Rice Husk‐derived Hierarchical Micro/Mesoporous Carbon–Silica Nanocomposite as Superior Filler for Green Electronic Packaging Material

In this study, a carbon‐controllable hierarchical micro/mesoporous carbon–silica material derived from agricultural waste rice husk was easily synthesized and utilized as filler in an epoxy matrix for electronic packaging applications. Scanning electron microscopy, thermogravimetric analysis, and N₂ adsorption/desorption isotherms were used to characterize the morphology, thermal stability, carbon content, and porous structural properties, respectively, of the as‐obtained carbon–silica material, namely rice husk char (RHC ). As a filler material, the uniformly dispersed RHC filler in the epoxy/RHC composite was easily prepared through hydrogen bonding of the silanol group of silica with the epoxy matrix. For electronic packaging applications, the thermal conductivity and thermomechanical properties (storage modulus and coefficient of thermal expansion) of the epoxy/RHC composites improved with increasing carbon content. Moreover, loading of the 40% RHC filler substantially enhanced the storage modulus of the epoxy/RHC composite (5735 MPa ) compared to the epoxy with 40% commercial silica filler (3681 MPa ). Considerable commercial potential is expected for the carbon–silica composite because of the simple synthesis process and outstanding performance of the prepared packaging material.     

Enhanced Thermal Stability in SiO2/Carbon Filler Derived from Rice Husk via Microwave Treatment for Electronic Packaging Application

Here we report the effect of microwave treatment on a silica–carbon (SiO₂ /C) filler derived from rice husk and the function of the microwave‐treated filler in an epoxy matrix for electronic packaging applications. Thermogravimetric analysis revealed improved thermal stability of the SiO₂ /C filler upon microwave treatment. X‐ray diffraction analysis indicated partial SiC formation after the microwave treatment. For packaging applications, compared to that of the pure epoxy polymer, the thermal conductivity of the epoxy–SiO₂ /C composite was improved by 178% at 40 wt % content of the microwave‐treated SiO₂ /C filler. Furthermore, an improvement of 149% in storage modulus and 17.6°C in glass transition temperature of the epoxy–SiO₂ /C composites was realized. The improvement in thermal stability of SiO₂ /C filler could be achieved via a simple microwave treatment, which in turn enhanced the thermal stability, thermal conduction, and thermomechanical strength of the electronic packaging materials.     

高比表面积有序介孔氧化铝的制备与表征

采用溶胶-凝胶法以非离子表面活性剂PEO-PPO-PEO三嵌段共聚物F127为模板剂, 以异丙醇铝为铝源, 以异丙醇为溶剂, 成功地制备出比表面积为485 m2/g、孔径分布窄(2~20 nm)、孔容在1.2 cm3/g以上和孔道呈蠕虫状且具有一定有序性的介孔氧化铝. 采用BET, TEM, XRD和TG多种测试技术对产物性能进行了表征. 探讨了水铝比、醇水混合溶液的滴加速度、反应时间、水浴温度、陈化温度及陈化时间等条件对合成的有序介孔氧化铝结构的影响.     

介孔氧化铝的制备及应用

本文介绍了介孔氧化铝(MA)的各种制备方法,概括了MA制备的分析表征方法,如TEM、SAED、XRD、LAXRD、气体吸附-脱附、DT-TGA等。通过平均孔径、比表面积、MA形貌等因素,讨论和总结了制备方法、铝源、模板剂、反应物配比、pH值和后处理方法等对MA制备和热稳定性的影响,综述了近年来MA的研究和应用进展,并对今后的研究方向进行了展望。     

Preparation of Mesoporous Molecular Sieves AI-MSU-S Using Ionic Liquids as Template

Mesoporous molecular sieves A1-MSU-S has been prepared from the precursor of zeolite Y using ionic liquids1-hexadecane-3-methylimidazolium bromide(CMIMB)as a template in basic medium,which exhibited larger porediameter,pore volume and surface area than that synthesized using cetyl trimethyl ammonium bromide(CTAB)template.     

