Hierarchical Mesoporous Silica Fabricated from an ABC Triblock Terpolymer as a Single Template

Hierarchical mesoporous silicas containing two kinds of mesoporous size are successfully synthesized using the simple evaporation‐induced self‐assembly (EISA) strategy. Two blocks of hydrophobic segments (PE and PCL) in the poly(ethylene‐block‐ethylene oxide‐block‐ϵ‐caprolactone) (PE‐PEO‐PCL) triblock copolymer are involved in the two types of mesopore after calcination, the PE segment being attributed to the face‐centered cubic (fcc) morphology (spherical pores) and the PCL segment attributed to the tetragonal cylinder structure (cylindrical pores).     

Concentric Circular Approach in Mesoporous Silica Transition Process from Hexagonal to Vesicular Structure

We studied the synthesis of mesoporous silica from cetyltrimethyl ammonium bromide(CTAB) and sodium dodecyl sulfate(SDS) at different molar ratios(R). X-ray diffraction(XRD), scanning electron spectroscopy (SEM), transmission electron spectroscopy(TEM) and nitrogen sorption analysis were then used to further investigate the internal relationship among different morphologies and structures, as well as the mechanism of the transition from hexagonal to vesicular structure. The results reveal that as R increased, a consistent and gradual transition occurred via a concentric circular secondary structure formed. The antagonistic effect between the decreasing curvature of surfactant micelle and increasing curvature of secondary structures may be the reason for the complex morphologies synthesized, and the increasing bending energy ΔG_b is the main driving force for the transition.     

两亲性三嵌段共聚物PAA-PHB-PAA的合成及表征

本文用ATRP方法, 以两端溴化的聚β-羟基丁酸酯链段(Br-PHB-Br)作为大分子引发剂, 丙烯酸叔丁酯为单体, 合成了一种新的三嵌段共聚物聚丙烯酸叔丁酯-聚β-羟基丁酸酯-聚丙烯酸叔丁酯(PtBA-PHB-PtBA). 在酸性条件下进一步水解, 得到了一种两亲性的聚丙烯酸-聚β-羟基丁酸酯-聚丙烯酸(PAA-PHB-PAA)三嵌段共聚物.     

溶剂尺寸对ABA两亲性三嵌段共聚物在选择性溶剂中自组装行为影响的Monte Carlo模拟

采用Monte Carlo模拟方法研究了溶剂尺寸对ABA两亲性三嵌段共聚物在选择性溶剂中自组装行为的影响。模拟结果表明,溶剂尺寸是决定共聚物聚集形态的重要因素之一。随着溶剂尺寸的增大,嵌段共聚物自组装所形成的胶束可以发生从球状到棒状再到囊泡状的转变。通过对各组分的相互作用对数随溶剂尺寸变化曲线的分析发现,增大溶剂尺寸会使溶剂的溶解性变差,由此引发体系中的一系列形态转变。此外,通过对体系自组装形貌结构相图的分析发现,增大溶剂尺寸或增加疏水作用同减小亲水作用对于自组装形态的改变具有同等效果。     

以新型模板方法合成中孔SiO2分子筛

以廉价、生物可降解的两性表面活性剂十四烷基甜菜碱作为模板剂,以正硅酸乙酯为 硅源,在酸性条件下成功地合成了具有螺旋状孔道结构的SiO2中孔分子筛.热重表征结果说 明,采用溶剂萃取（乙醇的水溶液为萃取剂）的方法,近乎100％的模板剂可以脱除回收.     

二元阴阳离子表面活性剂法合成介孔氧化硅囊泡

以十二烷基磺酸钠(SDS)和十六烷基三甲基溴化铵(CTAB)为表面活性剂, 在SDS与CTAB的摩尔比为1.0~2.3时, 以正硅酸乙酯(TEOS)为硅源, 在氨水-水体系中于68℃下合成介孔氧化硅囊泡. 通过透射电子显微镜(TEM)、 X射线衍射仪(XRD)、 热重分析仪(TGA)和氮气吸附-脱附实验仪对合成的产物进行表征. 结果表明, 合成的产物为介孔氧化硅囊泡聚集体, 孔径约为4 nm, 样品的Brunauer-Emmett-Teller(BET)比表面积为826 m²/g. 对介孔氧化硅囊泡的形成机理做了初步探讨.     

