coefficient,diamond/Cu composites have attracted considerable attention as a promising thermal management material.In this study,a surface tungsten carbide gradient layer coating of diamond particles has been realized using comprehensive magnetron sputtering technology and a heat treatment process.Diamond/Cu composites were prepared using high-temperature and high-pressure technology.The results show that,by adjusting the heat treatment process,tungsten carbide and di-tungsten carbide are generated by an in situ reaction at the tungsten–diamond interface,and W–WC–W_(2)C gradient layer-coated diamond particles were obtained.The diamond/Cu composites were sintered by high-temperature and high-pressure technology,and the density of surface-modified diamond/Cu composites was less than 4 g cm^(-3).The W–WC–W_(2)C@diamond/Cu composites have a thermal diffusivity as high as 331 mm^(2)s^(-1),and their thermal expansion coefficient is as low as 1.76×10^(-6)K^(-1).The interface coherent structure of the gradient layer-coated diamond/copper composite can effectively improve the interface heat transport efficiency.

Designing energetic covalent organic frameworks for stabilizing high-energy compounds

As an emerging high-energy compound,3-nitro-1,2,4-triazol-5-one(NTO)is used in military explosives and rocket propellants.However,the strong acidic corrosion of NTO,and the high sensitivity and poor thermostability of its salts,severely restrict their practical applications.Therefore,a novel strategy to design and construct energetic covalent organic frameworks(COFs)is proposed in this study.We have successfully prepared a two-dimensional crystalline energetic COF(named ECOF-1)assembled from triaminoguanidine salt,in which NTO anions are trapped in the porous framework via the ionic interaction and hydrogen bonds.The results show that ECOF-1 exhibits superior thermal stability than energetic salt of NTO.It also exhibits insensitivity and excellent heat of detonation of 7,971.71 kJ·kg−1.ECOF-1 greatly inhibits the corrosiveness of NTO.In prospect,energetic COFs are promising as a functional platform to design high-energy and insensitive energetic materials.

Frustrated Lewis pairs in situ formation in B-based porous aromatic frameworks for efficient o-phenylenediamine cyclization

Benzimidazoles are very important chemical materials in the pharmaceutical industry,and the most common synthetic route is cyclization of o-phenylenediamine with carbon sources,in which utilization of inexpensive and abundant CO_(2)as C1 source is very impressive.Porous aromatic frameworks(PAFs)with highly desired skeletons have attracted great attentions in gas capture and catalysis.Herein,B-based PAF-165 and PAF-166 are designed and synthesized via Friedel-Crafts alkylation reaction,which present high surface areas as well as high stability.Benefiting from the abundant electron-deficient B centers,both PAFs exhibit excellent selective CO_(2)adsorption abilities.The presence of sterically hindered B units in PAFs can act as Lewis acid active sites for the frustrated Lewis pairs(FLPs)in situ formation with ophenylenediamine,thus promoting the synthesis of benzimidazole.The optimal reaction conditions for o-phenylenediamine cyclization with PAF catalysts are explored,and the reaction mechanism is also proposed.This work provides feasible ideas for incorporating FLPs within porous materials as reusable heterogeneous catalysts for CO_(2)capture and conversion.

Continuous polypyrrole nanotubes encapsulated Co_(3)O_(4)nanoparticles with oxygen vacancies and electron transport channels boosting peroxymonosulfate activation

Co_(3)O_(4)particles are promising heterogeneous catalysts for peroxymonosulfate(PMS)activation;whereas they still surfer from the extensive agglomeration,serious Co leaching,poor electronic conductivity,and difficult recovery.Herein,a novel hybrid nanoarchitectonic constructed by encapsulating Co_(3)O_(4)nanoparticles into continuous polypyrrole(PPy)nanotubes(Co_(3)O_(4)@PPy hybrids)was developed using electrospun fibers as the templates,which boosted the catalytic degradation toward tetracycline(TC).The continuous polypyrrole nanotubes could provide the confined spaces,offer effective electron transfer pathway,suppress cobalt ion loss,facilitate the oxygen vacancy(Ovac)formation,and accelerate the Co^(2+)/Co^(3+)cycles.Co_(3)O_(4)@PPy hybrids thereby exhibited a remarkably enhanced catalytic activity with the TC degradation efficiency of 97.2%(kobs=0.244 min^(−1))within 20 min and total organic carbon(TOC)removal rate of 66.8%.Furthermore,the recycle test,real natural water treatment,and fluidized-column catalytic experiments indicated the potential of Co_(3)O_(4)@PPy hybrids in the practical large-scale applications.

A Three-Dimensional Silicon-Diacetylene Porous Organic Radical Polymer

Radical-containing porous organic polymers(POPs)have drawn great interest in various applications.However,the synthesis of radical POPs remains challenging due to the unstable nature of organic radicals.Here,a persistent and stable three-dimensional silicon-diacetylene porous organic radical polymer was synthesized via a classic Eglinton homocoupling reaction of tetraethynylsilane.The presence of carbon radicals in this material was confirmed by electron paramagnetic resonance,and its paramagnetic behavior was analyzed by a superconducting quantum interference device.This unique material has a low-lying lowest unoccupied molecular orbital(LUMO)energy level(−5.47 eV)and a small energy gap(ca.1.46 eV),which shows long-term cycling stability and excellent rate capability as an anode material for lithium-ion batteries,demonstrating potential application in energy fields.

