水和辛胺对ZnO多孔纳米块体孔道结构的影响

以ZnO纳米颗粒为原料, 分别用水和辛胺水溶液作为造孔剂, 利用溶剂热压方法制备了ZnO多孔纳米块体. 实验结果表明, 当以水作造孔剂时, 随着ZnO纳米粉/水(质量比)比值的减小, ZnO多孔纳米块体的孔径分布变宽, 比表面积和孔隙率增加; 加入辛胺后, ZnO多孔纳米块体的孔径分布变窄, 但比表面积和孔隙率略有减少. 随着辛胺用量的增加, 比表面积和孔隙率又同时呈上升趋势. 对ZnO多孔纳米块体进行的红外吸收测试结果表明, 在制备多孔纳米块体过程中, 水及辛胺基本上都从样品中逸出, 孔道中只有微量残留.     

反相非水乳液制备多孔聚酰亚胺微球

在Span85/N,N-二甲基甲酰胺/液体石蜡稳定反相非水乳液体系中,以均苯四甲酸酐和4,4’-二氨基二苯醚为单体,选用甲醇、二硫化碳作为致孔剂,制备多孔聚酰亚胺(PI)微球.通过SEM、量子化学模拟、粒径测试等手段考察致孔剂种类、致孔剂用量、吡啶/酸酐滴加速度及反应温度和单体浓度对致孔的影响.结果表明,选用二硫化碳、甲醇为致孔剂时所制得的微球形貌良好,但CS2为致孔剂时,所得到的微球孔道很少;而甲醇为致孔剂时,则得到了孔道明显的多孔PI微球.致孔的最佳条件为反应温度20℃,单体浓度10%,吡啶/酸酐滴加速度0.5 s/滴时,才可得到的形貌良好、分布均一的多孔PI微球.而且随着甲醇/液体石蜡的体积比增加,多孔PI微球比表面积也随着增大,最大可达29.38 m2/g.所得产物粒径分布在20~30μm之间,热稳定性良好,其起始热分解温度为517℃.     

基于普鲁士蓝电催化的三维多孔壳聚糖膜葡萄糖生物传感器的研制

利用电沉积方法对普鲁士蓝和壳聚糖/SiO2纳米粒子复合膜进行组装,用刻蚀法除去SiO2粒子,制备出孔径大小均匀的多孔壳聚糖/普鲁士蓝膜,这种三维多孔膜具有良好的微生物环境、比表面积大、孔隙率高,有利于负载更多的葡萄糖氧化酶,从而构建了一种灵敏度高、稳定性好、响应时间短、检测范围宽的葡萄糖生物传感器。     

采用静电纺丝/非溶剂致相分离制备聚丙烯腈多孔超细纤维的研究

以聚丙烯腈/二甲基亚砜/N,N'-二甲基甲酰胺三元体系为纺丝液、3℃水浴为接收介质,通过静电纺丝制备了具有纳米孔结构的静电纺聚丙烯腈多孔超细纤维.探讨了溶剂比例、接收介质、聚丙烯腈浓度、纺丝电压及接收距离等因素对纤维直径和表面孔隙率的影响.结果表明最佳制备条件为混合溶剂质量比1∶1、纺丝电压16 kV、聚丙烯腈浓度15 wt%、接收距离5 cm、纺丝速率0.7 mL/h、环境温度25℃、相对湿度40%～70%.在此条件下得到的聚丙烯腈多孔超细纤维直径在420～490 nm,平均直径468 nm,表面孔隙率3.4%,纤维内部形成大量孔径为8～30 nm的孔结构,且孔径分布均匀,孔形状相对一致.N2吸附脱附测试表明,聚丙烯腈多孔纤维的BET比表面积达43.86 m2/g,是相同直径无孔聚丙烯腈纤维比表面积理论值的6倍.通过研究聚丙烯腈/(二甲基亚砜+N,N'-二甲基甲酰胺)/水的三元相图,提出非溶剂致相分离是主要成孔机理.     