混合表面活性剂模板法合成立方相介孔含钛氧化硅

自1992年Ｍｏｂｉｌ公司的Ｍ41Ｓ系列介孔氧化硅分子筛问世以来[1,2],借助表面活性剂液晶模板方法合成各种孔结构与不同大小孔径的硅基分子筛材料引起了人们的极大兴趣,目前多数工作仍然集中于六方相的介孔分子筛.具有双连续的三维交织立方排列孔道结构的ＭＣＭ48由于其孔道不易堵塞和良好的骨架结构稳定性[3,4],在催化、吸附和与其为载体的制备等方面具有独特的应用价值.但由于液晶模板形成立方相区的范围非常狭窄,相应的分子堆积比对模板剂分子几何结构要求较苛刻,采用单一表面活性剂为模板剂合成时,条件难以掌握,制备ＭＣＭ48十分困难.Ｈ…     

Synthesis and Self-assembly of a Linear Coil-Coil-Rod ABC Triblock Copolymer

An interesting order-order transition between two different complex nanostructures was observed in a new liquid crystalline linear coil-coil-rod ABC triblock copolymer（tri BCP）. First, the ABC tri BCP, poly（dimethylsiloxane）-bpolystyrene-b-poly{2,5-bis[（4-methoxyphenyl）oxycarbonyl]styrene}（PDMS-b-PS-b-PMPCS）, was synthesized through sequential atom transfer radical polymerization. The degrees of polymerization of PDMS, PS, and PMPCS blocks are 58, 159, and 106, and the corresponding volume fractions of PDMS, PS, and PMPCS are 0.09, 0.29, and 0.62, respectively. The phase behaviors of the PDMS-b-PS diblock copolymer precursor and the final triblock copolymer were studied by smallangle X-ray scattering, one-dimensional wide-angle X-ray scattering, and transmission electron microscopy experiments. The PDMS-b-PS precursor self-assembles into hexagonally packed cylinders with a relatively small periodic size after thermal annealing. When the triblock copolymer is annealed at a relatively low temperature（120 ○C） at which the PMPCS block is in the amorphous state, the tri BCP forms core-shell hexagonally packed cylinders（CSH） with a relativly large periodic size. After the tri BCP is annealed above 140 ○C at which the PMPCS block transforms to the liquid crystalline（LC） phase, the nanophase-separated structure transforms to a three-phase four-layer lamellar structure（LAM-3P4L）. Thus, accompanied with the transition of the PMPCS blocks from the amorphous state to the LC phase, the order-order transition from CSH to LAM-3P4 L occurs in the PDMS-b-PS-b-PMPCS ABC tri BCP.     

Synthesis of Mesoporous Carbon Monolith by Direct Carbonization of Compressed Sucrose/Silica Composite

Mesoporous carbon monolith was synthesized by the direct carbonization of compressed sucrose/silica composite,which was prepared by using sol-gel method. The structural and textural properties of the materials were investigated by XRD,DRIFT,N2-adsorption and SEM. The characterization study shows that the resultant carbon monolith possesses a relatively high surface area,large pore volume and well interconnected pore system. Addition of a certain amount of citric acid or aluminum nitrate into the sol-gel pre...     

Synthesis of Amphiphilic ABC Triblock Copolymers with PEO as the Middle Block

Summary: Stepwise anionic polymerization, catalytic hydrogenation, and atom transfer radical polymerization were performed to synthesize an amphiphilic ABC triblock copolymer, poly(ethylene‐alt‐propylene)‐block‐poly(ethylene oxide)‐block‐poly(hexyl methacrylate) (PEP‐b‐PEO‐b‐PHMA), with hydrophilic PEO as the middle block. The resulting block copolymers have well‐defined molecular weights and narrow molecular weight distributions as revealed by ¹H NMR spectroscopy and gel permeation chromatography.

GPC chromatograms of an ABC triblock copolymer, PEP‐b‐PEO‐b‐PHMA, and its intermediate precursors exhibiting narrow polydispersities.     

