Non-spherical Janus microgels driven by thiolated DNA interactions

Janus poly (N-isopropylacrylamide)-co-acrylic acid/Au microgels that resemble a “snowman”, “dumbbell”, and an “abalone” were prepared by thermally evaporating a layer of Au on half of the microgel surface, followed by exposure to thiolated single-stranded DNA with complementary sequences. We hypothesize that when the complementary single-stranded DNA attached to the Au forms the more stable double strand, the Au reorganizes on the microgel surface, yielding the observed unique Janus particle structures.     

双面粒子的制备及应用研究进展

从聚合物、无机物、聚合物／无机物三方面综述了近年来双面粒子的制备及应用研究进展。     

Janus gold nanoparticle with bicompartment polymer brushes templated by polymer single crystals

Janus particles have attracted increasing attention from the communities of materials science, chemistry, physics and biology. While large size Janus particles are readily achieved, synthesizing Janus nanoparticles (JNP) with diameters smaller than ∼20 nm remains a challenging task. In this article, we report a systematic study on growing polymer brushes on polymer-single-crystal-immobilized 6 and 15 nm diameter gold nanoparticles (AuNPs) using atom transfer radical polymerization. JNPs with bicompartment polymer brushes, such as poly(ethylene oxide) (PEO)/poly(methyl methacrylate), PEO/poly(tert-butyl acrylate), and PEO/poly(acrylic acid), were synthesized. The grafting densities can be carefully controlled. The Janus feature of these particles was confirmed using both platinum nanoparticle decoration and UV/Vis spectroscopy analysis. The surface plasmon resonance absorbance of Janus particles exhibited a blue shift compared with that of symmetric AuNPs with either homopolymer or mixed polymer brushes. This work demonstrated that using polymer single crystal as the templates, small size (<20 nm diameter) JNPs having bicompartment polymer brushes can be readily obtained. The ability to tune grafting density and molecular weight of polymer brushes can lead to controlled particle amphiphilicity.     

功能性Janus纳米颗粒的研究进展

Janus纳米颗粒是一类在空间或物化性质上各向异性的纳米材料,因其独特的性质和在功能涂层、环境、催化、生物医学等领域的应用而受到广泛关注。不同纳米颗粒的侧边分布为定制具备丰富功能的Janus纳米颗粒提供了一个灵活的平台,与传统均质纳米颗粒相比,功能性Janus纳米颗粒凭借两种功能或多种功能的结合拓展了更多的新兴应用领域。该文重点讨论了磁响应性、光催化性、非对称浸润性及自驱动性等功能性Janus纳米颗粒的制备策略;同时介绍了功能性Janus纳米颗粒的应用领域,并对其存在的问题进行分析讨论;最后,对功能性Janus纳米颗粒合成和应用前景进行了展望。     

Preparation and characteristics of highly porous BN-Si3N4 composite ceramics by combustion synthesis

Nitride based ceramics are considered as a kind of promising material for structural and functional integration due to their robust structure, extreme environmental resistance and electromagnetically transparency. It is still challenging to prepare nitride based ceramics with homogeneous and controllable microstructure because of their low self-diffusion coefficient and difficulty in sintering. Here, we developed a gelcasting-SHS process by combining gelcasting forming and self-propagating high temperature synthesis (SHS) for the preparation of porous BN-Si₃N₄ composite ceramics. First, carbon residue problem in the gelcasting -SHS process was studied. Based on the result, porous BN-Si₃N₄ composite ceramics with high porosity (69.42 ~ 86.48%), high strength (21.7 ~ 81.0 MPa) and low dielectric constants (1.42 ~ 2.87) were synthesized. In addition, the thermal shock resistance of porous BN-Si₃N₄ composite ceramics until 1000 ℃ was evaluated.     

Janus particle amphiphilicity and capillary interactions at a fluid interface

Studying the behavior of anisotropic particles at fluid interfaces is a rapidly expanding field, as understanding how the introduced anisotropy affects the resulting properties is essential in the engineering of interfacial systems. Surface anisotropic particles, also known as Janus particles (JPs), offer new possibilities for novel applications due to their amphiphilicity and stronger binding to fluid interfaces compared to homogeneous particles. Introducing surface anisotropy creates complexity as the orientation of interfacially bound particles affects interparticle interactions, a contributing factor to the microstructure formation. In this work, we have investigated the microstructure of JP monolayers formed at the air–water interface using particles with different degrees of amphiphilicity and examined the response of the networks to applied compressions. Our findings demonstrate that JPs amphiphilicity is a crucial factor governing their orientation at the interface, which in turn dictates the complexity of the capillary interactions present and the mechanical properties of the ensuing networks.     

