A Biologically Muscle-Inspired Polyurethane with Super-Tough,Thermal Reparable and Self-Healing Capabilities for Stretchable Electronics

Polymeric elastomers play an increasingly important role in the development of stretchable electronics. A highly demanded elastic matrix is preferred to own not only excellent mechanical properties, but also additional features like high toughness and fast self-healing. Here, a polyurethane (DA-PU) is synthesized with donor and acceptor groups alternately distributed along the main chain to achieve both intra-chain and inter-chain donor-acceptor self-assembly, which endow the polyurethane with toughness, self-healing, and, more interestingly, thermal repair, like human muscle. In detail, DA-PU exhibits an amazing mechanical performance with elongation at break of 1900% and toughness of 175.9 MJ m⁻³. Moreover, it shows remarkable anti-fatigue and anti-stress relaxation properties as manifested by cyclic tensile and stress relaxation tests, respectively. Even in case of large strain deformation or long-time stretch, it can almost completely restore to original length by thermal repair at 60 °C in 60 s. The self-healing speed of DA-PU is gradually enhanced with the increasing temperature, and can be 1.0–6.15 µm min⁻¹ from 60 to 80 °C. At last, a stretchable and self-healable capacitive sensor is constructed and evaluated to prove that DA-PU matrix can ensure the stability of electronics even after critical deformation and cut off.     

受主杂质Mn对（Ba,Pb）TiO3系高温PTC热敏陶瓷的影响

本文研究了(Ba,Pb)TiO_3系高温PTC半导体陶瓷中半导化与其烧结工艺、铅空位、钡空位和施、受主杂质等相互之间的关系。着重分析讨论了引入受主杂质Mn对材料的半导化的影响,并采用复合缺陷模型自洽地解释了实验现象。     

生色基团插层锌铝水滑石的制备和性质

以层状锌铝水滑石为主体, 在乙二醇介质中, 通过离子交换法, 将一对具有给体－受体性质的生色团香豆素-3-甲酸(3-CCA)与9-蒽甲酸(9-ACA)共插入到层状锌铝水滑石层间, 组装得到晶体结构良好的共插层类水滑石, 且通过控制离子交换的时间、温度、客体投料比, 可制得一系列具有不同摩尔比客体的共插层产物. 产物采用XRD、IR、TG-DTA等测试技术进行结构表征, 采用UV-Vis吸收光谱和荧光光谱研究其光谱特性. 结果表明, 给体受体进入层间后, 不仅客体与主体层板存在静电力和氢键相互作用, 而且在限域空间内有利于客体之间的相互作用, 从而产生了给体受体间的能量转移过程.     

Characterization of noncovalent interactions between 6-propionyl-2-dimethylaminonaphthalene (PRODAN) and dissolved fulvic and humic acids

Noncovalent interactions between the fluorescent probe 6-propionyl-2-dimethylaminonaphthalene (PRODAN) and dissolved Norman Landfill leachate fulvic acid, Suwannee River fulvic acid, Suwannee River humic acid, and Leonardite humic acid were examined as a function of pH, fulvic and humic acid (FA and HA) concentration, and solvent polarity using steady-state fluorescence spectroscopy. Static quenching processes, as indicated by linear Stern-Volmer plots and high K(d) values, were positively correlated with the % aromaticity of the FA and HAs, as well as with solution pH. Results illustrate that for FA molecules with relatively low % aromaticity values, solvophobic interactions between PRODAN and FA are the primary interaction mode. For HA molecules with higher % aromaticity, PRODAN engages in both solvophobic interactions and pi-pi interactions, in particular electron donor-acceptor interactions, via condensed aromatic, electron-accepting moieties inherent within HA molecules. Experiments modifying solvent polarity demonstrated that protonation of carboxylic acid functional groups at low pH ( approximately 4) increased the hydrophobicity of the dissolved FA and HA molecules, thereby enhancing noncovalent interactions with PRODAN through increased solvophobic forces.     

