马铃薯淀粉基炭微球的制备及其稳定机理(英文)

以马铃薯淀粉为原料,通过空气中210℃稳定化、氮气中600℃炭化,制备了马铃薯淀粉基炭微球。其中,稳定化处理是制备过程中的关键步骤。利用热失重分析(TGA)、X-射线衍射(XRD)、X-射线光电子能谱(XPS)和差热扫描量热法(DSC),对其稳定化机理进行了研究;并利用扫描电子显微镜(SEM)对其形貌进行了表征。结果表明:当稳定化时间足够长时(如12h),所制备的马铃薯淀粉基炭微球能够保持原淀粉的颗粒形态。这是由于在稳定化过程中,马铃薯淀粉中所含结晶水的失去导致了淀粉内微晶结构的破坏,使淀粉颗粒在进一步的炭化过程中不再发生微晶的熔融过程。     

微纳分级结构碳酸钙中空微球的可控制备

以CaCl₂和Na₂CO₃为反应原料, 以聚乙烯吡咯烷酮(PVP)和十二烷基磺酸钠(SDSN)为模板剂, 在50℃采用化学沉淀反应, 干燥、煅烧后成功制备了具有微纳分级结构的CaCO₃中空微球。采用扫描电子显微镜、透射电子显微镜和X射线衍射等检测手段对所制备的样品形貌、结构进行了表征, 结果显示：所制备的微纳分级结构CaCO₃中空微球直径为4~6 μm, 壳壁由直径约60 nm的CaCO₃颗粒组成, 壳层厚度约为200 nm, CaCO₃中空微球晶相组成为方解石和球霰石的共混体。同时, 在反应温度为50℃、PVP添加量为0.4 g, SDSN浓度为0.1 mol/L的条件下, 所制备的微纳分级结构CaCO₃中空微球分散性好, 且形貌比较完整。     

淀粉基炭微球的制备及结构分析

以马铃薯淀粉为原料,采用磷酸氢二铵进行稳定化处理,然后通过炭化制得了淀粉基炭微球。采用SEM、TEM、XRD和N2吸附实验对所制得的炭微球的形貌和结构进行了表征。研究表明,实验所制备的炭微球成功地保持了原料淀粉的天然球形形貌,其碳质结构具有典型的无定形结构特点,但在其无序结构周围存在着一些炭微晶。炭微球的BET比表面积为554m2/g,总孔容为0.26cm3/g。同时,通过FT-IR对磷酸氢二铵的稳定化机理进行初步的分析,结果表明,磷酸氢二铵对淀粉的化学脱水反应具有较好的催化作用,有利于淀粉在稳定化、炭化过程中保持原有球形颗粒结构。     

高锰酸钾对炭微球表面的改性

首先采用化学气相沉积法,在氩气气氛下,以脱油沥青为原料制备了炭微球(CMSs);然后用不同浓度的KMnO4溶液对CMSs进行处理,使得CMSs表面被氧化并包覆一层MnO2;最后用草酸洗涤产物,除去MnO2。通过场发射扫描电镜对CMSs氧化前后的形貌进行观察,用X-射线衍射对产物进行结构表征,并考察了氧化前后的CMSs在水和乙醇中的分散性。结果表明:当用0.1mol/L的KMnO4氧化改性CMSs后,CMSs表面包覆了一层MnO2,形成MnO2/CMSs复合材料。经过量的草酸进行洗涤,得到的产物在水中分散效果很好,且在乙醇中也有一定分散性。氧化后CMSs的表面存在亲水活性位点,为CMSs的进一步功能修饰奠定了基础。     

二氧化钛中空微球材料的研究进展

二氧化钛中空微球材料由于具有特殊的空心结构而表现出许多独特的物理化学特性,而空心结构又取决于制备方法.综述了喷雾反应法、模板法和一步法在二氧化钛中空微球材料制备中的最新研究进展,并展望了二氧化钛空心微球材料的应用前景.     

