Structure and plasmonic properties of thin PMMA layers with ion‐synthesized Ag nanoparticles

Silver nanoparticles are synthesized in polymethylmethacrylate by 30 keV Ag⁺ ion implantation with high fluences. The implantation is accompanied by structural and compositional evolution of the polymer as well as sputtering. The latter causes towering of the shallow nucleated Ag nanoparticles above the surface. The synthesized nanoparticles can be split into two groups: (i) located at the surface and (ii) fully embedded in the shallow layer. These two groups provide corresponding spectral bands related to localized surface plasmon resonance. The bands demonstrate considerable intensity making the synthesized composites promising for plasmonic applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 664–672     

Elimination of oxidation and decomposition by SnCl2 in the SERS study of pyridoxine on a roughened Au electrode

Severe interference from the oxidation and laser carbonization was encountered in the measurements of surface‐enhanced Raman scattering (SERS) spectra of pyridoxine (PN) on the roughened gold electrode. However, we found that high‐quality SERS spectra of PN could be obtained by the introduction of SnCl₂, which only has few Raman peaks at low wavenumbers. SnCl₂, as a good reductive, is capable of removing the oxidative species on the gold substrate and the dissolved oxygen in solution, and as a result lowering the open circuit potential (OCP). Sn(II) can also strongly chemically adsorb on the gold surface and interact with PN through coordination/chelation, such that not only to prevent PN from damage by the giant electromagnetic field for the ‘first‐layer’ effect, but also to give rise to very strong Raman scattering signals of PN where chemical enhancement plays an important role. Those are the main reasons for the elimination of the oxidation and decomposition of PN and for the high‐quality SERS spectra of PN. The way the SnCl₂ confines PN within the enhanced electromagnetic field by its ability of adsorption and coordination/chelation can be utilized to improve the routine SERS analysis of analogous type of reactive organic/biomolecules. In addition, this method has been successfully extended to the SERS measurements of PN on the substrates of roughened silver and copper. Copyright © 2008 John Wiley & Sons, Ltd.     

High-Flux Carbon Molecular Sieve Membranes for Gas Separation

Carbon membranes have great potential for highly selective and cost-efficient gas separation. Carbon is chemically stable and it is relative cheap. The controlled carbonization of a polymer coating on a porous ceramic support provides a 3D carbon material with molecular sieving permeation performance. The carbonization of the polymer blend gives turbostratic carbon domains of randomly stacked together sp² hybridized carbon sheets as well as sp³ hybridized amorphous carbon. In the evaluation of the carbon molecular sieve membrane, hydrogen could be separated from propane with a selectivity of 10 000 with a hydrogen permeance of 5 m³(STP)/(m²hbar). Furthermore, by a post-synthesis oxidative treatment, the permeation fluxes are increased by widening the pores, and the molecular sieve carbon membrane is transformed from a molecular sieve carbon into a selective surface flow carbon membrane with adsorption controlled performance and becomes selective for carbon dioxide.     

炭化温度对红柳林煤温和液化-炭化耦合转化产物的影响

在炭化温度为430-600℃研究了红柳林煤温和液化-炭化耦合转化过程的产物分布及理化性质。结果表明,半焦产率达40.64%-53.02%,有机液相产率达30.89%-36.98%,正己烷可溶物产率达29.74%-33.28%;在较低温度下炭化温度升高有利于正己烷可溶物产率提高,而在较高炭化温度下则相反;430℃炭化温度下半焦表现出较强黏结性,550℃炭化温度下半焦的黏结性消失,挥发分降至10%左右。通过调节炭化温度可使半焦定向用于配煤炼焦或无烟煤原料。     

辐照和碳化对SiC空心微球的影响

以聚碳硅烷（PCS）为原料,通过炉内成球技术制备SiC空心陶瓷微球,讨论辐照交联和高温碳化对SiC陶瓷微球化学成分、成键结构和表面特性的影响。结果表明,PCS在热处理过程中的失重率约为35%,其分解温度在400～800 ℃之间。微球经电子束辐照后会生成以SiCSi和SiOSi骨架结构为主的三维网络交联结构。碳化过程使SiCH3键,SiH键和CH键断裂,生成以SiC为主的无定形态SiC。辐照的均化作用使高温热处理碳化的微球能够维持完好的球壳结构,且具有更好的表面粗糙度和平整性。     

