原位诱导生长法制备单分散M型钡铁氧体亚微空心球

提出了一种制备单分散M型钡铁氧体空心球的新方法,即以碳酸胍表面改性的单分散聚(苯乙烯-共-丙烯酸)P(St-co-AA)乳胶粒子为模板,在其表面原位诱导钡铁氧体前驱物的定位并生长,以此获得壳层均匀致密的P(St-co-AA)/钡铁氧体前驱物核壳复合粒子,再经过热处理得到结构完整、成分单一的M型钡铁氧体空心球.     

热解-还原法制备单分散Fe3O4亚微空心球

在用模板法水解FeCl3制备单分散聚(苯乙烯-共-丙烯酸)/Fe2O3[P(St-co-AA)/Fe2O3]核壳粒子的基础上, 于N2环境下热解内核直接得到了单分散的磁性Fe3O4亚微空心球. 用透射电镜(TEM)、场发射扫描电镜(FESEM)、X射线衍射(XRD)、振动样品磁强计(VSM)表征并测试了空心微球的结构形貌、成分以及静磁性能. 结果表明, P(St-co-AA)/Fe2O3核壳粒子在热处理过程中, 由于内核热解生成的有机小分子将Fe2O3 壳层同时还原为Fe3O4, 从而生成了粒径和壁厚均匀的单分散Fe3O4亚微空心球. 该空心微球在室温下的饱和磁化强度、剩余磁化强度和矫顽力分别为50.91 A·m2·kg-1、3.97 A·m2·kg-1和2.33 kA·m-1.     

单分散SnO2中空微纳米球的制备和性质

模板法是制备无机中空微纳米球的重要方法之一. 本文以苯乙烯为单体, 通过乳液聚合得到粒径约为620 nm的单分散聚苯乙烯(PS)微球. 以磺化后的聚苯乙烯(PSS)微球为模板, 利用阴阳离子静电吸附作用, 将PSS与前驱体SnSO₄中的Sn²⁺结合. 通过Sn²⁺在乙醇-水介质中的水解作用得到核-壳复合结构, 再经高温煅烧, 得到SnO₂中空微纳米球. 实验对前驱体的浓度、表面活性剂的用量、反应时间及模板选择等方面做了研究,通过扫描电镜(SEM)、X 射线衍射(XRD)、红外(IR) 光谱、热重分析(TGA)、H₂ 程序升温还原(H₂-TPR)、Brunauer-Emmett-Teller (BET)比表面积等技术深入探究SnO₂中空微纳米球的结构, 并对比中空SnO₂与实心粒子的氧化还原特性. BET和H₂-TPR显示将SnO₂制备成微纳米空心球后其比表面积增大, 表面氧空位明显增多, 氧化活性明显提高. 从IR 及XRD推断核-壳结构形成机理, 进而优化出简单合理的实验方案, 获得表面光滑、结构致密, 包覆厚度可控的SnO₂中空微纳米球.     

均匀共沉淀法制备钛酸钡-钡铁氧体核-壳结构粒子

用均匀共沉淀法制备了钛酸钡-钡铁氧体核-壳粒子, 研究了沉淀反应温度、尿素/金属离子摩尔比值(R)和BaTiO₃浓度对核-壳粒子形貌和结构的影响, 探讨了钛酸钡-钡铁氧体核-壳粒子在焙烧时的形成过程及其磁性能. 采用透射电子显微镜(TEM)、X射线衍射(XRD)分析仪对钛酸钡-钡铁氧体前驱物核-壳粒子及钛酸钡-钡铁氧体核-壳粒子的形貌和结构进行了表征, 采用振动样品磁强计(VSM)研究了钛酸钡-钡铁氧体核-壳粒子的磁性能. 结果表明: 当沉淀反应温度为100 °C, R为180, BaTiO₃浓度为2.5 g·L^-1时, 金属离子沉淀完全, 得到的钛酸钡-钡铁氧体前驱物核-壳粒子包覆层均匀、完整、光滑, 厚度约为10 nm. 过高的温度和R值都会导致大量独立颗粒杂质的生成; 随着BaTiO₃浓度的增大, 包覆层厚度有减小的趋势. 当焙烧温度为900 °C时, 壳层中开始形成BaFe₁₂O₁₉相, 其形成过程为晶态的α-Fe₂O₃和BaCO₃首先生成中间相BaFe₂O₄, 然后由BaFe₂O₄和α-Fe₂O₃反应得到最终的BaFe₁₂O₁₉. 当焙烧温度为1000 °C时, 壳层完全转化为BaFe₁₂O₁₉相. 随着焙烧温度从900 °C升高到1000 °C, 所得BaTiO₃-BaFe₁₂O₁₉核-壳粒子的饱和磁化强度从16.5 A·m²·kg^-1增加到39.5 A·m²·kg^-1, 矫顽力从340 kA·m^-1略微降低到316 kA·m^-1.     