丙酮+环己烷+甲醇组成的最低共沸混合物热力学性质的研究

Mesoporous molecular sieves Al-MSU-S has been prepared from the precursor of zeolite Y using ionic liquids 1-hexadecane-3-methylimidazolium bromide （CMIMB） as a template in basic medium, which exhibited larger pore diameter, pore volume and surface area than that synthesized using cetyl trimethyl ammonium bromide （CTAB） template.     

介孔氧化铝的溶胶-凝胶法制备

以硝酸铝为铝源,十六烷基三甲基溴化铵和尿素为复合模板剂,采用溶胶-凝胶法制备了介孔氧化铝（1）,其结构经TEM, XRD, TG-DTA和N₂-BET表征。结果表明：1比表面积较大（＞400 m²·g^-1）,孔径分布窄(3～5 nm),形成的蠕虫状孔道具有短程有序性。     

制备不同孔径的氧化铝模板

将适量的有机溶剂加入电解液中，在15 ℃左右制备得到孔径大于200 nm的氧化铝模板.该法使电解时间缩短，加快了制备模板的过程， 是氧化铝模板的有效制备方法.将该方法与传统方法相结合，可以制备孔径在20～250 nm间的氧化铝模板. 实验表明：有机溶剂的加入可有效避免电解时热量的迅速产生, 通过改变实验条件可调控氧化铝模板的孔径.     

以凝聚子聚集体为模板制备TiO2纳米材料及其性质研究

合成了一种可用作凝聚子(Gelator)并带正电荷的胆固醇酯类化合物.研究其在溶剂中的聚集行为,并以其聚集体为模板,通过Sol-gel方法制备了一维TiO2纳米材料.改变凝聚子和TiO2前驱体的用量比,用扫描电镜观察到生成的TiO2纳米材料具有不同的尺寸和形貌,表明二者的比例对于体现模板转录功能的优劣具有重要意义.圆二色谱(CD)表明,形成的凝胶聚集体具有手性特征.XRD结果表明,生成的TiO2纳米材料具有锐钛矿晶型.通过光催化染料褪色实验,对所得TiO2纳米材料的光化学活性进行了初步研究.     

以花瓣为模板制备TiO2分层介孔纳米片

以月季花花瓣为模板, 经钛盐溶液浸渍后煅烧, 合成了新型TiO2 分层介孔纳米片. 采用X射线衍射(XRD)、 场发射扫描电子显微镜(FESEM)、 环境扫描电子显微镜(ESEM)、 透射电子显微镜(TEM)、 紫外-可见漫反射光谱(UV-Vis/DRS)和氮气吸附-脱附曲线分析等手段对样品进行了表征. 结果表明, 所得样品由厚度约4 nm的具有生物形态结构的锐钛矿型TiO2 纳米片组成. TiO2 薄层表面存在大量介孔, 其孔径集中分布于4 nm左右. 由紫外-可见漫反射吸收光谱可知, 材料的吸收边较纳米TiO2 (P25)红移了约20 nm, 因而具有更高的可见光光催化活性. TiO2 分层介孔纳米片在阳光下表现出较强的光催化活性, 在90 min内对亚甲基蓝的降解率可达98%, 远高于TiO2 纳米粉.     

阳极氧化铝模板合成介孔CeO2纳米纤维及其光致发光性能

以多孔阳极氧化铝膜(AAO)为模板,将模板的纳米孔洞作为微腔反应器,以聚环氧乙烯醚-聚环氧丙烯醚-聚环氧乙烯醚三嵌段共聚物(P123)为致孔剂、Ce(NO3)3.6H2O为铈源、无水乙醇为溶剂合成前躯体,采用压力诱导的方法将前躯体注入到AAO孔道内,经加热处理后,在模板的纳米孔洞内合成了具有介孔结构的一维CeO2纳米材料。通过SEM、TEM、XRD、EDS和N2吸附-脱附进行表征,结果表明,所合成的介孔CeO2纳米纤维具有介孔结构和较大的比表面积,并考察了其光致发光性能。     