Palladated cyclodextrin and halloysite containing polymer and its carbonized form as efficient hydrogenation catalysts

β‐Cyclodextrin (β‐CD) and glycidyl methacrylate monomer were polymerized in the presence of functionalized halloysite nanoclay (Hal) to afford a polymeric network (Hal‐P‐CD) containing Hal and CD. Hal‐P‐CD was then applied as a catalyst support for the immobilization of Pd nanoparticles. The resulting nanocomposite, Pd@Hal‐P‐CD, could serve as a catalyst for the hydrogenation of nitrobenzene. The precise study by the preparation of control samples confirmed the contribution of CD as both phase transfer and capping agent, P (polymer) and Hal to the catalysis. Moreover, the results confirmed the importance of CD: glycidyl methacrylate monomer ratio. Pd@Hal‐P‐CD was also carbonized to prepare Pd@Hal‐C. Notably, the characterization of Pd@Hal‐C showed that carbonization led to the growth of mean diameter of Pd nanoparticles, increase of Pd content and partial destruction of Hal. However, the catalytic activity of Pd@Hal‐C was superior to Pd@Hal‐P‐CD. Pd@Hal‐C was also highly recyclable and could be recovered and recycled for several reaction runs. The study of the carbonization temperature showed that this factor affected the nature of the resulting carbon and the catalyst prepared at elevated temperature showed higher catalytic activity.     

聚丙烯腈基碳纤维的组织结构演变过程研究

用丙烯腈（AN）、衣糠酸（IA）、丙烯酸甲酯（MA）进行三元自由基溶液共聚合，经湿法纺丝制得聚丙烯腈（PAN）原丝，然后进行预氧化和碳化处理，并用SEM和TEM等分析方法跟踪过程中纤维微观结构的变化。结果表明：碳纤维的微观组织结构与原丝的微观组织结构密切相关，高强度、高取向度、结构均匀和弥散性好的原丝是获得高强度和高模量碳纤维的前提。     

富钙生物油煅烧过程中孔结构变化特性的研究

在热重分析仪上进行富钙生物油煅烧实验。结果表明,富钙生物油的煅烧过程分为三个阶段,分别是生物油部分组分的脱CO₂和H₂O阶段、有机酸钙盐分解阶段、碳酸钙分解阶段。其中,有机酸钙盐分解对煅烧产物的孔结构有重要影响。在450℃~600℃,气体析出的气蚀作用与生物油中高分子化合物的碳化沉积现象同时存在,两者共同作用,但后者占主导,高分子化合物的碳化沉积主要发生在500℃~600℃。600℃以后,碳酸钙开始分解,释放出CO₂,气蚀作用使煅烧产物内部形成新的微孔,产物具有发达的孔结构。相同煅烧温度下,富钙生物油煅烧产物的孔隙特性明显优于CaCO₃。     

稀土萃取分离废水制备高纯碳酸氢镁溶液过程中铁杂质的行为与影响

以稀土冶炼分离过程中产生的氯化镁废水和白云石为原料制备氢氧化镁,然后采用碳化法制备高纯碳酸氢镁溶液,研究了铁杂质离子的行为与影响。结果表明:碳酸氢镁溶液中的杂质铁是由于二价固态铁发生碳化反应而引入并以重碳酸亚铁(Fe(HCO3)2)形式存在,即碳化反应过程是除铁的核心工序,Mg(HCO3)2溶液经过除铁后沉淀稀土离子可以明显降低沉淀产物中铁杂质含量。本文为氯化镁废水-白云石碳化法制备碳酸氢镁溶液过程中铁杂质离子的去除提供切实可行的理论指导。     

四氯化碳与二甲基亚砜制备新型碳材料

报道了在固体KOH及相转移催化剂作用下 ,四氯化碳与二甲基亚砜 (DMSO)发生一种新颖碳化反应 ,生成棕色的富碳材料 .该富碳材料在 70 0℃下加热分解 ,提纯后得到直径为 30～ 80nm的多孔碳粒子 .该碳材料比表面积为 4 30m2 ·g-1,平均孔径为 2 .6× 10 -9m ,其结构中同时含有sp2 与sp3 杂化的碳原子