三维有序SiC空心球的制备及表征

以三维有序多孔碳为模板, 以聚甲基硅烷(PMS)为前驱体, 经过前驱体的渗入、交联和陶瓷转化以及多孔碳模板的烧除, 制备了长程三维有序SiC空心球. 所制备的SiC空心球的外径(135-896 nm)、 球壳厚度(14-79 nm)、 BET比表面积(50.8～5.0 m2/g)及微孔体积(0.265～0.038 cm3/g)受不同孔径的多孔碳模板(150-1 000 nm)或不同前驱体浓度的控制. 所制备的SiC空心球以hcp结构排列成长程三维有序的序列.     

形貌转录法制备Ag-P(AM-co-MAA)复合微球

以反相悬浮聚合技术合成的丙烯酰胺(AM)和甲基丙烯酸(MAA)共聚高分子微凝胶P(AM-co-MAA)为模板,结合反胶束法制备得到Ag3PO4-P(AM-co-MAA)复合微球,并将其分散于乙醇溶剂中通过化学还原Ag3PO4-P(AM-co-MAA)复合微球制备得到粒径为几十微米,具有表面图案,且结构为核-壳型的Ag-P(AM-co-MAA)复合微球材料.能量散射X射线(EDX)谱表明壳化学组成以金属银为主,核以高分子模板为主;扫描电子显微镜(SEM)观察结果表明银-高分子复合微球的表面形貌与其前驱体类似,且可以通过选择模板、改变模板组成、调整金属难溶银盐沉积量等因素加以调控;X射线衍射(XRD)分析表明前驱体复合微球表面Ag3PO4全部转化为单质银.生物抗菌实验表明该类微球材料对大肠杆菌、金黄色葡萄球菌均具有较强的抑制作用.     

模板法合成核壳功能材料

模板法制备核壳功能材料是材料科学研究领域的一大热点引起了广泛的关注.本文结合本课题组在有机-无机核壳复合纳米粒子(空心球)领域的研究,较系统地评述了目前国内外利用模板法制备核壳粒子的研究进展,并概述了核壳纳米粒子(空心球)的发展前景和应用领域.     

三维有序介孔/大孔TiO2微球的制备、表征及光催化性能

以聚甲基丙烯酸甲酯微球为模板,分别以钛酸四丁酯和四异丙醇钛为钛源,通过溶胶-凝胶法辅助模板法制得TiO2纳米微球前驱体,并用程序升温控制其焙烧温度,最终成功制得了具有三维有序介孔/大孔复合结构的TiO2微球.以罗丹明B(RhB)为模型污染物,探索了以不同钛源制备得到的介孔/大孔复合TiO2微球的光催化性能;并采用XRD、SEM、TEM、UV-vis DRS、比表面积测试、光催化性能测试等对样品的晶粒尺寸、物相、形貌、光吸收、比表面积及性能等进行了分析.结果表明,运用溶胶凝胶法辅助模板法能够合成结晶度高、形貌规整、比表面积大、光催化活性良好的锐钛矿相TiO2微球.     

以微凝胶模板合成P(AM-co-DMC)/SiO_2杂化粒子

以聚(丙烯酰胺-co-甲基丙烯酰氧乙基三甲基氯化铵)[P(AM-co-DMC)]微凝胶为模板,TMOS为硅前驱体,中性水环境下合成了一系列P(AM-co-DMC)/SiO2有机-无机杂化粒子.对杂化粒子的大小、形态及表面形貌等进行研究,发现微凝胶对杂化粒子的形态和大小起主导作用,SiO2在模板上沉积,即使经过灼烧依然保持模板的形态;TMOS的用量对杂化粒子的性质也有重要影响——用量少时,得到的杂化粒子表面粗糙,增加用量会使表面变得光滑.杂化粒子经过灼烧后,表面会变得更加粗糙.     

苯乙烯和N-乙烯基吡咯烷酮共聚物/Ag复合微球的制备及性能研究

首先用无皂乳液聚合法制备了单分散聚苯乙烯(PSt)乳液,以此为种子乳液,使用N,N-亚甲基双丙烯酰胺(MBA)为交联剂,过硫酸钾(KPS)为引发剂,进行苯乙烯和N-乙烯基吡咯烷酮(NVP)共聚合制备了以PSt为核、St和NVP共聚物为壳的具有核-壳结构的聚合物微球(P(St-NVP)).以此微球为模板通过化学沉积法得到了粒径分布均匀、单分散的P(St-NVP)/Ag复合微球.傅里叶红外光谱、X-射线衍射、扫描电镜、透射电镜、激光粒度仪和紫外-可见光谱对复合微球的结构、形貌、物相及催化性能进行了表征.结果表明,P(St-NVP)/Ag复合微球具有规则的球形结构,粒径在400～700 nm之间,随交联剂浓度或种子乳液浓度的增加,复合微球粒径减小.粒径在十几个纳米左右的银粒子均匀分布在微球表面和内部.载银复合微球在NaBH4还原4-硝基苯酚为4-氨基苯酚的模型反应中表现出较高的催化活性.     

