Precise Synthesis and Thin Film Self-Assembly of PLLA-b-PS Bottlebrush Block Copolymers

The ability of bottlebrush block copolymers (BBCPs) to self-assemble into ordered large periodic structures could greatly expand the scope of photonic and membrane technologies. In this paper, we describe a two-step synthesis of poly(l-lactide)-b-polystyrene (PLLA-b-PS) BBCPs and their rapid thin-film self-assembly. PLLA chains were grown from exo-5-norbornene-2-methanol via ring-opening polymerization (ROP) of l-lactide to produce norbornene-terminated PLLA. Norbonene-terminated PS was prepared using anionic polymerization followed by a termination reaction with exo-5-norbornene-2-carbonyl chloride. PLLA-b-PS BBCPs were prepared from these two norbornenyl macromonomers by a one-pot sequential ring opening metathesis polymerization (ROMP). PLLA-b-PS BBCPs thin-films exhibited cylindrical and lamellar morphologies depending on the relative block volume fractions, with domain sizes of 46–58 nm and periodicities of 70–102 nm. Additionally, nanoporous templates were produced by the selective etching of PLLA blocks from ordered structures. The findings described in this work provide further insight into the controlled synthesis of BBCPs leading to various possible morphologies for applications requiring large periodicities. Moreover, the rapid thin film patterning strategy demonstrated (>5 min) highlights the advantages of using PLLA-b-PS BBCP materials beyond their linear BCP analogues in terms of both dimensions achievable and reduced processing time.     

Strain effects on multiferroic BiFeO3 films

The field of multiferroics has experienced a rapid progress resulting in the discovery of many new physical phenomena. BiFeO₃ (BFO) compound, which is one of the few room-temperature single-phase multiferroics, has contributed subsequently to this progress. As a result, significant review articles have been devoted specifically to this famous system. This chapter is dedicated to the strain effects on the structure stability and property changes of BFO thin films. It is a short and non-exhaustive topical overview that may be seen as an invitation for interested readers to go beyond. There is a very active and prolific research in this field and we apologize to the authors whose relevant work is not cited here. After a short introduction, we will thus review the effect of strain on BFO films by describing the consequences on the structure and the phase transitions as well as on polar, magnetic and magnetoelectric properties.     

基于DIS数字信息化系统对透光物质透光性能的研究

采用DIS数字信息化系统,对不同浓度的蓝墨水溶液在激光光源照射下的透射平均照度及照度分布图像进行实验研究,得到了平均照度值随溶液浓度变化的规律。对不同颜色塑料膜片对白炽灯光源透过照度值及照度分布图像进行实验研究得到及其相关之规律。     

Activation of peroxyl and molecular oxygen using bis -benzimidazole diamide copper (II) compounds

New tetradentatebis-benzimidazole ligands have been synthesized and utilized to prepare copper (II) complexes. Some of these copper (II) complexes have been characterized structurally. The copper (II) in these complexes is found to possess varying geometries. A distorted octahedral geometry is found with a highly unsymmetrical bidentate nitrate group. An unusual polymeric one-dimensional structure is observed where copper (II) is in a distorted square pyramidal geometry with a monodentate nitrate ion, having long Cu-O bond, while a distorted triagonal bipyramidal geometry is found with two carbonyl O atoms and a Cl atom in the equatorial plane, and two benzimidazole imine N atoms occupy the axial position. These compounds are found to activate the cumylperoxyl group, and this has been utilized in the facile oxidation of aromatic alcohols to aldehydes, where they act as catalysts with large turnovers. The yields of the respective products vary from 32 to 65%. The role of molecular oxygen has been studied and an attempt has been made to identify the “active copper species”. Activation of molecular oxygen has also been observed and has been used for oxidative dealkylation of a hindered phenol, producing di-butyl quinones with yields of 20–25% and 10–12 fold catalytic turnover. Dihydroxybenzenes and substituted catechols are also readily oxidized to the corresponding quinones, in oxygen-saturated solvents. Yields of 84% have been observed with 34-fold catalyst turnover, with di-t-butylcatechol. The activity of these copper (II) —bis-benzmidazolediamide compounds is reminiscent of the functioning of copper centres in galactose oxidase, tyrosinase and catechol oxidase.     