基于模板法制备两亲性Janus纳米粒子及其应用进展

Janus粒子是同一粒子中含有两种不同化学组成的非对称结构,其中两亲性Janus粒子是在对立面分别含有亲水基、疏水基两种不同化学基团,作为一种新型纳米材料受到广泛的关注。该文综述了模板法制备不对称结构的两亲性Janus粒子以及其应用领域,包括硬模板法、软模板法、牺牲模板法以及无模板法;综述了两亲性Janus粒子在表面活性剂、牙科粘合剂、微胶囊、功能涂层、催化剂以及生物传感器等方面的研究进展。     

Engineered Smart Textiles and Janus Microparticles for Diverse Functional Industrial Applications

Janus materials are biomimetically inspired systems with two or more functional properties arising as paramount materials for utilization in different fields like Medical, Protective clothing etc. Janus particles can be in different forms like capsule, fiber, nano cage, disc, nano film etc. which are amalgamated with fabric by different processes. Based on the fabrication and constituent elements, Janus materials can be fabricated by incorporating multiple properties like fire-retardancy, catalytic property, thermal regulation etc. This review article enumerates the numerous industrial applications of the Janus fabrics and simultaneously outlines the extensive methodologies utilized for engineering of the Janus fabrics.     

Creating polymer templates and their use in the in-situ synthesis of biodegradable composite networks

A biodegradable polyethyleneoxide–polycaprolactone–polyethyleneoxide (PEO–PCL–PEO or PECE) triblock polymer was synthesized as a structure-directing agent for high-surface area silica formation. Systematic end-group functionalization of the triblock polymer, prior to its use as a structure-directing agent for high-surface area silica growth, imparts an additional reactive function that is exploited to grow a continuous organic phase within and around the silica particles. Hence, the biodegradable triblock also acts as a macromer whose dual function leads to in-situ generation of intimately mixed biopolymer/nanoporous–silica composite networks. This composite can be both biodegradable and biocompatible, and the modulus is comparable to other non-biodegradable materials.     

微孔-中孔复合分子筛的合成研究进展

概述了最近几年引起人们广泛关注的微孔-中孔复合分子筛的合成情况,重点介绍了不同复合模式的微孔-中孔复合分子筛的合成方法,包括单模板剂法、双模板剂法、附晶生长法、孔壁晶化法、碱处理法、微孔沸石硅源法等一系列方法,分析了各种合成方法的优点。从目前已取得的研究结果看,附晶生长法和碱处理法值得进一步关注。     

两亲Janus纳米片的制备及胶体与界面性质研究进展

该文首先综述了两亲Janus纳米片制备方法的研究进展，包括界面保护法、乳液界面自组装溶胶-凝胶法、模板辅助溶胶-凝胶法以及嵌段共聚物自组装法。接着，系统介绍了两亲Janus纳米片在水溶液中的胶体特性及其在油水体系中的界面特性。最后，简要介绍了两亲Janus纳米片的应用领域，并对未来两亲Janus纳米片制备方法和胶体与界面特性的研究方向进行了展望。     

Hydrophobic/Hydrophilic Cooperative Janus Branched Polymer Fibers with Controllable Length and Density of Nanobranches

The fabrication of a fiber with multilevel micro‐/nanostructures is still a great challenge. Here, a newly structured polymer fiber, which possesses both a hydrophobic/hydrophilic cooperative Janus stem and nanosized branches with controllable length and density, is developed via a microfluidic‐electrospinning technology for the first time. Both the length and density of the branches on the fiber can be controlled by changing the electrical conductivity of the inner phase of poly(vinyl alcohol) solution or the applied voltage. The mechanical analytic model reveals that when the coulomb force between surface charge of continuous phase and volume charge of dispersed phase, which is raised with the electrical conductivity of the inner phase or the applied voltage increasing, is greater than surface tension of continuous phase, the branches are formed; simultaneously, the Janus structure is generated through both the electrostatic repulsion and phase separation.     