Fabrication and biocompatible characterization of magnetic hollow capsules

Monodispersed Fe3O4/polypyrrole （PPy） hollow particles were synthesized via controllable in-situ deposition and polymerization techniques using poly（styrene-co-acrylic） （PSA） latex as template. Field-dependent magnetization plot illustrates that the capsules are superparamagnetic at 300 K. FTIR spectrum confirms that the myoglobin （Mb） molecule adsorbed on the surface of Fe3O4/PPy hollow particle essentially retains its native structure. Furthermore, direct electrochemistry of Mb can be realized on Fe3O4/PPy capsules modified pyrolytic graphite disk electrode, which indicates that the magnetic conductive polymer capsules can promote the electron transfer of protein.     

Facile Fabrication of Monolayered Hollow Submicrospheres of PANI on Surfaces of Modified Polymer Films

Summary: A novel strategy was developed in order to prepare monolayered polyaniline (PANI) submicrospheres on polymer substrates. The strategy involved two main steps, i.e., photografting of acrylate acid (AA) onto the surface of a polypropylene (PP) film, and subsequent oxidative polymerization of aniline on the grafted surface. It was found that the PANI monolayered hollow submicrospheres were immobilized on the surface of the PP film when the molar ratio of AA to aniline was about 1:1.6. A possible formation mechanism of the hollow PANI submicrosphere iss discussed.     

合成条件对径向有序介孔二氧化硅中空亚微米球的形貌和结构的影响

本文以硬模板与软模板结合的双模板方法(十六烷基三甲基溴化铵(CTAB)为介孔模板,聚苯乙烯(PS)球为中空模板),通过自组装制备出有良好分离性和单分散性且具有径向介孔的二氧化硅中空亚微米球.研究表明CTAB、TEOS的用量,催化剂的种类对二氧化硅中空亚微米球的形貌、壁厚、产品纯度等都有很大的影响.在保持其它实验条件不变的情况下,通过分别单独调节CTAB和TEOS的用量或同时调节CTAB和TEOS的用量,得出最佳原料配比是:TEOS/CTAB/NH3/乙醇/水的摩尔比是1:0.27:9.8:304:2955,TEOS/聚苯乙烯球的质量比是4/1.催化剂的种类对中空亚微米球的形貌也有较大影响,当NaOH(浓度为1 mol/L)的用量为0.05—0.10 mL时,生成由小粒子聚集而成的亚微米球;随着NaOH用量增大到0.10—0.20 mL,小粒子逐渐粘合在一起,亚微米球表面逐渐变光滑;进一步增大NaOH用量为0.20—0.30 mL则导致杂质小粒子的出现.在实验结果和文献报道的基础上,讨论并提出了径向有序介孔二氧化硅中空亚微米球的形成机理.     

简易合成纳米多层级镍中空亚微球及其催化苯酚加氢的研究

采用简易一锅法, 在十二烷基硫酸钠-聚乙烯吡咯烷酮水溶液中, 利用水合肼在65 ℃下还原Ni²⁺制备镍纳米材料, 并对其表面形貌和内部结构进行了表征. 结果表明, 该镍纳米材料是壳层中具有大量介孔的中空亚微球, 且表面呈现出松针状叠合的特殊形貌, 因此是纳米多层级结构, 较厚的壳层使其整体类似于封闭的鸟巢状. 以此镍中空亚微球催化苯酚选择性加氢反应, 150 ℃催化反应4 h苯酚的转化率接近100%, 主产物环己醇的选择性高达90%以上. 该镍中空亚微球循环使用20次催化活性基本没有下降, 而且循环使用20次之后的催化剂曝露于空气中表面未被氧化, 基本不会影响其催化活性, 表明该镍中空亚微球具有高的催化活性和优良的循环稳定性能, 有望作为良好的床层催化剂使用.     

Characterization of latex particle arrays by gas adsorption

Assemblies of colloidal particles are frequently used in novel applications, and this requires nondestructive methods allowing overall characterization of the sample and collection of information about the quality of the arrays. From suspensions of polystyrene, poly[styrene-co-(2-hydroxyethylmethacrylate)], poly[styrene-co-acrylic acid], and poly[styrene-co-methacrylic acid], assemblies of spherical particles were obtained by elimination of the solvent in different ways-evaporation, gravity deposition, and filtration. These latex particle packings were characterized by scanning and transmission electron microscopy and by gas adsorption to determine the efficiency of packing. The surface area, total pore volume, and pore size distributions obtained from the adsorption and desorption data were related to characteristic parameters calculated for cubic close-packed spherical particles.     

