Actuation design for high‐performance shape memory polyurethanes

A series of shape memory polyurethanes were synthesized from poly(tetramethylene glycol), 4,4‐methylene diphenyl diisocyanate, and 1,3‐butanediol. The prepolymers with different molecular weights (M_c) were capped with 2‐hydroxyl ethylacrylate or 3‐aminopropyltriethoxysilane (APTES) and crosslinked by UV curing or a sol–gel reaction. Variations of the crosslinker functionality (f), subchain density (N), and hard segment content (HSC) produced systematic variations of the glass transition temperature (6–45 °C), accompanied by changes in the mechanical, dynamic mechanical and shape memory properties. More than 95% of shape fixity and 98% of shape recovery up to the fourth cycles were obtained with APTES crosslinked 3000M_c with 30% of HSC. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1473–1479     

The band alignment at CdS/Cu2ZnSnSe4 heterojunction interface

Band alignment at CdS/Cu₂ZnSnSe₄ heterojunction interface is studied by X‐ray photoemission spectroscopy. The Cu₂ZnSnSe₄ thin films are prepared by selenization of electrodeposited Cu‐Zn‐Sn precursors. CdS overlayers with different thickness are sequentially grown on the Cu₂ZnSnSe₄ substrate by pulsed laser deposition process. Photoemission spectra are obtained before and after each growth to study the conduction and valence band offsets at the heterojunction interface. The determined conduction band offset of 0.34 eV indicates a spike‐like ‘type I’ band alignment at CdS/Cu₂ZnSnSe₄ interface. The spike will avoid interface recombination, and it is low enough that electron could transfer from the Cu₂ZnSnSe₄ layer to the buffer layer which is suitable for solar cell's fabrication. Copyright © 2012 John Wiley & Sons, Ltd.     

Influence of AC Electric Field on Macroscopic Network of Carbon Nanotubes in Polystyrene

CVD‐grown multiwall carbon nanotubes are dispersed in styrene monomer. During the polymerization of styrene, an AC electric field is applied to induce the CNTs to align along the electric field line to form a macroscopic nanotube network in polystyrene matrix. The dielectrophoresis force and the electric field redistribution at the CNTs apexes are responsible for alignment of the CNTs as well as bonding between the CNTs. Parameters such as field strength and nanotube weight fraction are varied. The results indicate that the macroscopic CNTs alignment along electric field direction can be observed only if the AC voltage reaches or is higher than certain values, and the higher the electric field frequency is, the more uniformly the CNTs align along electric field direction. In addition, nanotube concentration also affects the alignment of CNTs. According to the results of this study, the CNTs will align into a developed network in polystyrene matrix under a proper combination of three parameters of the electric field voltage, frequency, and the CNTs concentration.     

等离子体聚合及其聚合物的应用

本文着重综述了烃,含氮、氧的有机化合物,碳氟化合物以及有机硅化合物的等离子体聚合。同时还系统地介绍了等离子体聚合物在制备反渗透膜、分离膜、材料表面的涂层等方面的国内外的最新研究成果。     

Large-area periodic lead halide perovskite nanostructures for lenticular printing laser displays

Lenticular printing technique provides a promising way to realize stereoscopic displays,especially,when microscopic optical structures are integrated into light-emitting materials/devices.Here,we fabricated large-area periodic structures with a spatial resolution at a wavelength scale from hybrid perovskite materials via a space-confined solution growth method.It takes advantages of both high refractive index contrast and high luminescence brightness,which allows the optical modulation on not only the reflection of illumination,but also the light emission from hybrid perovskites.The distributed feedback within these periodic structures significantly improves the degree of polarization and directionality of laser actions while their threshold is also reduced.These findings enable us to present a prototype of lenticular printing laser displays that vary emission colors at different view angles,which may find applications in creating high-resolution and high-contrast holographical images.     

Cobalt and nitrogen atoms co-doped porous carbon for advanced electrical double-layer capacitors

Electrical double-laye r capacitors are widely concerned fo r their high power density,long cycling life and high cycling efficiency.However,their wide application is limited by their low energy density.In this study,we propose a simple yet environmental friendly method to synthesize cobalt and nitrogen atoms co-doped porous carbon(CoAT-NC) material.Cobalt atoms connected with primarily pyridinic nitrogen atoms can be uniformly dispersed in the amorphous carbon matrix,which is benefit for improving electrical conductivity and density of states of the carbon material.Therefore,an enhanced perfo rmance is expected when CoAT-NC is served as electrode in a supercapacitor device.CoAT-NC displays a good gravimetric capacitance of 160 F/g at 0.5 A/g combing with outstanding capacitance retention of 90% at an extremely high current density of 100 A/g in acid electrolyte.Furthermore,a good energy density of30 Wh/kg can be obtained in the organic electrolyte.     