All-carbon N-heterocyclic Carbene-catalyzed (3+2) Annulation using Donor-Acceptor Cyclopropanes

Donor-acceptor cyclopropanes are known to serve as dipole precursors capable of engaging in (3+2) annulations with electron-deficient π-systems. In 2013, the reaction of donor-acceptor cyclopropanes with α,β-unsaturated acyl fluorides in an all-carbon (3+2) annulation was discovered. The reaction proceeds in good yields using the IMes NHC to provide diastereomerically pure β-lactone-fused cyclopentanes bearing four contiguous stereocentres. Subsequent studies demonstrated that N-t-butyl substituted homochiral morpholinone NHCs allowed the reaction to be achieved in up to 98 % ee. In this account, a background to this reaction is introduced, along with a complete account of the strengths, limitations and challenges encountered while developing this chemistry.     

一种异靛蓝衍生半导体的合成、表征和OTFT应用

以4-癸基十六烷基溴和6-溴二氢吲哚-2,3-二酮为原料,将4-癸基十六烷基侧链引入到(3E,7E)-3,7-双(2-氧代二氢吲哚-3-亚基)苯并[1,2-b:4,5-b']二呋喃-2,6(3H,7H)-二酮(IBDF)中合成了IBDF-26,再与(E)-1,2-双(三丁基甲锡烷基)乙烯通过Stille偶合制备了基于异靛蓝衍生大稠环聚合物的半导体PIBDFV-26。采用TGA、DSC、UV、CV、XRD、AFM对PIBDFV-26的性能、结构、形貌进行了表征。结果表明,基于异靛蓝大稠环的半导体PIBDFV-26在三氯乙烯(TCE)中的溶解性良好,具有良好的热稳定性,HOMO/LUMO能级为–5.96eV/–4.62eV,光学帯隙为1.34eV。XRD结果表明,聚合物链沿边沿取向形成层状晶体结构,层间距为2.55×10~(–6) mm,π–π堆积距离为3.46×10~(–7) mm。AFM显示,退火处理的PIBDFV-26薄膜表面含有纳米级的晶状颗粒。对PIBDFV-26组装的有机薄膜晶体管(OTFT)器件进行了测试,结果显示OTFT器件表现出电子传输(negative,n)型沟道的电荷传输特性。150℃退火处理的聚合物薄膜的平均电子迁移率为0.13 cm~2/(V?s)。     

Donor-Acceptor Charge Complex Formation in Barium Titanate Ceramics: Role of Firing Atmosphere

BaTiO₃ ceramics containing Mn acceptors and various Mo, W and Nb donor dopants have been fired in reducing atmosphere and re-oxidized in N₂/O₂. In single Mn-doped ceramics, Mn²⁺ is completely oxidized to Mn³⁺; in N₂ containing 50 ppm O₂ at T > 800°C. Changes of the Curie point and sample length under reduction and re-oxidation have been detected using dielectric and thermomechanical measurements. Charge compensation and complex formation between acceptors and donors have been observed. In donor-acceptor charge complexes, Mn²⁺ cannot be oxidized.     

The Evolution of Fe-catalyzed Nucleophilic Activation of Acceptor-substituted Vinyl- and Arylcyclopropanes

Acceptor-substituted vinyl- (VCP) and arylcyclopropanes (ACP) are reactive substrates for nucleophilic activation using Bu₄N[Fe(CO)₃(NO)] (TBA[Fe]). In this account, the application of this catalytic strategy in traceless allylic substitution, [3+2]-cycloaddition, and Cloke-Wilson rearrangement will be presented. Additional information, derived from detailed spectroscopic and theoretical investigations, is discussed. These results not only lead to a deeper understanding of the reactivity of the catalyst in VCP and ACP activation, but also set the stage for a new type of catalyst activation using photochemical irradiation at 415 nm.     

VOF方法中几种界面重构技术的比较

通过理论分析和数值模拟，比较了界面跟踪技术中VOF方法的三种界面重构技术。利用三种流场，即平移场、旋转场和剪切场对它们进行了数值模拟和比较。结果表明，除有些尖角会被少许抹平外，PLIC方法无论在界面的精细度上还是在锐利性上都要好于前两，而FLAIR方法次之。     

Contributions of Ernest Wenkert to the Use of Cyclopropanes in Synthesis – Impact,Reflections, and Recollections

This essay describes Ernest Wenkert's contributions to the chemistry of cyclopropanes and their use in synthesis. The impact of his work on the careers of others, especially including the development of cyclopropane-based research in the Hudlicky group, is addressed, along with reflections on his mentorship. Personal recollections from some of his past students are provided at the end of the article.