Synthesis of Mesoporous Silica Molecular Sieves via a NovelTemplating Scheme

ThediscoveryofM41SfamilyofmesoporousmolecularsievesbyMobilresearchersI'2hasstimulatedconsiderableinterestintheuseofthesematerialsascatalysts,catalystsupports,aswellasadsorbents3'#.Intheoriginalreport"=,MCM-41waspreparedfromaself-assemblyprocesswhichinvolveselectrostaticinteractionsbetweenpositivelychargedquaternaryammoniummicelles(S )andinorganicanions(l-)usedasframeworkprecursors.Huoetal5extendedtheelectrostaticassemblyapproachesbyproposingfourcomplementarysynthesisschemes(S l-,S-I ,S X-…     

Synthesis and Characterization of Mesoporous Silica Templated by Amphiphilic RTILs

This article reports a novel preparation of mesoporous silica with series of 1-alky-3-methylimidazolium bromide (C_nMIM)Br (n = 12, 14, 16), a kind of amphiphilic room-temperature ionic liquids (RTILs), as a template via a sol-gel nanocasting technique. The pore morphology and structures of these mesoporous silica were characterized by Transmission electron microscopy (TEM). The results show that the RTIL bearing longer alkyl chain is preferred to form the mesoporous silica material with bigger pores. (C₁₆MIM)Br has been chosen to study how the various influencing factors affect the synthesis and structure of the mesoporous silica material, such as the acid concentration, the solling time, the gelling time and the calcination time. N₂ adsorption-desorption isotherms measurement was used to characterize the pore size distribution and BET surface area. The results indicate that all of the factors can make an influence on the preparation of the mesoporous silica, which is more sensitive to the concentration of the acid.     

"面包圈"状高有序度大孔径介孔分子筛SBA-15的合成

介孔材料因其高度有序的大孔径、较佳的催化吸附性能、良好的电磁性质及易于剪裁而引起人们极大的兴趣[1～9].人们已相继合成了介孔氧化硅薄膜[3,10]、球[12]、空心球[4,13]和纤维[12～15]等,并设法控制中孔材料晶体外貌[3～9,15～21].最近,我们报道了利用多相组装和无机晶体(如NaCl,LiCl)作大孔结构导向剂的方法[16],合成了人造"珊瑚"状介-大孔氧化硅膜[13].Lin等[17]用共表面活性剂法在丁醇存在下合成了多组有序结构的介孔氧化硅空心球; Shio等[21]在完全溶解的硅酸钠和阳离子表面活性剂溶液中,合成了细棒状介孔氧化硅粉末.本文报道一种控制介孔材料颗粒外貌和形状的新方法,即共溶剂法,并以此法合成了高有序度、大孔径、 "面包圈"状介孔氧化硅SBA-15.这种新材料有望在微加工、催化、生物分离、电子器件的矿化、色谱载体等方面得到应用[1～9].     

模板技术制备单块介孔分子筛

模板技术与溶胶 -凝胶过程结合是合成介孔分子筛的有效方法 .模板通常采用表面活性剂在一定条件下自组装形成超分子结构 ,在不同条件下 ,此超分子结构具有不同聚集形态 ,合成出的介孔分子筛也具有不同的孔道排列方式 [1～ 4 ] .溶胶 -凝胶过程是通过硅源体的水解缩合并缓慢蒸发除去溶剂实现的 .此过程及产物受体系的 p H值影响很大 .在碱性体系中制备的介孔材料通常为粉末状 ,不利于实际应用 ,因此人们更加重视合成具有规则外形的介孔材料[5] .目前报道大多是在酸性体系中制备不同形状的介孔材料 [6～ 12 ] .有关合成单块介孔分子筛的报道…     

Morphologies of Core-Shell-Cylinder-Forming ABC Star Triblock Copolymers in Nanopores

The self-assembly behavior of ABC star triblock copolymers can lead to a large number of nanostructures. Indeed, many new and interesting structures have already been discovered and proven to be hotspot in soft matter physics research. In this work, we introduce different phase diagrams of core-shell-cylinder-forming ABC star triblock copolymers under different conditions, including in-bulk and pore geometries with different sizes. The relation between the pore size geometries and their corresponding structures are also revealed. The different properties of the surface potential field that significantly affect the self-assembly process of ABC star triblock copolymers are investigated as well.     