Double in-situ synthesis of polyacrylate/nano-TiO2 composite latex

Polyacrylate/nano-TiO₂ composite latex was prepared via double in-situ polymerization using acrylamide (AM), vinyl acetate (VAc), butyl acrylate (BA) and methyl methacrylate (MMA) as monomers, tetrabutyl titanate (Ti(OBu)₄) as precursor of TiO₂. The morphology, structure and distribution of composite latex were characterized by Transmission Electron Microscope (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Dynamic Light Scattering (DLS) and X-Ray Diffraction (XRD). The thermal stability, anti-yellowing and antibacterial properties of composite latex were also investigated. The results showed that nano-TiO₂ consisted in polyacrylate latex and it was located on the surface of latex particles. The average particle size of polyacrylate/nano-TiO₂ composite latex was 156.6 nm, which was bigger than that of pure polyacrylate (125.1 nm). The introduction of nano-TiO₂ improved the thermal stability, anti-yellowing and antibacterial properties of the latex film. At last, the polyacrylate/nano-TiO₂ composite latex was applied in leather finishing. Compared with polyacrylate latex, the properties of the leather finished by polyacrylate/nano-TiO₂ composite latex were enhanced: water vapor permeability increased by 58% and water uptake decreased by 3.52%.     

Facile solvothermal synthesis of a graphene nanosheet-bismuth oxide composite and its electrochemical characteristics

This work demonstrates a novel and facile route for preparing graphene-based composites comprising of metal oxide nanoparticles and graphene. A graphene nanosheet-bismuth oxide composite as electrode materials of supercapacitors was firstly synthesized by thermally treating the graphene-bismuth composite, which was obtained through simultaneous solvothermal reduction of the colloidal dispersions of negatively charged graphene oxide sheets in N,N-dimethyl formamide (DMF) solution of bismuth cations at 180 °C. The morphology, composition, and microstructure of the composites together with pure graphite oxide, and graphene were characterized using powder X-ray diffraction (XRD), FT-IR, field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), thermogravimetry and differential thermogravimetry (TG-DTG). The electrochemical behaviors were measured by cyclic voltammogram (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS). The specific capacitance of 255 F g⁻¹ (based on composite) is obtained at a specific current of 1 A g⁻¹ as compared with 71 F g⁻¹ for pure graphene. The loaded-bismuth oxide achieves a specific capacitance as high as 757 F g⁻¹ even at 10 A g⁻¹. In addition, the graphene nanosheet-bismuth oxide composite electrode exhibits the excellent rate capability and well reversibility.     

Rashba Splitting and Electronic Valley Characteristics of Janus Sb and Bi Topological Monolayers

Janus Sb and Bi monolayers as a new class of 2D topological insulator materials, which could be fulfilled by asymmetrical functionalizations with methyl or hydroxyl, are demonstrated by first-principles spin–orbit coupling (SOC) electronic structure calculations to conflate nontrivial topology, Rashba splitting and valley-contrast circular dichroism. Cohesive energies and phonon frequency dispersion spectra indicate that all Janus Sb and Bi monolayers possess a structural stability in energetic statics but represent virtual acoustic phonon vibrations of the hydrogen atoms passivating on monolayer surfaces. Band structures of Janus Sb and Bi monolayers and their nanoribbons demonstrate they are nontrivial topological insulators. Rashba spin splitting at G point in Brillouin zone of Janus Bi monolayers arises from the strong SOC p_x and p_y orbitals of Bi bonding atoms together with the internal out-of-plane electric field caused by asymmetrical functionalization. Janus Sb and Bi monolayers render direct and indirect giant bandgaps, respectively, which are derived from the strong SOC p_x and p_y orbitals at band-valley Brillouin points K and K′ where valley-selective circular dichroism of spin valley Hall insulators is also exhibited.     

