左旋异松蒎酮的合成

研究了以(－)-α-蒎烯为原料合成(－)-异松蒎酮的反应. 以四氢呋喃为溶剂, 硼氢化钠与三氟化硼乙醚溶液生成的硼烷不经分离直接与α-蒎烯发生反马氏加成反应, 生成二异松蒎烷基硼; 采用四水合过硼酸钠或NaOH-H₂O₂氧化硼氢化物得到(＋)-异松蒎醇, 产率为89.5%, 纯度97.4%, 熔点为55～56 ℃, 比旋光度 ＋28.31 (c 5.55, CH₃OH). 以钒磷氧化物为催化剂、双氧水作氧化剂, 将(＋)-异松蒎醇氧化得到(－)-异松蒎酮, 产率88% 以上, 纯度96.0%, 比旋光度为 －10.58 (c 5.51, CH₃OH). 采用IR, MS, ¹H NMR, ¹³C NMR等对(＋)-异松蒎醇和(－)-异松蒎酮结构进行了表征.     

Study on incident laser modulation using surface micro-defects on KH₂PO₄ crystal

KH2PO4 crystal is a crucial optical component of inertial confinement fusion.Modulation of an incident laser by surface micro-defects will induce the growth of surface damage,which largely restricts the enhancement of the laser induced damage threshold.The modulation of an incident laser by using different kinds of surface defects are simulated by employing the three-dimensional finite-difference time-domain method.The results indicate that after the modulation of surface defects,the light intensity distribution inside the crystal is badly distorted,with the light intensity enhanced symmetrically.The relations between modulation properties and defect geometries(e.g.,width,morphology,and depth of defects) are quite different for different defects.The modulation action is most obvious when the width of surface defects reaches 1.064 μm.For defects with smooth morphology,such as spherical pits,the degree of modulation is the smallest and the light intensity distribution seems relatively uniform.The degree of modulation increases rapidly with the increase of the depth of surface defects and becomes stable when the depth reaches a critical value.The critical depth is 1.064 μm for cuboid pits and radial cracks,while for ellipsoidal pits the value depends on both the width and the length of the defects.     

Effects of thiol-ene click reaction on morphology and electro-optical properties of polyhedral oligomeric silsesquioxane nanostructure-based polymer dispersed liquid crystal film

Polymer dispersed liquid crystals (PDLCs) have lit a flash of interest due to the distinctive property of electrically controlled switching. However, too high-driving voltage associated with porous polymer networks always limit their wider range of applications. Herein, we reported a PDLC system containing LCs, 2,2′-(Ethylenedioxy)diethanethiol (DET) with thiol groups, cage-like nanostructure acrylic polyhedral oligomeric silsesquioxane (KH570-POSS) and KH570-SiO₂ nanoparticle modified by acrylic groups. The cage-like KH570-POSS microstructure was injected to the polymer matrix when KH570-POSS reacted with DET via thiol-ene click reaction. The morphological results demonstrated that the droplet size increased with the higher content of DET due to the decrease of the crosslink between the acrylic groups in KH570-POSS, which results in a less dense of polymer network and thus make the LC droplets easier to be driven in the electric filed. Then, a silica-based nanoparticle KH570-SiO₂ modified by acrylic groups was introduced into the system. The results indicated that KH570-SiO₂ could replace partial KH570-POSS to form the polymer network via thiol-ene click reaction, which increased the compatible ability of SiO₂ nanoparticles in the as-made film. The contrast ratio was increased to 165 when there was nearly 5 wt% content of KH570-SiO₂. Besides, the driving voltage was reduced by almost 60% and the sample could be fully driven by 30 V which is lower than the safe voltage (36 V). This study opens a route for the preparation of commercial PDLC films by thiol-ene click reaction, enabling the creation of low-voltage-driven smart windows.