中空型聚合物微球的应用进展

中空型聚合物微球作为一种结构特殊的微球材料,目前已在涂料、造纸、生物医药、化妆品等多个行业有着广泛的应用。本文综述了中空型聚合物微球在多个行业中的应用,并对其功能化及应用前景进行了展望。     

P(St-EA-MAA)模板法制备中空二氧化硅微球

以种子乳液聚合制得的P(St-EA-MAA)共聚物微球为模板,γ-氨丙基三甲氧基硅烷(APS)为助结构导向剂,正硅酸四乙酯(TEOS)为硅源,制备了P(St-EA-MAA)/SiO2复合微球,经高温煅烧除去聚合物模板,得到了中空二氧化硅微球。热重分析(TGA)表明模板剂的最佳脱除温度为600℃。高分辨透射电镜(HRTEM)观察显示所制得的二氧化硅微球具有典型的中空结构和良好的单分散性,其尺寸主要取决于共聚物微球的大小,通过调节微球模板的尺寸可以有效控制中空微球的大小。N2吸附-脱附曲线显示二氧化硅壁具有丰富的微孔,比表面积、平均孔径和孔容分别为117.87m2/g、1.98nm和0.21cm3/g。在制备复合微球的过程中加入一定量的CTAB可以调整中空微球的壁厚和壁的孔结构,使其比表面积、平均孔径和孔容增加到219.79m2/g、3.89nm和0.25cm3/g。     

无机中空微球的应用

中空微球是内部中空的特殊球形材料,与实心球和非球形材料相比,它具有许多特殊和优异的物理化学性质。本文中简单介绍了无机中空微球的特点和制备方法,对无机中空微球在催化剂、药物载体、树脂改性填料方面的应用做了比较全面的综述。中空微球由于其特殊的中空及介孔结构,作为催化剂时,可以提高催化活性,延长催化反应时间;作为药物载体时,可提高药物存储量,并延长缓释时间;中空微球的低密度、高比表面积使其适合作为填料,用于树脂的改性。     

中空纳米微球制备及应用的研究进展

近年来，中空纳米微球的制备极大地吸引了国内外学者的目光。空心微球具有比表面大、质轻、高的流动性、高的堆积密度、不易团聚、可包容客体分子，填充到复合材料中不易引起应力集中等多种优异特性，在生产和生活中受到越来越多的重视。就目前国内外微球制备的研究状况，综述了近年来空心微球的制备原理、方法及应用，并对其制备技术的发展作了介绍。     

炭微球制备技术的研究动态

综述了近年来炭微球制备技术的研究动态,重点阐述了几种广泛采用的制备炭微球的方法及其优缺点,并指出研制成本低、工艺简单、产品粒径小的技术是今后炭微球制备技术的发展方向.     

A novel method for preparation of hollow and solid carbon spheres

Hollow and solid carbon spheres were prepared by the reaction of ferrocene and ammonium carbonate in a sealed quartz tube at 500°C. The morphology and microstructure of the product were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The carbon spheres are amorphous and their diameters range from 0·8–2·8 μm. The shell thickness of the hollow carbon spheres is not uniform and ranges from 100–180 nm. It is suggested that ammonium carbonate is crucial for the formation of carbon spheres and its amount also influences the morphology of the product. The method may be suitable for large scale preparation of carbon spheres.     

Novel PEGylated pH-sensitive polymeric hollow microspheres

Novel PEGylated pH-sensitive poly[methacrylic acid-co-poly(ethylene glycol) methyl ether methacrylate] [P(MAA-co-PEGMA)] hollow microspheres were synthesized by a two-stage distillation precipitation polymerization. PMAA@P(MAA-co-PEGMA) core shell microspheres were synthesized by the second-stage polymerization of MAA and PEGMA, using the N,N′-methylenebisacrylamide (MBAAm) as crosslinker in the presence of non-crosslinked PMAA microspheres. The cavity was formed by selective removal of PMAA core in ethanol. The resulted PEGylated hollow microspheres were characterized with Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR). The shrink and swelling behavior under different pH was studied by Dynamic Light Scattering (DLS).     