介孔硅层柱蒙脱石材料合成的新方法与表征

利用十六烷基三甲基溴化铵(CTAB)将天然钠基蒙脱石改性成有机蒙脱石,以十二烷胺为模板剂,正硅酸乙酯为层柱前驱体,在室温下合成了新型介孔硅层柱蒙脱石材料.用XRD,TG,FTIR以及N₂等温吸附-脱附等技术对产物进行了表征.结果表明,合成材料具有大通道(净层间距为2.75nm)、介孔孔径且孔分布窄(平均孔径为2.17nm)、比表面积高(SBET=821.6m²/g)、热稳定性高(大于800℃)等特征.同时,通过改变中性胺的链长,研究了孔结构的调变规律,分析了材料的成孔机理和热稳定性提高的原因.     

孔壁部分有序化的介孔二氧化硅材料的合成与表征

采用一种“改进的二次晶化”的方法处理介孔二氧化硅SBA-15. 用X射线衍射(XRD)、 透射电镜(TEM)、 电子衍射(ED)、 红外光谱(FTIR)以及固体核磁共振(NMR)等多种技术对样品进行了表征.　结果表明， 在所得样品的孔壁中, 原子的排列方式与普通介孔二氧化硅材料的孔壁不同， 显示一定程度的有序性. 同时, 高度有序的介孔结构得到很好的保持, 且样品的水热稳定性大幅度提高.     

模板剂对全硅MCM-41介孔分子筛结构的影响

分别采用十六烷基三甲基溴化铵和十六烷基三乙基溴化铵作为模板剂,硅溶胶为硅源,用水热晶化法在碱性（NaOH）介质中合成了MCM-41介孔分子筛样品.通过XRD、N2吸附-脱附、TG-DTA、IR等测试手段对这两种样品进行了对比表征分析.考察了两种不同模板剂对其晶体结构、比表面及孔径大小的影响.实验结果表明,相对于十六烷基三甲基溴化铵做模板剂,采用大头基的十六烷基三乙基溴化铵可以合成较大孔径和孔容（分别为4.72 nm和1.14 cm3•g-1）的MCM-41介孔分子筛,而且具有较窄的孔径分布,因此对于合成大孔径的介孔分子筛MCM-41,十六烷基三乙基溴化铵是一种很好的模板剂.     

两亲聚合物胶束自组装包药研究进展

两亲聚合物胶束具有突出的理化性能和独特功能,能够在溶液中自组形成具有核壳结构的聚合物胶束,同时实现药物的负载。自组装包药技术能够缓解我国药物辅料缺乏的现状,符合目前药物辅料发展的新趋势。通过自组装形成的聚合物胶束在药物控释、药物靶向载体、药物制剂开发、新型药物辅料等方面具有广阔的应用前景。本文综述了两亲聚合物胶束自组装包载药物的原理以及方法,重点介绍了三类两亲聚合物在自组装包药方面的最新研究成果和发展趋势。本文还对载药胶束在药物释放方面的应用进行了概述。     

酸诱导介观相转变硅基介孔材料的合成机理及其改性

采用两步法以三嵌段共聚物P104(PEO27-PPO61-PEO27)为模板剂合成介孔材料, 研究了介孔材料结构随体系pH 值的变化, 探讨了体系中介观相转变的机理. 研究表明,随着pH 的升高, 发现体系中无机物种和模板剂所组成的介观相发生了转变,由P6mm 的SBA-15(pH=1.51-2.67)2D六角孔道结构转变为3D 蠕虫状孔道的MSU-X(pH=3.93-4.56)结构. 对所得的两种不同种类的硅基材料以γ-胺丙基三乙氧基硅烷(APTES: NH2(CH2)3Si(C2H5O)3)进行表面烷基化改性结果表明, 在同样的条件下, 经过改性后MSU-X类介孔材料孔壁上接枝的烷基数目要远超过SBA-15 类介孔材料.