多孔β-磷酸三钙/壳聚糖/聚乙烯醇复合水凝胶的制备与性能

以NaCl为致孔剂,采用溶盐致孔法制备了多孔β-磷酸三钙/壳聚糖/聚乙烯醇（β-TCP/CS/PVA）复合水凝胶材料。 通过对比其含水率、溶胀比、拉伸强度、X射线衍射谱图、SEM和热重分析曲线,探讨了在相同环境下壳聚糖与β-磷酸三钙（β-TCP）的不同用量对聚乙烯醇(PVA)的结晶度以及对材料性能的影响。 此复合材料含水率为70%~76%。 当壳聚糖与β-TCP的质量比为2∶8时,复合材料的拉伸强度为0.56 MPa,断裂伸长率达到370%,其较好的力学性能,足以承受正常人眼压,可用作人工角膜周边支架材料。     

天然生物材料壳聚糖支架上人胚肺成纤维细胞的生长

采用不同粒度的硅胶粒子作为致孔剂，按硅胶和壳聚糖重量比9：1，制备了三组不同孔径的壳聚糖多孔支架．以无孔壳聚糖支架为参照，对多孔支架的有效孔径、吸水性进行了比较．结果表明：孔径大小由硅胶尺寸控制，吸水性随孔径增大而增大．为研究支架孔径大小对其生物相容性的影响，在系列支架上进行了人胚肺成纤维细胞的培养．细胞种植1d后，多孔支架上的细胞粘附较多，而无孔支架上的细胞伸展情况较好；细胞培养5d后，所有支架上细胞伸展情况良好，孔径越大的支架上细胞增殖越多．该研究结果将为天然生物材料壳聚糖作为组织工程支架材料的应用提供有益的指导．     

高压静电法制备多孔磁性壳聚糖微球

以壳聚糖(Chitosan, CS)为基质, 通过共混法引入四氧化三铁磁性颗粒, 以硅胶(Silicagel, S)为致孔剂, 在热的NaOH溶液中溶出硅胶致孔, 采用高压静电法制备磁性壳聚糖微球. 通过SEM观察了微球的结构和形貌, 并对微球结构和形貌的影响因素及其制备工艺进行了系统的研究, 结果表明, 高压静电法制备的磁性硅胶/壳聚糖微球粒径可通过微量进样器的针头大小来控制, 并且粒径分布均匀, 实验重复性及可控性好; 当以质量体积分数为5%的壳聚糖醋酸溶液(体积分数2％, mS∶mCS=4∶1), 用8号针头进样时, 制得直径约为600 μm, 孔洞分布均匀, 孔径约为50 μm的多孔磁性壳聚糖微球. 由于磁性多孔壳聚糖微球中含有大量的活性羟基和氨基, 因此显弱碱性, 对酸性物质和金属离子的吸附作用很好, 且可通过外加磁场进行有效分离. 磁性多孔壳聚糖微球在生物分离及污水中的酸性染料处理方面具有潜在的应用价值.     

溶出法制备多孔大粒聚四氟乙烯担体的研究

本文叙述用溶出法制备作为疏水化催化剂担体的多孔大粒 PTFE树脂。考查了制备中压制、烧结、致孔剂用量、致孔剂溶出时间等对 PTFE担体比表面积和强度的影响。     

聚乳酸与聚乳酸-羟基乙酸多孔细胞支架的制备及孔隙的表征

应用溶液烧铸致孔剂浸出技术制备了不同致孔剂用量与不同致孔剂颗粒尺寸条件下的一系列聚乳酸及不同组成的聚乳酸－羟基乙酸多孔细胞支架;用一种改进的方法－重量法测定其孔隙率;在聚乳酸－羟基乙酸多孔支架上进行了软骨细胞培养。研究结果表明,随着制备过程中致孔剂用量的增加,多孔支架的孔隙逐渐增加,而与致孔剂的颗粒大小基本无关;致孔剂的颗粒大小只影响多孔支架的孔径;在致孔剂用量及致孔剂颗粒尺寸都相同的情况下,随着共聚物中乙交酯含量的增加,孔隙率逐渐下降;软骨细胞在支架上繁殖情况良好,三周后已开始分泌细胞外基质。     

柚皮苷分子印迹膜的水相制备与识别

以柚皮苷为印迹分子,PEG为致孔剂,在水相中制备了柚皮苷分子印迹壳聚糖膜.分别讨论了交联剂、致孔剂和印迹分子的用量对印迹膜结构和性能的影响.用SEM观察了致孔剂对印迹膜形貌及孔径的影响.紫外吸收光谱分析、柚皮苷在不同体系中的溶解度变化,以及红外光谱分析的结果表明功能聚合物壳聚糖和模板分子柚皮苷间形成了氢键.膜的渗透实验结果表明,在水相中,柚皮苷分子印迹膜能有效地从新橙皮苷和柚皮苷的混合液中分离出印迹分子柚皮苷,选择透过率为11.16%.     

