2.5 THz量子级联激光器的研制

基于束缚态到连续态跃迁有源区能带结构,实现了2.5 THz量子级联激光器的连续波工作。激光器的输出频率随电流可在2.45~2.47 THz之间可调,在连续波工作模式下的最高输出功率大于6.0 mW,最高连续波工作温度为60 K,阈值电流密度为120 A/cm2,经Si透镜整形后的输出光斑为高斯分布。     

吸收式光纤温度传感器的研究

提出了一种利用半导体光吸收谱随温度变化原理设计的半导体吸收式光纤温度传感器.该传感器用GaAs晶片作为温度敏感元件,以光纤作为传光介质,发光二极管作为光源,光电管作为光电转换器件.利用双光束补偿原理,消除了由于光源不稳定产生的干扰.研制出的光纤传感器具有体积小,结构简单,抗电磁干扰,灵敏度高等优点.实验表明:该传感器在－20℃~85℃温度范围内可以达到0.1℃的准确度,可以实现强电磁干扰下的高空飞行器内环境温度的测量.为进一步实现光传飞控系统中的温度测控奠定了基础.     

衍射光栅的傅里叶分析方法

本文用衍射理论中的傅里叶分析方法,分析光栅在各种不同情况下的夫琅和费衍射现象中,其衍射屏上的复振幅分布、光强分布及频谱分布的规律。对于衍射光栅的应用具有指导意义。     

离焦散斑错位干涉术的逐点滤波分析与应用

通过相关计算,分析了离焦散斑错位干涉术的逐步滤波方法,得到了杨氏条纹的形成及分布特性。讨论了逐点滤波法的实用意义并给出了在缺陷检测中的应用实例。     

Catechol‐Functionalized Polyolefins

The incorporation of comonomers during ethylene polymerization can efficiently modulate important material properties of the polyolefins. Utilizing bioresourced comonomers for the generation of high‐performance polyolefin materials is attractive from a sustainability point of view. In this contribution, bioresourced eugenol and related comonomers were incorporated into polyolefins through palladium‐catalyzed copolymerization and terpolymerization reactions. Importantly, high‐molecular‐weight catechol‐functionalized polyolefins can be generated. The introduction of different metal ions induces efficient interactions with the incorporated catechol groups, leading to enhanced mechanical properties and self‐healing properties. Moreover, the catechol functionality can greatly improve other properties such as surface properties, adhesion properties, and compatibilizing properties. The catechol‐functionalized polyolefin was demonstrated as a versatile platform polymer for accessing various materials with dramatically different properties.     

Redox‐Controlled Olefin (Co)Polymerization Catalyzed by Ferrocene‐Bridged Phosphine‐Sulfonate Palladium Complexes

The facile and reversible interconversion between neutral and oxidized forms of palladium complexes containing ferrocene‐bridged phosphine sulfonate ligands was demonstrated. The activity of these palladium complexes could be controlled using redox reagents during ethylene homopolymerization, ethylene/methyl acrylate copolymerization, and norbornene oligomerization. Specifically in norbornene oligomerization, the neutral complexes were not active at all whereas the oxidized counterparts showed appreciable activity. In situ switching between the neutral and oxidized forms resulted in an interesting “off” and “on” behavior in norbornene oligomerization. This work provides a new strategy to control the olefin polymerization process.     

Direct Synthesis of Functionalized High‐Molecular‐Weight Polyethylene by Copolymerization of Ethylene with Polar Monomers

The introduction of even a small amount of polar functional groups into polyolefins could excise great control over important material properties. As the most direct and economic strategy, the transition‐metal‐catalyzed copolymerization of olefins with polar, functionalized monomers represents one of the biggest challenges in this field. The presence of polar monomers usually dramatically reduces the catalytic activity and copolymer molecular weight (to the level of thousands or even hundreds Da), rendering the copolymerization process and the copolymer materials far from ideal for industrial applications. In this contribution, we demonstrate that these obstacles can be addressed through rational catalyst design. Copolymers with highly linear microstructures, high melting temperatures, and very high molecular weights (close to or above 1 000 000 Da) were generated. The direct synthesis of polar functionalized high‐molecular‐weight polyethylene was thus achieved.     

Facile Synthesis of β‐Diketone Alcohols for Combined Functionality: Initiation,Catalysis, and Luminescence

Primary alcohol‐functionalized β‐diketones (bdks) are successfully synthesized via facile one‐step Claisen condensation between aromatic monoketones and ε‐caprolactone (ε‐CL). To demonstrate application potentials, these bdk alcohols are used to chelate with various Lewis acids, including Tb (III), Eu (III), and B (III). It is discovered that the resulting Tb (III) and Eu (III) diketonate complexes can serve as both catalysts and initiators for ring‐opening polymerization (ROP) under solvent‐free conditions, using lactide monomer as an example. The polylactides (PLAs) thus obtained exhibit luminescence properties characteristic of Tb (III) and Eu (III), respectively. On the other hand, boron‐chelated diketone can initiate ROP of lactide in the presence of Sn(oct)₂, and affords a PLA material with dual‐emission, i.e., fluorescence and room temperature phosphorescence. The synthesis described here represents a shortcut for the preparation of bdk‐based macroligands and subsequent functional materials.

     

Ni catalyzed ethylene copolymerization with polar monomers

<正>Introduction of polar comonomers into polyethylene is highly challenging, paving the way to tuning the copolymers’ mechanical properties, adhesion/compatibility, and biodegradability. Polar-group tolerant single-site palladium and, more tempting, nickel-based catalysts have demonstrated promising reactivities in the ethylene copolymerization with polar comonomers via coordination/insertion mechanism, providing tighter control of polymer micro-