一锅法合成Janus纳米片及其对PS/TiO2复合材料的增容作用研究

利用一锅法合成了Janus纳米片（JNSs）,通过扫描电子显微镜（SEM）、电致冷X射线能谱仪（EDS）、动态混合流变仪、动态力学热分析仪（DMA）和万能材料试验机等对JNSs的表面形貌和化学成分进行了表征,考察了JNSs对聚苯乙烯/二氧化钛（PS/TiO₂）共混体系流变性能的影响,以及JNSs对PS/TiO₂复合材料动态力学性能、力学性能、表观形貌的影响,并对JNSs对复合材料的界面增容作用机理进行了探讨分析。结果表明,JNSs两面的粗糙程度不同,粗糙凹面含有氨基,光滑凸面含有双键;JNSs用作PS/TiO₂共混体系的相容剂时,能够增强界面作用力,改善无机粒子和有机聚合物的相容性;含0.5 份（质量份,下同）JNSs的PS/TiO₂复合材料的玻璃化转变温度（T_g）从PS的100 ℃提高到了107 ℃;同时,JNSs在外力作用下沿力的方向取向需要耗散能量,使得其拉伸强度较PS/TiO₂提高了13.43 %,断裂伸长率由12 %增加到了18 %。     

TiO2-PDVB Janus particles enhanced compatibility of titanium dioxide and recycled waste styrofoam

People are always puzzled by “white pollution” in recent decade. Recycling of waste styrofoam as a coating is a good sustainable solution to resolve this problem. However, the poor compatibility between inorganic additives and polymer hinders the application of recycled polystyrene. In this article, anisotropic Janus particles were used to increase the compatibility of titanium dioxide/waste styrofoam coatings. SEM results show that Janus particles can be anchored at the interface between styrofoam and titanium dioxide, increasing the dispersion of titanium dioxide, and improving the compatibility of inorganic particles and organic polymer. The glass-transition temperature of styrofoam coating increases from 77 °C to 89 °C in titanium dioxide/styrofoam contained 1 wt % of Janus particles, which certified that Janus particles have compatibilization on titanium dioxide/styrofoam coating. Attributing to this compatibilization, the tensile strength of titanium dioxide/styrofoam with 1 wt % of Janus particles rises about 45% compared with titanium dioxide/styrofoam. The yield stress, storage modulus, and viscosity of titanium dioxide/styrofoam contained 1 wt % of Janus particles are the smallest and the closest to Newtonian fluid. Janus particles used in the recycled styrofoam coating is benefit to expand the application of waste styrofoam and the new anisotropic Janus compatibilizer. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48691.     

（急）钴酞菁修饰两亲性Janus颗粒用于乳液界面光催化染料降解

本文制备了两亲性的雪人状Janus颗粒和钴酞菁催化剂,并成功将钴酞菁催化剂选择性地负载于Janus颗粒的亲水一侧,通过扫描电镜观察到分区明显且具有非对称结构的Janus颗粒,进一步通过XPS、EDS、红外光谱分析、热重分析等测试确定了颗粒的组分。将钴酞菁修饰的两亲性雪人状Janus颗粒同时作为固体颗粒乳化剂和界面催化剂,应用于多相体系中水溶性染料罗丹明B的光催化降解反应,考察了通风和光照、催化剂用量、染料初始浓度以及H₂O₂体积分数对催化效果的影响；通过紫外可见分光光度计观察染料的降解率,结果表明,该Janus颗粒催化剂对染料的催化降解率最高可达94.6%,相对于负载前催化剂展现出明显的催化优势,并且易于回收进行重复利用,循环5次仍保持良好的催化效率。     

Electrochemical synthesis of poly(o-anisidine)/chitosan composite on platinum and mild steel electrodes

In this study, poly(o-anisidine)/chitosan composite film was electrochemically synthesized on the platinum and mild steel electrodes. Electrochemical synthesis of the composite film was carried out by cyclic voltammetry technique. The synthesized composite film was characterized by FT-IR, UV–Vis, cyclic voltammetry, SEM and TGA. The SEM micrographs showed that the composite film homogeneously covered the surfaces of platinum and mild steel electrodes. The TGA results proved that the composite film does not degrade until 648 °C while the poly(o-anisidine) film is decomposed between 190 and 432 °C. Also, electrochemical studies showed that poly(o-anisidine) and the composite films have good stability and electroactivity.     

USY／SAPO-5复合分子筛催化合成长链烷基苯

采用水热合成法制备了一种USY/SAPO-5复合分子筛.通过XRD、IR、TEM等方法进行袁征,分析其晶型结构,证实形成了以USY为核,以SAPO-5为壳的复合分子筛结构.并将USY/SA-PO-5复合分子筛应用于苯和长链烯烃的烷基化反应,在n(苯):n(长链烯烃)=8:1,反应温度200℃,压力3.5 MPa,在此条件下长链烯烃的转化率可达99.2%,选择性也达到最好.