共查询到20条相似文献，搜索用时 234 毫秒
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模板技术是制备介观尺度下具有多重结构材料的简单有效方法。本工作围绕纳米微球及其组装结构，一维纳米纤维及其组装结构而开展。其中重点关于核-壳结构凝胶微球的制备，并以此为模板制备包覆复合微球和中空微球，实现复合微球的形貌和特征尺寸的控制。通过化学改性对单分散聚苯乙烯胶体微粒进行处理，制备了具有核-壳结构的单分散凝胶粒子。以核-壳结构凝胶粒子为模板，制备了二氧化钛包覆聚苯乙烯核壳结构的复合粒子及其中空的二氧化钛粒子。发现在无机前体的溶胶凝胶过程中，电场能诱导复合粒子表面形成贯穿的多孔结构。同样思路，制备了二氧化硅、导电聚苯胺及其复合的核-壳结构和相应的中空微球。对聚苯乙烯胶体晶进行化学改性，制备了核-壳结构的胶体晶凝胶。以此为模板，与第二种具有响应特性凝胶进行复合，得到了敏感特性的胶体晶凝胶。并研究了此复合凝胶的形态及外场响应特性。以多孔氧化铝膜为模板，制备一维结构及其阵列体系。通过调节孔的润湿性，调节一维结构的形态（纤维或中空结构）并可调节双组分核-壳结构纤维的内外相相反转。 相似文献
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采用几种常用硅烷偶联剂以及两种自制偶联剂,分别对硅溶胶中的纳米SiO2粒子进行表面改性,之后将纳米SiO2粒子分散到含氢硅油中得到改性后的含氢硅油。考察了几种偶联剂对纳米SiO2粒子表面改性及其在含氢硅油中分散效果的影响。 相似文献
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邢立民 《内蒙古科技与经济》2009,(23):80-82,152
文章介绍了CO2超临界萃取技术的原理和工艺流程,重点对影响植物油脂萃取的主要因素,包括温度、压力、时间、CO2流量和夹带剂的选择进行了探讨,最后阐明了超临界流体萃取技术的工艺特点和发展前景。 相似文献
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《科技通报》2016,(6)
为了研究在温度小区域突变的环境下铁电纳米材料结构和形貌变化。在NaOH或KOH为矿化剂的条件下,设计温度小区域突变环境设计试验,研究矿化剂催化作用下,温度小区域突变反应环境下Bi_4Ti_3O_(12)纳米片的水热反应机理,得到了温度线区域突变因素对Bi_4Ti_3O_(12)纳米片空心球结构和形貌的影响曲线。得到试验结论为:随着温度小区域突变程度的加大,Bi_4Ti_3O_(12)纳米材料的溶解速率和成核生长速率增强,随着温度小区域突变频率的增加,Bi_4Ti_3O_(12)纳米片空心球状物表面逐渐形成纳米片状结构,纳米片不断扩大,实心球从里到外不断熟化,产生纳米片构成的壳层空心球状结构。 相似文献
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金属氧化物及其复合纳米纤维具有独特性能和潜在的应用价值,一直为人们所关注。本文提出了一种简便制备CuO/SiO2纳米复合纤维的新方法。即将静电纺丝技术与溶胶凝胶法结合,得到前驱体纤维;随后在适当的温度下热处理去除有机成分,最终得到直径150～200 nm的质量比为10%CuO/90%SiO2复合纳米纤维。使用SEM、TG-DTG、XRD、FT-IR、BET、UV-Vis技术手段对样品进行表征。SEM、TG-DTG、XRD、FT-IR结果表明该纤维的成分、形貌和晶相很大程度上受到煅烧温度的影响。BET结果表明该纤维的比表面积为141.95 m2/g,是纳米结构。光吸收测量结果发现该纤维的紫外光吸收性能随纤维晶相改变而改变。 相似文献
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通过对半代聚酰胺-胺树状大分子(PAMAM)表面酯基的胺基化反应合成了由β-环糊精修饰的树状聚酰胺-胺(PAMAM-β-CD),并通过红外光谱、核磁共振氢谱等手段对其进行了分子结构表征.为研究外围修饰的β-环糊精包合小分子的性质,采用紫外-可见光光谱测试了β-萘酚在不同PA-MAM-β-CD浓度水溶液中的紫外吸收光谱.结果表明:在修饰β-环糊精的PAMAM水溶液中,β-萘酚的紫外吸光度随主体分子浓度的变化呈现了不同区域的两种相反递变,这种规律性变化源于β-环糊精空腔高电子云密度的诱导作用. 相似文献
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聚酰胺-胺(PAMAM)类树状分子是一类高度支化、具有特定三维结构、分子尺寸和构型高度可控的树枝状大分子,独特的分子结构与物理化学性质使之在众多领域有着广泛的应用前景,并迅速成为了研究热点之一.本文采用发散法合成PAMAM,改性PAMAM后得到端基为羟基的PAMAM-OH,引发ε-己内酯(ε-CL)开环聚合到PAMAM-OH上,形成树枝状-星型聚合物PAMAM-PCL.用核磁氢谱、红外光谱、凝胶色谱等分析测试手段对其进行了结构表征,偏光显微镜及DSC对其进行性能表征,PCL链段的结晶性受到较大程度削弱.这类精细结构的共聚物由于其组成部分具有优异的生物相容性,因而可以在生物材料中有潜在的应用. 相似文献
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This report studies the surface modification of cyclic olefin copolymer (COC) by 2-methacryloyloxyethyl phosphorylcholine (MPC) monomer using photografting technique for the purpose of biointerface applications, which demonstrate resistance to both protein adsorption and cell adhesion in COC-based microfluidic devices. This is essential because the hydrophobic nature of COC can lead to adsorption of specific compounds from biological fluids in the microchannel, which can affect the results during fluidic analysis and cause clogging inside the microchannel. A correlation was found between the irradiation time and hydrophobicity