纳来CoB/SiO2/PVP粉体的制备及表征

以SiO:为载体,采用浸渍化学镀法在含聚乙烯吡咯烷酮(PVP)的氛化钴溶液中制备了CoB/Si02/PVP粉体.通过X射线衍射、扫描电子显微镜、高倍透射电镜、差示扫描量热法和傅里叶变换红外分光光度计等方法对所制备的粉体的物相、组织形貌和热稳定性进行了表征.结果表明,CoB/Si02/PVP粉体是非晶态合金,具有复杂的网...     

纳米SiO2负载的过渡金属硼化物对AP热分解的催化作用

采用化学还原法制备纳米NiB/SiO2、CoB/SiO2、MoB/SiO2催化剂,通过热重-差热分析(TG-DTA)研究了其对AP热分解过程的催化作用.结果表明,负载过渡金属硼化物催化剂对AP分解的催化活性顺序为:CoB/SiO2＞NiB/SiO2＞ MoB/SiO2;加入质量分数5％的CoB/SiO2使AP高温热分解峰温度降低166.2℃;SiO2载体将CoB晶型转化推迟了 110℃左右,改善了催化剂的热稳定性.     

纳米NiB/SiO2/CTAB催化剂的制备和表征

为增加NiB粒子的多样性并拓宽其现有的应用范围,采用浸渍化学还原方法制备NiB/SiO2/CTAB(十六烷基三甲基溴化铵)粉体催化剂.通过X射线衍射仪、扫描电子显微镜(sEM)和傅里叶变换红外分光光度计等仪器对制备的NiB/SiO2/CTAB粉体的组成、物相和组织形貌进行表征的结果为:在纳米SiO2载体表面成功沉积了N...     

纳米SiO2/聚酰亚胺复合薄膜的制备及性能的研究

以工业聚酰胺酸为原料,采用直接法制备了纳米SiO2/聚酰亚胺(PI)复合薄膜,通过红外光谱表征了亚胺化前后聚合物结构的变化,利用扫描电子显微镜观察了复合薄膜中SiO2的分散情况,测试了复合薄膜的拉伸强度,研究了纳米SiO2的加入对聚酰亚胺薄膜热稳定性的影响。     

PC/纳米SiO2复合材料的热降解行为

采用熔融共混法制备了聚碳酸酯(PC)/纳米二氧化硅(SiO2)复合材料。采用X射线衍射和扫描电子显微镜研究了PC和PC/纳米SiO2复合材料的结构,采用热重分析了PC和PC/纳米SiO2复合材料的热降解行为,用Kissinger-Akahira-Sunose法研究了PC和PC/纳米SiO2复合材料的热降解动力学。结果表明:PC的内部结构没有发生变化,且纳米SiO2在基体中分散均匀;加入纳米SiO2能显著改善PC的热稳定性,且PC和PC/纳米SiO2复合材料的热降解温度均随升温速率提高呈线性增加;PC和PC/纳米SiO2复合材料的热降解活化能均随转化率升高而增加,且PC/纳米SiO2复合材料的活化能明显高于PC。     

NCC/改性纳米SiO2/PVA共混膜的制备及表征

采用共混法制备了纳米纤维素(NCC)/改性纳米二氧化硅(SiO2)/聚乙烯醇(PVA)共混膜。傅里叶变换红外(FTIR)光谱分析结果表明NCC/改性纳米SiO2/PVA共混膜的共混模式为存在氢键作用力的简单物理共混。力学性能分析结果表明NCC/改性纳米SiO2/PVA共混膜较PVA膜具有较高的拉伸强度,其拉伸强度平均值为128.41 MPa。热学性能分析结果表明NCC/改性纳米SiO2/PVA共混膜较PVA膜具有较好的热稳定性,其最大热失重温度为238℃。扫描电子显微镜(SEM)图分析结果表明NCC/改性纳米SiO2/PVA共混膜样品的表面和断面形貌较规整。     

纳米SiO2/UP原位混杂复合材料的性能

分别以正硅酸乙酯、硅溶胶、纳米二氧化硅(SiO2)粉体为前驱体,通过原位聚合方法制备了不同种类的SiO2/UP(不饱和聚酯)复合树脂.采用模压成型方法,制备了SiO2/UP原位混杂复合材料,采用静态力学和动态力学方法,研究了不同种类的SiO2UP原位混杂复合材料的力学性能和流变性能.结果表明,在3种不同SiO2/UP原位混杂复合材料中,纳米SiO2粉体(质量分数为3%)/UP原位混杂复合材料的综合力学性能最好;正硅酸乙酯/UP原位混杂复合材料耐水性能最好;纳米SiO2粉体/UP原位混杂复合材料和正硅酸乙酯/UP原位混杂复合材料适合于注塑、挤出等快速成型工艺,硅溶胶/UP原位混杂复合材料适合于模塑加工工艺.     