Surface grafting of polymers onto inorganic ultrafine particles: Reaction of functional polymers with acid anhydride groups introduced onto inorganic ultrafine particles

The surface grafting onto inorganic ultrafine particles, such as silica, titanium oxide, and ferrite, by the reaction of acid anhydride groups on the surfaces with functional polymers having hydroxyl and amino groups was examined. The introduction of acid anhydride groups onto inorganic ultrafine particle was achieved by the reaction of hydroxyl groups on these surfaces with 4-trimethoxysilyltetrahydrophthalic anhydride in toluene. The amount of acid anhydride groups introduced onto the surface of ultrafine silica, titanium oxide, and ferrite was determined to be 0.96, 0.47, and 0.31 mmol/g, respectively, by elemental analysis. Functional polymers having terminal hydroxyl or amino groups, such as diol-type poly(propylene glycol) (PPG), and diamine-type polydimethylsiloxane (SDA), reacted with acid anhydride groups on these ultrafine particles to give polymer-grafted ultrafine particles: PPG and SDA were considered to be grafted onto these surfaces with ester and amide bond, respectively. The percentage of grafting increased with increasing acid anhydride group content of the surface: the percentage of grafting of SDA (M_n = 3.9 × 10³) onto silica, titanium oxide, and ferrite reaching 64.7, 33.7, and 24.1%, respectively. These polymer-grafted ultrafine particles gave a stable colloidal dispersion in organic solvents.     

Fabrication of hierarchical microparticles by depositing the in situ synthesized surface nanoparticles on microspheres during the seed emulsion polymerization

A general strategy for the synthesis of polymeric hierarchical microparticles containing surface nanoparticles through modified seed emulsion polymerization is proposed. This modified seed emulsion polymerization has a character that suitable amount of monomer miniemulsion is added during the polymerization. The in situ synthesized surface nanoparticles which are resulted from the monomer miniemulsion as well as the shell-forming polymer coagulate on the seed particles and therefore hierarchical microparticles are fabricated. Various polymeric hierarchical microparticles containing 20-36 nm poly(styrene-co-acrylamide), poly(styrene-co-acrylic acid), and polystyrene surface nanoparticles are synthesized following the proposed method. The advantages in the present synthesis including both the well controls in the size, the composition, and the number of the surface nanoparticles and the convenience are demonstrated. The proposed strategy is anticipated to be a general method to fabricate hierarchical microparticles and is believed to have promising application in particle surface modification.     

NMR法研究小分子在SiO2/PSA核壳复合颗粒中的扩散行为

以正己烷为探针分子,采用基于常梯度自旋回波序列的核磁共振技术(CFG-NMR)研究了小分子在SiO2颗粒和通过相转化法制备的SiO2/Poly(styrene-co-acrylic acid) (SiO2/PSA)复合颗粒中的扩散行为。根据双位点模型和分子交换的理论,采用两组份指数拟合实验得到的1H CFG-NMR信号衰减曲线,表明正己烷在SiO2颗粒和SiO2/PSA颗粒中具有两个相差一个数量级的扩散系数。在相同的扩散时间下,正己烷在SiO2/PSA颗粒中的两个扩散系数小于其在SiO2颗粒中的两个扩散系数,说明复合颗粒壳层的聚合物膜对正己烷的扩散具有阻碍作用。与此同时,通过改变常梯度自旋回波序列中的扩散时间,发现正己烷在复合粒子中的扩散系数强烈依赖于扩散时间的大小。     

Preparation of hollow composite spheres with raspberry‐like structure based on hydrogen‐bonding interaction

The hollow composite spheres with a raspberry‐like structure were prepared by a self‐assemble heterocoagulation based on the inter‐particle hydrogen‐bonding interaction between the amide groups of hollow poly (N,N′‐methylenebisacrylamide‐co‐N‐isopropyl acrylamide) (P(MBA‐co‐NIPAAm)) microspheres and the carboxylic acid groups of poly(ethyleneglycol dimethacrylate‐co‐methacrylic acid) (P(EGDMA‐co‐MAA)) nanoparticles, in which P(EGDMA‐co‐MAA) nanoparticle acted as the corona and the hollow P(MBA‐co‐NIPAAm) microsphere behaved as the core. The control coverage of the corona particles on the surface of hollow core microspheres of P(MBA‐co‐NIPAAm)/P(EGDMA‐co‐MAA) hollow composite sphere was studied in detail through adjustment of the mass ratio between the core and corona particles. The effect of the pH on the stability of the raspberry‐like hollow spheres was investigated. The polymer particles and the resultant heterocoagulated raspberry‐like hollow spheres were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Copyright © 2008 John Wiley & Sons, Ltd.