Porous organic polymers: a progress report in China

Porous organic polymers(POPs) are porous materials composed of light elements such as C, H, N, and O. The benign characters,including large surface area, good physical and chemical stability, well-defined chemical composition, wide ranges of monomer selection, and strong designability, have made POPs one of the frontiers in materials research. In this review, we discussed the design and synthesis of various POP materials that mainly led by Chinese scientists, including conjugated microporous polymers(CMPs), porous aromatic frameworks(PAFs), and hypercrosslinked porous polymers(HCPs), as well as crystalline POPs comprised of covalent organic frameworks(COFs) and a special class of COFs with triazine rings, covalent triazine frameworks(CTFs), and supramolecular organic frameworks(SOFs), and sorted out their main applications in adsorption, separation,catalysis, and electrochemistry fields.

Rational design of new in situ reduction of Ni(II)catalytic system for low-cost and large-scale preparation of porous aromatic frameworks

Porous aromatic framework 1(PAF-1)is an extremely representative nanoporous organic framework owing to its high stability and exceptionally high surface area.Currently,the synthesis of PAF-1 is catalyzed by the Ni(COD)2/COD/bpy system,suffering from great instability and high cost.Herein,we developed an in situ reduction of the Ni(II)catalytic system to synthesize PAF-1 in low cost and high yield.The active Ni(0)species produced from the NiCl_(2)/bpy/NaI/Mg catalyst system can effectively catalyze homocoupling of tetrakis(4-bromophenyl)methane at the room temperature to form PAF-1 with high Brunauer-Emmett-Teller(BET)-specific surface area up to 4948 m^(2) g^(−1)(Langmuir surface area,6785 m2 g−1).The possible halogen exchange and dehalogenation coupling mechanisms for this new catalytic process in PAF's synthesis are discussed in detail.The efficiency and universality of this innovative catalyst system have also been demonstrated in other PAFs'synthesis.This work provides a cheap,facile,and efficient method for scalable synthesis of PAFs and explores their application for high-pressure storage of Xe and Kr.

High energy and insensitive explosives based on energetic porous aromatic frameworks

The design and synthesis of energetic materials with a compatibility of high energy and insensitivity have always been the research fronts in military and civilian fields.Considering excellent performances of porous organic frameworks and the lack of research in the field of energetic materials,in this study,a new concept named energetic porous aromatic frameworks(EPAFs)is proposed.The strategy of coating high energy explosives such as 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20)and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX)in the EPAFs by wet-infiltration method has successfully realized the assembly of target energetic composite materials.The results show that the 75 wt.%CL-20@EPAF-1 possesses the safer impact sensitivity of 31.4 J than that of CL-20(4.0 J).Notably,for 75 wt.%CL-20@EPAF-1,in addition to the superior detonation performances of the detonation velocity(8,761 m·s^(-1))and detonation pressure(31.27 GPa),the synergistic effect of the nitrogen-rich EPAFs and the nitramines high energy explosives results in a higher heat of detonation that surpasses the most of pristine high explosives and reported novel energetic materials.In prospect,energetic porous aromatic frameworks could be a promising and inspiring strategy to build high energy insensitive energetic materials.

Two flexible cationic metal-organic frameworks with remarkable stability for CO_(2)/CH4 separation

Cationic azole-based metal-organic frameworks(MOFs)with remarkable stability and unique pore environment have aroused great research interests.Meanwhile,flexible MOFs which can undergo pore-structure changes upon exposure to external stimuli are ideal materials for gas separation.However,introducing flexibility into the framework of cationic azole-based MOFs is rarely reported.Herein,we synthesized two stable isomorphic cationic MOFs(M-btz-as,M=Co,Ni)based on a linear azole ligand.After activated at high temperature under vacuum,M-btz-ht(M=Co,Ni)were obtained and both MOFs exhibited flexible features in which Co-btz is more flexible than Ni-btz.Different solvent-mediated activation methods were employed to explore their effects on structural flexibility and produced MOFs with different phases.Continuous phase transformation of Co-btz-e was verified by powder X-ray diffraction.In addition,these MOF phases possessed different gas separation abilities affected by their flexible frameworks,and Co-btz-ht exhibited the highest CO_(2)/CH4 separation ability.

Fine-tuned mesoporous covalent organic frameworks for highly efficient low molecular-weight proteins separation

Covalent organic frameworks(COFs)are prominent porous materials for molecules separation due to their desirable structures.However,very few COFs are reported for the separation of macromolecules such as low molecular-weight(MW)proteins.Here,two stable mesoporous COFs(Azo-COF and Tp-COF)with highly crystallized frameworks are synthesized,and their pore sizes are slightly-regulated via elaborate selection of pyrene knots and amino linkages.Benefiting from the pore size difference less than 4 ?,the tandem utilization of these two COFs exhibits efficiently size-selective separation ability towards low MW proteins cytochrome c and myoglobin with small MW difference of 2 kDa,in which protein adsorption possibilities are verified by computational calculations together with confocal laser scanning microscopy(CLSM).Furthermore,a simple COF-based separation device is designed and prepared to achieve effective and low-consumption proteins separation.This work has offered an optimized synthetic strategy for fine-tuned mesoporous COFs and expanded their applications on macromolecules separation.

以多孔芳香骨架材料PAF-1作为对映选择性有机催化的超稳定固载平台（英文）

PAF-1是最著名的多孔芳香骨架材料(PAF),它拥有许多优异的性质并且可被用于多个领域.由高密度的苯环组成的PAF-1材料拥有刚性结构和亲脂性孔道,非常适合用作有机催化的平台.但是迄今为止,尚未有将其应用到对映选择性有机催化的报道.本论文以PAF-1为固载平台,将手性脯氨酰胺催化位点通过一系列后修饰的方法固载到PAF-1的骨架上,得到了新颖的手性固载催化剂PAF-1-NHPro.PAF-1-NHPro在催化对硝基苯甲醛和环己酮的Aldol反应的过程中表现出了优良的非对映选择性和对映选择性以及良好的可回收利用性.本工作展现了PAF材料在非均相对映选择性有机催化领域的应用前景.