TiO2-SiO2复合气凝胶：常压干燥制备及性能表征

以廉价的四氯化钛和工业水玻璃为原料,通过溶胶-凝胶法制得TiO2-SiO2复合湿凝胶,用三甲基氯硅烷(TMCS)/乙醇(EtOH)/正己烷(Hexane)混合溶液对湿凝胶进行改性,常压干燥制备了TiO2-SiO2复合气凝胶.利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、红外光谱(FTIR)、X射线衍射(XRD)及N2吸附/脱附法对复合气凝胶的形貌和性质进行了分析.结果表明,TiO2-SiO2复合气凝胶具有连续多孔结构,150℃干燥后复合气凝胶的比表面积为1 076 m2·g-1,孔体积为4.96 cm3·g-1;经550 ℃热处理后,复合气凝胶仍然具有高的孔隙率,比表面积为856 m2·g-1,孔体积为3.46 cm3·g-1.吸附和光催化降解罗丹明B的结果表明,复合气凝胶同时具有较好的吸附和光催化性能,其吸附/光催化协同作用活性优于纯SiO2气凝胶和锐钛矿TiO2粉末;且重复利用四次降解率仍然可达到89%.     

Adsorption of Cu(II) on porous chitosan membranes functionalized with histidine

The ability of chitosan to form complexes with bivalent metal ions has been broadly explored in the literature. The present work investigates the influence of functionalization of macroporous chitosan membranes with histidine on their ability to remove copper ions from aqueous solution in the range of pH 4–6. The maximum adsorption capacity for Cu(II) ion was 2.5 mmol metal/g pristine chitosan membranes. Under this condition, no influence of membrane porosity was observed. However, for membranes with immobilized histidine, the porosity was shown to be a factor that affects the maximum adsorption capacity, with values ranging from 2.0 to 3.0 mmol metal/g chitosan. These results indicate that the immobilization of histidine on porous chitosan membranes presents synergy with porosity in the ability to complex Cu(II) ions. This synergy may be negative or positive, depending on the initial membrane porosity.     

Porous ZrC-carbon microspheres as potential insoluble target matrices for production of <Superscript>188</Superscript>W/<Superscript>188</Superscript>Re

New microsphere sorbents are reported, which could find application in demanding radiation environments and especially as targets for the production of nuclear medicines by neutron irradiation. An easily-synthesized Zr anionic complex was introduced into quaternary amine-functionalised polystyrene-divinylbenzene-based anion-exchange resins by batch adsorption. Upon carbothermal reduction, the precursors were converted to porous carbon matrices containing particles of ZrC and ZrO₂ polymorphs. The most phase-pure material, ZrAX-1, possessed high surface area, multi-scale porosity and high mechanical strength. Adsorption of Re and W was investigated and its possible deployment as a reusable host for the production of ¹⁸⁸W/¹⁸⁸Re is discussed.     

Versatile protonic acid mediated preparation of partially deacetylated chitin nanofibers/nanowhiskers and their assembling of nano-structured hydro- and aero-gels

The partially deacetylated α-chitin nanofiber/nanowhisker (DEChN) aqueous dispersions were prepared by alkali deacetylation. The following mechanical treatment under acidic conditions was mediated by five different organic protonic acids, including acetic acid, gluconic acid, itaconic acid, citric acid and ascorbic acid. Thereafter, these acidic DEChN dispersions were transformed into hydrogels under an alkali gas phase coagulation bath. After solvent exchange and freeze drying, the DEChN-based aerogels were prepared. Previous research showed that the kinds of acid used for the adjustment of the pH value during the fibrillation process influenced the nanofibrillation efficiency. In this study, it was discovered that the types of protonic acid also influenced the properties of the DEChN hydrogels and aerogels under the same mass concentration (0.6%) of DEChNs, including the appearance, strength of hydrogels, the pore size and specific surface area of aerogels, as well. Nevertheless, all of the hydrogels showed good mechanical strength and all of the aerogels possessed a porous nanostructure sustained by nanofibrillar networks. The highly porous chitin aerogels showed a broad size mainly distribution from 2 to 100 nm, and the specific surface area of chitin aerogels ranged from 90 to 170 m²g^?1. Although it was not clear how the types of protonic acids influenced the properties of the hydrogel and aerogel, we were able to obtain DEChN dispersions and gels by mechanical treatment of partially deacetylated chitin at acidic conditions mediated by versatile acids. In the meantime, the observed differences among the gels provided the possibility to use the acid medium to select the gels with certain mechanical strength, porosity or specific surface area for the prospective desired applications.     