Designed fabrication of mesoporous silica-templated self-assembled theranostic nanomedicines

Theranostic nanosystems that integrate diagnosis and therapy have garnered increasing attention for personalized medicine.The integration of the versatile nanoparticles to fabricate self-assembled theranostic nanomedicines becomes increasingly important in current medical research.Mesoporous silica nanoparticles(MSN)with their highly attractive physicochemical properties and favorable morphological attributes represent ideal templates for the controlled assembly and integration of functional nanomaterials to fabricate self-assembled theranostic nanomedicines.The rationally designed combination strategy and heterostructure will improve the overall bioavailability and preserve the unique property of each nanocomponent.In this review,the cutting-edge strategies for the designed fabrication of MSN-templated self-assembled nanomedicines are summarized.We categorize MSN-based nanomedicines by their unique heterostructures,including core-shell,yolk-shell,core-satellite,heterodimer and core-shell-satellite structures,and discuss the controlled assembly approaches as well as the intriguing applications for disease theranostics.Finally,a perspective on the challenges in the clinical translation of self-assembled theranostic nanomedicines is highlighted.     

疏水性低共熔溶剂液液微萃取/高效液相色谱法测定豆奶中三嗪类和苯脲类除草剂

该文建立了一种简单、高效的新型疏水性低共熔溶剂液液微萃取法,用于提取和富集市售包装豆奶中的三嗪类（阿特拉津、去草净）和苯脲类（灭草隆、绿麦隆）除草剂,并结合高效液相色谱对目标分析物进行分离和测定。以六氟异丙醇为氢键供体,四丁基氯化铵为氢键受体,按照不同摩尔比制备了一系列疏水性低共熔溶剂,并对影响萃取效果的实验条件进行了优化,包括低共熔溶剂的种类及用量、氯化钠用量、涡旋时间、pH值和温度。结果表明,在最佳实验条件下,4种目标物在1.00～500.00 μg/L范围内具有良好的线性关系（r ≥ 0.998 4）,检出限和定量下限分别为0.56～0.95 μg/L和1.87～3.16 μg/L,日内和日间相对标准偏差（RSD）分别为0.28%～2.0%和2.1%～7.5%,加标回收率为86.4%～117%。该方法具有操作简单快速、萃取时间短、试剂用量少和实验成本低等优点,可用于市售包装豆奶中三嗪类和苯脲类除草剂的分析检测。     

Hydrolytic Enzyme of Cellulose for Complex Formulation Applied Research

To improve the enzymatic hydrolytic efficiency and reduce the supplementation of enzymes, the mixture designed experimental approach was used to optimize the composition of enzyme mixture and promote the hydrolysis of ball-milled corn stover. From the experimental results, a synergistic effect was found when combinations of the three enzymes, two kinds of cellulases and a kind of xylanase, were used. The optimal hydrolysis of pretreated corn stover accorded with enzymes activity ration of FPU/CMCase/β-glucosidase/xylanase = 4.4:1:75:829, and the hydrolysis efficiency of corn stover increased significantly compared with using individual enzyme. The results indicated that the mixture design experiment could be an effective tool for optimized enzyme mixture for lignocellulose hydrolysis.     

A Study of PbTiO3 Crystallization in Pure and Composite Nanopowders Prepared by the Sol-Gel Technique

Summary.  In this investigation the crystallization of PbTiO₃ upon annealing of pure nanopowders and PbTiO₃–SiO₂ (1:1 v/v) nanocomposite powders prepared by the sol-gel technique was studied. Using X-ray diffraction phase analysis, the start of PbTiO₃ crystallization in pure PbTiO₃ powders was detected at 400°C. Distinct crystallization of PbTiO₃ in PbTiO₃–SiO₂ nanocomposites starts at 700°C, whereas SiO₂ remains amorphous. There are indications that an interface interaction between the PbTiO₃ and the SiO₂ phase plays an important role in hindering the crystallization of PbTiO₃. The particle size (size of coherently scattering regions) was estimated from the broadening of the X-ray diffraction line profiles. The average size of PbTiO₃ nanocrystallites increases with temperature and time of annealing, the influence of temperature being more significant than that of the annealing time. Differential scanning calorimetry confirmed the results of the X-ray diffraction with respect to the start of the crystallization. Laser beam scattering and scanning electron microscopy provided the statistical distribution of the grain size and the morphology of the powder grains, showing that each grain of the powders contains several nanocrystallites (coherently scattering regions). Received October 4, 2001. Accepted (revised) December 14, 2001