of the modified substrate. Static water contact angle results show that the hydrophilicity property of the MPC-grafted substrate improves with increasing irradiation time. The contact angle of the modified surface decreased to 20 ± 5° from 88 ± 3° for the untreated substrate. The surface characterization of the modified surface was evaluated using x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR spectroscopy). Attenuated total reflection-FTIR and XPS results show the presence of the phosphate group (P-O) on modified COC substrates, indicating that the hydrophilic MPC monomer has successfully grafted on COC. Finally, it was demonstrated that cell adhesion and protein adsorption on the MPC modified COC specimen has reduced significantly. 相似文献
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通过表面引发原子转移自由基聚合技术(SI-ATRP)使聚甲基丙烯酸甲酯(PMMA)接枝于有序介孔氧化硅(MCM41)粒子的孔道内外表面,制得表面PMMA接枝的MCM41复合粒子(MCM41-g-PM-MA)。进一步利用增塑剂碳酸丙烯酯(PC)与所得的MCM41-g-PMMA共同对PMMA基聚合物电解质膜进行改性,通过溶液浇铸工艺制得PMMA基复合型聚电解质膜。着重考察了MCM41-g-PMMA填充比例、MCM41表面PMMA接枝以及温度等因素对上述体系离子电导率的影响。红外光谱(FTIR)、热重(TGA)、高倍透射电镜(HRTEM)、小角X射线衍射(SAXRD)分析结果表明:PMMA已成功接枝于MCM41粒子的孔道内外表面。交流阻抗测试、差示扫描量热分析(DSC)表明:较改性前的MCM41填充体系,MCM41-g-PMMA填充的PMMA膜具有更优的离子电导率,同时具有更佳的热稳定性能。 相似文献
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Because of their low cost, natural abundance, environmental benignity, plentiful polymorphs, good chemical stability and excellent optical properties, TiO2 materials are of great importance in the areas of physics, chemistry and material science. Much effort has been devoted to the synthesis of TiO2 nanomaterials for various applications. Among them, mesoporous TiO2 materials, especially with hierarchically porous structures, show great potential owing to their extraordinarily high surface areas, large pore volumes, tunable pore structures and morphologies, and nanoscale effects. This review aims to provide an overview of the synthesis and applications of hierarchically mesoporous TiO2 materials. In the first section, the general synthetic strategies for hierarchically mesoporous TiO2 materials are reviewed. After that, we summarize the architectures of hierarchically mesoporous TiO2 materials, including nanofibers, nanosheets, microparticles, films, spheres, core-shell and multi-level structures. At the same time, the corresponding mechanisms and the key factors for the controllable synthesis are highlighted. Following this, the applications of hierarchically mesoporous TiO2 materials in terms of energy storage and environmental protection, including photocatalytic degradation of pollutants, photocatalytic fuel generation, photoelectrochemical water splitting, catalyst support, lithium-ion batteries and sodium-ion batteries, are discussed. Finally, we outline the challenges and future directions of research and development in this area. 相似文献
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Yating Pan Yunyang Qian Xusheng Zheng Sheng-Qi Chu Yijun Yang Chunmei Ding Xi Wang Shu-Hong Yu Hai-Long Jiang 《国家科学评论(英文版)》2021,8(1)