水热碳化法制备碳微球

以糖类为原料,采用水热法制备碳微球,研究不同反应物以及反应条件对水热碳的影响。利用X射线衍射(XRD)和扫描电子显微镜(SEM)对产物碳微球的结构和形貌进行表征,并借助傅立叶红外(FTIR)和X射线光电子能谱(XPS)探讨了糖类水热碳化的反应机理。     

Template-free synthesis of NiO hollow microspheres covered with nanoflakes

α-Ni(OH)₂ hollow microspheres precursors were synthesized without any template through a solvothermal method. Hydrolyzing NiCl₂ in alkaline solution, the Ni(OH)₂ hollow microspheres covered with a disordered covering of perpendicular nanoflakes were prepared. Subsequently, the similar microstructured NiO hollow microspheres with BET area around 222.8 m²/g and specific pore volume around 0.5 cm³/g were obtained by calcining the above precursor at 250–300 °C with a slow heating rate (about 1 K/min). The effects of the surfactant and the calcining temperature on the morphology and the mesostructure of the NiO hollow microspheres were also discussed.     

Controllable fabrication of monodisperse Co-B hollow microspheres

Monodisperse cobalt-boron (Co-B) hollow microspheres were fabricated by a facile and controllable method. In this method, cobalt hydroxide (Co(OH)₂) colloids were used as templates, then electroless cobalt plating was carried out on the surface of Co(OH)₂ colloids, finally Co-B hollow microspheres were obtained by adding complexing agent to dissolve the core. The products were characterized by SEM, TEM, XRD and BET, and the results showed that the as-prepared Co-B hollow microspheres have good monodispersity, spherical shape and large BET surface area. The method proposed can be extended to obtain other metal or alloyed hollow microsperes.     

Simple synthesis of hollow carbon spheres from glucose

Hollow carbon spheres were prepared by the reaction between glucose and Zn particles at 550 °C. Scanning and transmission electron microscopies reveal that most of the spheres are about 1-2 µm in diameter, similar to the sizes of the Zn particle. The shells of the spheres are comprised of numerous hollow nanospheres with the diameter of 10-100 nm. The specific surface area of the spheres is 207 m²/g. The Zn particles act as both the reactant and the template for the micron-scale spheres, and the H₂ bubbles generated during the reaction as the template for the hollow nanospheres.     

Synthesis of carbon microspheres from urea formaldehyde resin

Carbon microspheres were synthesized through polymerization of urea/formaldehyde in the presence of formic acid as catalyst, followed by drying and carbonization in an inert atmosphere. The samples were characterized by SEM, XRD, HRTEM, elemental analysis and XPS. The obtained carbon microspheres were amorphous indicated by the results of XRD and HRTEM. The changes of nitrogen functionalities at 400-1000 °C were determined by XPS. The fraction of pyridine nitrogen and pyrrole/pyridone nitrogen decreased with increasing temperature, whereas the amount of quaternary nitrogen increased.     

Synthesis and in vitro bioactivity of novel mesoporous hollow bioactive glass microspheres

The remarkable tissue-repairing bioactivity and biocompatibility of bioactive glass make it suitable for a wide range of applications. Here, novel mesoporous hollow bioactive glass microspheres (MHBGMs) with a uniform diameter range of 2-5 µm were prepared by a sol-gel method. Structural characterization indicated that the shell of hollow sphere had a mesopore size range between 2 and 10 nm and a thickness about 500 nm. The in vitro bioactivity test indicated that the novel structure exhibited high in vitro bioactivity. The uniform microspherical morphology and mesoporous hollow structure of MHBGMs, together with their high bioactivity, turn them into a good candidate as an injectable and drug-loading biomaterial for in vivo tissue regeneration and drug control release.     

Controlled synthesis of hollow calcite microspheres modulated by polyacrylic acid and sodium dodecyl sulfonate

Hollow CaCO₃ microspheres were successfully synthesized through the precipitation reaction of Na₂CO₃ with CaCl₂ in the presence of polyacrylic acid (PAA) and sodium dodecyl sulfonate (SDS) at 80 °C. The concentration of SDS is an important factor to control the synthesis of hollow CaCO₃ microspheres. X-ray diffraction confirmed that the hollow CaCO₃ microsphere consists of calcite crystals. The “pearl-necklace model” of PAA/SDS micellar aggregates serves as the spherical templates to generate hollow microspheres of CaCO₃ crystals in the precipitation system.