Preparation and characterization of new materials based on silk fibroin,chitosan and nanohydroxyapatite

Abstract

In this paper, a series of porous nanohydroxyapatite/silk fibroin/chitosan (nHA/SF/CTS) scaffolds were successfully prepared using the freeze-drying method. The biomaterials were characterized by attenuated total reflection Fourier transform infrared spectroscopy, and mechanical testing and thermogravimetric analysis. Moreover, studies of porosity, pore size, swelling properties and in vitro degradation test were performed. Research has proved that micro-structure, porosity, water adsorption and compressive strength were greatly affected by the components’ concentration, in particular the content of silk fibroin. SEM observations showed that the scaffolds of nHA/SF/CTS are highly porous, with pore size in wide range from 25 to 300?µm which is suitable for cell growth. nHA/SF/CTS scaffolds have sufficient mechanical integrity to resist handling during implantation and in vivo loading. Both, the compressive modulus and compressive strength of the scaffold, decrease with the increase in silk fibroin content.     

Green,ultrafine cellulose-based porous nanofibrous membranes for efficient heavy metal removal through incorporation of chitosan by various electrospinning ways

Rapid global industrialization has worsened the heavy metal contamination of aquatic ecosystems globally. In this study, green, ultrafine cellulose-based porous nanofibrous membranes for efficient heavy metal removal were obtained by incorporating chitosan (CS) and using conventional and core–shell electrospinning ways. The relationship between the parameters of the electrospinning solution, the micro-morphology and porosity, the chemically active sites, the thermal stability, and the adsorption performance of the biocomposite nanofibrous membranes were analyzed. The adsorption effects of the copper ions, including the initial concentration, solution pH, and interaction time, were investigated. The results show that the average diameters of the conventional and core–shell ultrafine nanofibers with 50% and 30% CS loading are 56.22 nm and 37.28 nm, respectively. The core–shell cellulose acetate (CA)/CS biocomposite nanofibrous membranes showed the weaker thermal stability with a 48.2 °C lower maximum thermal decomposition temperature and induced the surface aggregation of more copper ions compared to the conventional one. A more uniform distribution of the chemical adsorption sites is obtained by conventional single-nozzle electrospinning than by core–shell electrospinning, which effectively promotes the adsorption performance of copper ions and decreases the surface shrinkage of the nanofibrous membranes during adsorption. The 30% CS conventional nanofibrous membranes at an aqueous solution pH of 5 showed the optimum adsorption capacity of copper ions (86.4 mg/g). The smart combination of renewable biomass with effective chemical adsorption sites, electrospinning technology that produces an interwoven porous structure, and an adsorption method with low cost and facile operation shows a promising prospect for water treatment.

     

几种方法制备的H3PW12O40/SiO2催化剂的结构和催化性能

 针对H3PW12O40(HPW)的比表面积小和不易回收利用等缺点,分别采用浸渍法、溶胶-凝胶法和以离子液体为模板剂的溶胶-凝胶法制备了HPW/SiO2催化剂,采用傅里叶变换红外光谱、 X射线衍射、 N2物理吸附和吸附氨的程序升温脱附等技术对催化剂样品进行了表征,并考察了其对苯硝化反应的催化性能. 结果表明,所制备的催化剂样品都保持了HPW原有的Keggin结构. 浸渍法制备的催化剂的比表面积(475.2 m2/g)较小,使用4次后硝基苯的收率由82.4%下降到70.7%; 溶胶-凝胶法制备的催化剂的比表面积(498.6 m2/g)居中,使用4次后硝基苯的收率由85.1%下降到79.6%; 以［emim］BF4离子液体为模板剂,采用溶胶-凝胶法制备的催化剂含有介孔结构,比表面积(558.5 m2/g)最高,使用4次后硝基苯的收率由84.7%下降到79.9%. 不同方法制备的HPW/SiO2催化剂具有较高的催化苯硝化反应活性和较好的稳定性.     

Chitosan macroporous asymmetric membranes—Preparation,characterization and transport of drugs

Chitosan macroporous membranes with asymmetric morphology were obtained by using an inorganic porogen agent (SiO₂). Chitosan/silica ratios used were 1:1, 1:3, and 1:5 w/w. A methodology to obtain asymmetric membranes with control of porosity and average pore size was proposed. The porous membranes were obtained taking advantage of the opposite solubility characteristics of chitosan and silica (4–20 μm). The membranes were characterized by SEM and water sorption capacity. The porosity was calculated by the relationship between dense and macroporous membranes. The SEM images of both surfaces and cross-section of the membranes confirmed their asymmetric morphology. Using a double-cell method, the permeability coefficients of two model drugs (sodium sulfamerazine and sulfametoxipyridazine) were determined. The effects of porous layer, drug type, concentration and temperature were evaluated. The results revealed that the increase in porosity results in significant differences in permeability and that the effects of drug concentration and bath temperature become less pronounced as porosity increases. The mass transport was analyzed in terms of pore-flow mechanism and the solution-diffusion mechanism. The results showed that the methodology was very efficient to yield asymmetric membranes with good mechanical resistance, control of porous size and dense layer thickness and that these membranes can potentially be used to the transport of drugs.     