孔性氧化铝模板与一维纳米新材料的制备

纳米材料尤其是以碳纳米管有序阵列为代表的一维纳米阵列材料的重要价值,促进了人们对模板合成方法的研究。本文简要回顾和总结了近年来有关孔性氧化铝模板的制备及其应用的研究进展,结合我们实验室的部分相关研究工作,揭示了孔性氧化铝模板在合成与组装一维纳米新材料方面的重要作用,以进一步活跃和促进该重要领域的研究和发展。     

Combinatorial Chemistry—Challenge and Chance for the Development of New Catalysts and Materials

One should not underestimate the capability of the combinatorial method in solid-state chemistry; this is the opinion of the author. Combinatorial chemistry can provide a large number of new compounds, but once the components that are interesting for a certain application have been successfully selected, the techniques of conventional catalysis and materials research are required. The strengths of conventional chemistry lie in the optimization, systematic modification, and improvement of new lead structures. In contrast, discovery is the potential strength of combinatorial chemistry. Careful design is most important for the synthesis of useful libraries, since the diversity of the periodic table is much too large to be accessed comprehensively or systematically by such large libraries.     

Preparation of a trihydrazinotriazine-functionalized core-shell nanocatalyst as an extremely efficient catalyst for the synthesis of benzoxanthenes

In recent years, there is a high demand on utilizing heterogeneous nanocatalysts in organic synthetic routes because of their green approach, facile purification of the products, and reusability of the catalyst. Herein, we introduced trihydrazinotriazine (THDT)-coated Fe₃O₄@SiO₂ as a novel amino-functionalized magnetic nanocompostie. We fully characterized the nanocatalyst and proved the morphology and magnetic property of the nanoparticles by using essential analyses. The basic attribute of the amino-rich porous surface of the nanocomposite provides a desirable environment for enhancing various reaction conditions. To examine the applicability of the nanocatalyst in organic reactions, we synthesized several benzoxanthenes using Fe₃O₄@SiO₂-THDT nanocatalysts. The nanocomposite successfully improved the reaction conditions and provided the benzoxanthenes in an environmentally friendly procedure, which afforded product in excellent yields (80–96%) and reduced time. The nanomagnetic catalyst was easily recovered after each trial by using an external magnet. After six successive runs, the loss of catalytic activity of the nanocomposite was negligible. Finally, we propounded a plausible mechanism for the preparation of the benzoxanthenes derivatives using the THDT-functionalized core-shell magnetic nanocatalyst.     

模板法制备介孔氧化铝及Eu3+离子组装

通过溶胶-凝胶法,以三嵌段共聚物F-127为模板制备有序介孔氧化铝(P-Al2O3)粉末,用热失重分析、X射线粉末衍射(XRD)、低角X射线粉末衍射(LAXRD)和比表面测量仪进行物相分析与孔径分析,利用高倍透射电子显微镜(HRTEM)表征介孔材料的形貌.研究表明,40℃下制备的介孔氧化铝经过高温除模板后,孔径大小分布较集中,有序性好.进一步通过水热反应法,获得了Eu3 的P-Al2O3组装体.研究了组装体系的光谱特性,并观察到介孔氧化铝基质与客体离子Eu3 之间产生的能量传递现象.     

纳米TiO2介孔薄膜的模板组装制备研究

以TiCl₄为无机前驱体、三嵌段高分子共聚物EO₂₀PO₇₀EO₂₀为模板剂，在非水条件下制备了有序的锐钛矿TiO₂纳米晶介孔薄膜。通过热重-差热（TG-DTA）分析、X射线衍射（XRD）分析、原子力显微观察（AFM）及N₂吸附-脱附等测试对样品进行了表征。结果表明，薄膜具有均一的大介孔孔径（～10 nm），其BET比表面积为150 m²·g^-1，薄膜较宽的无机壁厚显著提高了介孔结构的热稳定性。通过红外（IR）光谱分析考察了溶胶-凝胶过程中发生的物理化学变化。在对薄膜表面形貌进行AFM观察的基础上初步探讨了嵌段共聚物EO₂₀PO₇₀EO₂₀对薄膜孔结构形成的导向机理。     