While the surface charge state of co-catalysts plays a critical role for boosting photocatalysis, studies on surface charge regulation via their precise structure control remain extremely rare. Herein, metal-organic framework (MOF) stabilized bimetallic Pd@Pt nanoparticles, which feature adjustable Pt coordination environment and a controlled structure from core-shell to single-atom alloy (SAA), have been fabricated. Significantly, apart from the formation of a Mott-Schottky junction in a conventional way, we elucidate that Pt surface charge regulation can be alternatively achieved by changing its coordination environment and the structure of the Pd@Pt co-catalyst, where the charge between Pd and Pt is redistributed. As a result, the optimized Pd10@Pt1/MOF composite, which involves an unprecedented SAA co-catalyst, exhibits exceptionally high photocatalytic hydrogen production activity, far surpassing its corresponding counterparts. 相似文献
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本文阐述了煤的灰成分测定的方法及一些相关问题的研究,特别对煤灰中SiO2测定时一些注意问题进行了深入讨论。 相似文献
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在光学系统中,SOI(绝缘体上的半导体)上制备集成的MMI(多模干涉)型光耦合器已成为一种愈来愈引人注目的无源器件.由于Si和SiO2 之间具有大的折射率差,在SOI波导中可以采用SiO2 薄膜( <1.0 μm)作限制层,这与超大规模集成电路工艺相兼容.描述了采用SOI技术制备集成的MMI型光耦合器和光开关的设计和制造结果.业已证实,2× 2MMI MZI(多模干涉 麦赫 曾德干涉)型热光开关的开关时间小于 2 0 μs. 相似文献
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Tiantian Kong Jun Wu Kelvin Wai Kwok Yeung Michael Kai Tsun To �� Liqiu Wang 《Biomicrofluidics》2013,7(4)
We report a facile and robust microfluidic method to fabricate polymeric core-shell microspheres as delivery vehicles for biomedical applications. The characteristics of core-shell microspheres can be precisely and easily tuned by manipulating the microfluidic double emulsion templates. The addition of a shell can significantly improve the versatility as well as functionality of these microspheres as delivery vehicles. We demonstrate that the nature of the shell material plays an important role in the properties of the core-shell delivery vehicles. The release kinetics is significantly influenced by the material of the shell and other characteristics such as the thickness. For example, by adding a poly(lactic-co-glycolic acid) (PLGA) shell to an alginate core, the encapsulation efficiency is enhanced and undesired leakage of hydrophilic actives is prevented. By contrast, adding an alginate shell to PLGA core can lead to a reduction of the initial release rate, thus extending the release period of hydrophobic actives. Microfluidic fabrication enables the generation of precisely controlled core-shell microspheres with a narrow size distribution, which enables the investigation of the relationship between the release kinetics of these microspheres and their characteristics. The approach of using core-shell particles as delivery vehicles creates new opportunities to customize the release kinetics of active ingredients. 相似文献