壳聚糖季铵盐/滤纸复合膜对胆红素的吸附研究

用2,3-环氧丙基三甲基氯化铵对壳聚糖进行化学修饰,在壳聚糖的分子结构中引入季胺盐基团,提高其阳离子含量。将壳聚糖季铵盐涂在滤纸上,用戊二醛交联,制得壳聚糖季铵盐/滤纸复合膜,考察该复合膜的强度以及对胆红素的吸附性能。实验结果表明,壳聚糖季铵盐/滤纸复合膜具有良好的力学性能;对胆红素的吸附在3h基本达到平衡,其吸附量远大于壳聚糖/滤纸复合膜;适当取代度及高交联度的复合膜吸附效果较好。复合膜对胆红素的吸附量随离子强度的增加而降低;血清白蛋白的加入使吸附量下降。     

兼具高孔隙率和梯度孔隙结构的多孔钯块材的制备、表征及其电化学性能研究

钯材料广泛用于氢同位素储存和分离、催化和传感等领域.传统的负载钯催化材料具有优异的乙醇和甲醇等电化学催化氧化性能.除此之外,负载钯催化材料还具有优异的甲烷催化燃烧性能.然而,很多研究显示负载钯催化材料存在很多不足,例如在工程应用过程中不稳定,纳米颗粒会发生聚集和长大,进而引起材料性能急剧下降等.不同于钯片、海绵钯粉末和负载钯催化材料,多孔钯具有三维连通的孔隙结构,可避免团聚现象的发生.同时,多孔钯还具有一些特殊的物理化学性能.研究表明,梯度孔隙结构是一种高效的电化学催化结构.因而近年来很多研究者都致力于探索具有高孔隙率和梯度孔隙结构多孔钯块材的制备方法.已有的研究包括造孔剂法和模板法等,但上述方法制得的多孔钯块材均存在比表面积低或难以获得块体材料缺点.我们研究组发展了一种制备兼具高孔隙率和梯度孔隙结构的多孔钯块材的新方法.即通过以一定粒度的NaCl颗粒作为造孔剂放电等离子烧结制备PdAl合金复合块材,然后通过去离子水溶解获得多孔PdAl合金,最后经过在盐酸溶液中去合金化得到具有数十微米的宏观大孔和约10纳米的纳米孔等梯度孔隙结构的多孔钯块材.当造孔剂添加量为20 vol.%,制得了孔隙率高达88%且完整的多孔钯块材.对该多孔钯块材的力学性能进行了测试,其压缩强度为0.5 MPa.对该块材进行氮吸附测试,测试结果显示其比表面积达到54 m2/g.我们进一步对该多孔钯块材的乙醇电化学催化氧化性能进行了研究.对不同扫描速度下多孔钯块材在KOH(1 mol/L)+乙醇(0.8 mol/L)溶液中电催化活性进行分析.随着扫描速率从10 mV/s提高到50 mV/s,正扫描峰电流密度也逐渐提高,且峰电位向正电位方向移动.对峰电流密度和扫描速率的平方根进行拟合,发现它们之间存在明显的线性关系,表明该电催化氧化行为是一个受扩散控制的过程.随着溶液中乙醇浓度不断增加,正扫描方向乙醇氧化峰的峰电流呈现出先增大后减小的趋势.这是因为乙醇基和羟基在钯表面的竞争性吸附造成的.当乙醇浓度较高时,乙醇基会占据钯表面大量的活性位,从而阻碍和抑制羟基的吸附.此时,羟基在钯表面的吸附成为电氧化反应的控制因素.因此,只有选择合适的乙醇浓度,才能更好地发挥材料的电催化性能.当乙醇浓度为2 mol/L时,峰电流最大,达到120 mA/cm2,表明多孔钯块材具有优异的电催化性能,这与该材料的梯度孔隙结构、高比表面积和高孔隙率密切相关.进一步对多孔钯块材的催化稳定性进行研究.该多孔钯块材显示出了优异的催化稳定性,当经过50次循环后,乙醇氧化峰的峰电流仅下降到~110 mA/cm2.