Ionic liquids-assisted greener preparation of silver nanoparticles

1. Download : Download high-res image (298KB)
2. Download : Download full-size image

     

The Development of Bioglass Ceramics for Medical Applications

The enormous progress made in the field of medicine over the past few decades has been partly due to the introduction of new instruments but also a result of the use of new materials. It is impossible to imagine modern medicine without metals, alloys, sintered corundum, organic high polymers (also as composite materials), glassy carbon, etc. Bioglass ceramics open up new possibilities for medical treatment and constitute a new area of research in the natural sciences and medicine. Owing to their widely variable combinations of properties, bioglass ceramics can be more easily adapted to suit medical requirements than can customary implants. Two properties of bioglass ceramics are of primary importance: their biocompatibility, i.e., acceptance of the material by the tissues of the human body without irritation, rejection reactions, or toxic effects; and their bioactivity, i.e., the ability to establish firm intergrowths with tissues of the human body. This property is not shared by any of the classical biomaterials. A wide range of applications is envisaged for the bioglass ceramics that have so far been developed; some are still undergoing animal tests while others are being clinically tested in humans. Possible applications are the replacement of vertebrae and use in the middle ear, throat, nose, and eye, in the entire head region, in the shoulder and leg, and in dental prosthetics, in particular the replacement of dental roots (a hard tissue substitute in the broadest sense of the word). The question as to the behavior of a bone/bioglass ceramic contact or bond on a long-term scale and on being exposed to varying mechanical stress has still not been satisfactorily answered, because interdisciplinary research in this field is still immature. All observations made so far indicate, however, that the materials do not cause any adverse effects.     

Template Effects in SN2 Displacements for the Preparation of Pseudopeptidic Macrocycles

Macrocyclisation reactions of C₂‐symmetric pseudopeptides containing central pyridine‐derived spacers are affected by the presence of different anions. The selection of the proper anion gives excellent results for the preparation of the corresponding macrocyclic structures. Kinetic studies show that the presence of those anions enhances both the yield and the rate of the reaction. Computational studies at the B3LYP/6‐31G* level have allowed us to rationalise the experimental results. The obtained transition states (TSs) show that the interaction between the anion and the open‐chain pseudopeptidic chain has a stabilising effect. The anion stabilises the two TSs involved: the first one, which involves the formation of the initial bond between the two subunits and leads to an open‐chain intermediate, and the second one, which precedes the formation of the cyclic structure. The optimum anion (Br^? when the central spacer is derived from 2,6‐bis(aminomethyl)pyridine, is able to act as a template, in that it forces the two ends of the open‐chain intermediate to approach each other by forming hydrogen bonds with the two amino acid subunits present in the intermediate. This stabilises the second TS to a greater extent than the first one, and thus, favours macrocyclisation over the competing oligomerisation reactions. The computational calculations also allowed us to predict the outcome of new experiments. Accordingly, the synthesis of the pseudopeptidic macrocycle derived from 2,6‐diaminopyridine was not successful under the optimised conditions previously used. Nevertheless, calculations predicted that in this case Cl^? should be more efficient than Br^?, and this was subsequently experimentally confirmed. Interestingly, the presence of different substituents on the constituent amino acids seems to play a minor role in the overall process.     

负载Ni金属有序介孔氧化铝催化剂的制备及表征

采用原位合成法和传统浸渍法以价格低廉的硝酸铝作为铝源, 聚乙二醇1540为模板剂, 硝酸镍为镍源, 制备出负载Ni金属有序介孔氧化铝催化剂, 并采用BET、TEM、XRD、TG多种测试技术对合成催化剂的物理化学性质和结构特征进行了表征. 实验结果表明, 两种方法均能制备出比表面积大(＞210 m2·g-1)、孔径分布窄(4 nm左右)的负载Ni金属介孔氧化铝催化剂. 与浸渍法相比, 原位合成法所制备的负载Ni金属有序介孔氧化铝镍离子与载体具有更强的相互作用力, 且孔结构具有一定的有序性.