Systematic investigations of the multi-element preconcentration from copper by precipitation of the matrix as copper(I) oxide and copper(I) thiocyanate

Two methods for multi-element preconcentration from copper by reductive matrix precipitation are presented. In systematic investigations on the coprecipitation behaviour of Ag, Al, Au, Bi, Cd, Co, Cr, Fe, Ga, In, Mn, Mo, NJ, Pb, Sb, Se, Sn, Te and Zn during precipitation of the copper matrix as Cu₂O or CuSCN, the separation parameters were optimized. By combination with a hexamethyleneammonium hexamethylenedithiocarbamate collector precipitation, a concentration of 8 elements (Cu₂O precipitation) or 13 elements (CuSCN precipitation) in a small volume was achieved. The limits of detection of the procedures are, depending on the element, 0.1–5 μg g^?1 for flame atomic absorption spectrometry (AAS) and 0.01–0.1 μg g^?1 for graphite furnace AAS. The relative standard deviations are about 3%. The analytical performance of the procedures is compared with that of an electrolytic copper separation.     

Au-Au2S复合纳米球壳微粒的空腔谐振及参量讨论

Au-Au2S复合纳米球壳微粒（金纳米球壳），是一种新型复合结构的纳米微粒，其结构为纳米级的Au2S介质球外包裹了一层几个纳米厚的黄金球壳。这种复合纳米球壳微粒可以被抽象为球型谐振腔。报道了它的空腔谐振吸收的实验结果，并且运用经典理论结合介观结构特征，讨论了有关Au-Au2S复合纳米球壳微粒空腔谐振吸收的一些重要参量，其中包括谐振吸收波长、品质因数、谐振能量等。另外，还讨论了金球壳的厚度对这些重要参量的影响。     

Laser induced copper electroless plating on polyimide with Q-switch Nd:YAG laser

The results of laser induced deposition of copper on polyimide substrate from copper electrolyte solution are reported. Unlike most work reported in the literatures where CW Ar⁺ lasers were used, a second harmonic (532 nm wavelength) Q-switch Nd:YAG laser was used for our experiments. The deposition process was conducted by laser-catalyzing of the polyimide surface and subsequent photothermal-accelerated reduction of copper-complex ions in an alkaline reducing environment. The characteristics of the deposited copper line were investigated in terms of laser beam scanning speed, and the number of scans. The surface morphology and chemical composition of the deposited copper were analyzed using field emission scanning electron microscope (FESEM) and energy dispersive spectrometer (EDX). The optimum processing conditions have been identified. The copper deposit was found to adhere well to the substrate.     

Conjugate addition of pyrroles to α,β-unsaturated ketones using copper bromide as a catalyst

Copper bromide was used as a catalyst for the addition of pyrroles to enones. When both the reactants were used in equimolar amounts, mono and dialkylated products were obtained. However, the use of excess enone furnished only dialkylated products. Thus, copper bromide was shown to be an efficient catalyst for the dialkylation of pyrroles.     

蓝宝石R面上ZnO薄膜的NH3掺杂研究

以NH₃为掺杂源,利用金属有机化学气相沉积(MOCVD)系统在蓝宝石R面上生长出掺氮ZnO薄膜。通过XRD,SEM测量优化了其生长参数,在610℃和在80sccm的NH₃流量下生长出了〈1120〉单一取向的ZnO薄膜。经Hall电阻率测量,得知该薄膜呈现弱p型或高电阻率,并对其光电子能谱进行了研究。     

Diffusion Structural Analysis Study of Titania Films Deposited by Sol-Gel Technique on Silica Glass

The diffusion structural analysis (DSA) was used to characterize microstructure changes of hydrous titania gel films under in situ conditions of heating. TG and DTA were used in order to elucidate the processes controlling the formation of anatase film during heating of hydrous titania gel film. The annealing of porosity and near surface structure defects of the dehydrated titania films was indicated by DSA in the temperature range 255–700°C as the decrease of radon release rate. It was demonstrated that the annealing was enhanced on heating in oxygen in comparison with heating in argon. The DSA experimental results were compared with model curves describing the radon diffusion mobility and the annealing of radon diffusion paths.