ZnS/SiO2核壳复合结构的制备

实验采用水热法、固相法、沉淀法三种方法来制备ZnS粉体,通过XRD测试分析表明：三种方法中水热法制备的ZnS粉体形貌特征较适合被SiO2包覆,形成核壳复合结构。核壳结构的制备采用溶胶-凝胶法,根据TEOS（硅酸乙酯）加入量的不同,设计了三组单变量实验。XRD、SEM测试结果表明：ZnS被SiO2包覆形成核壳结构后能阻碍氧化及缺陷的产生,分散性、热稳定性、光致发光性能都得到了提高;而且可以通过改变TEOS的加入量对壳层厚度进行调控。     

聚苯乙烯/二氧化硅杂化材料的原位制备

采用活性负离子聚合法和末端官能化改性技术合成三乙氧基封端聚苯乙烯,然后用溶胶-凝胶法合成聚苯乙烯(PS)/SiO2杂化材料,用红外光谱、凝胶渗透色谱、差示扫描量热法、热重分析、扫描电子显微镜对PS/SiO2杂化材料的结构和性能进行分析。结果表明:PS/SiO2杂化材料中的PS和SiO2间有化学键相连;PS/SiO2杂化材料中的w(SiO2)为25%时,SiO2是粒径约为180 nm,且粒径分布均匀、有完善球形结构的颗粒,其玻璃化转变温度比纯PS高1.3℃,热稳定性较纯PS高。     

纳米SiO2/TiO2复合粉体的制备及表征

以Na2SiO3为原料,采用非均匀成核法在纳米TiO2基体上制备了SiO2表面保护膜层,通过红外光谱、X射线光电子能谱、扫描电镜、粒径测量、BET比表面积测量分析,证实纳米TiO2颗粒表面包覆了一层均匀致密的SiO2纳米膜,而且两者是以化学键合方式结合在一起。分散性能测试表明:纳米SiO2/TiO2复合粉体的分散性能明显提高。     

SiO_2粉体表面改性及其在PET中分散性能的研究

以硅烷偶联剂(KH570)对微米、亚微米和纳米级二氧化硅(SiO2)粉体进行表面接枝改性,借助红外光谱(IR)仪、热重(TG)分析仪和X射线能谱(EDS)仪对改性前后SiO2表面结构进行了表征,采用原位聚合法制得SiO2/聚对苯二甲酸乙二醇酯(PET)复合材料,利用扫描电镜(SEM)研究了不同粒径改性SiO2粉体在PET中的分散性能。结果表明:KH570可与微米、亚微米和纳米粒径SiO2粉体发生表面接枝反应;SiO2/PET复合材料的SEM观察表明,经过KH570改性后不同粒径SiO2在PET中分散均匀性得到提高。     

Solvothermal synthesis of uniform bismuth nanospheres using poly(<Emphasis Type="Italic">N</Emphasis>-vinyl-2-pyrrolidone) as a reducing agent

Uniform bismuth nanospheres were successfully prepared from bismuth nitrate in the presence of poly(N-vinyl-2-pyrrolidone) (PVP) by solvothermal process. The product was characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, and energy-dispersive X-ray. PVP plays a critical role both as a reducing agent and a capping agent in the formation of bismuth nanospheres. Shape and size of bismuth nanospheres could be tuned by changing the employed PVP/bismuth salt ratio. It was also found the solvent had an effect on the morphologies of bismuth nanomaterials. The possible formation and growth mechanism of bismuth nanospheres were also discussed and proposed to explain the reduction step.     

超疏水/超亲油SiO2薄膜的制备和表征

采用溶胶-凝胶法以正硅酸乙酯和甲基三乙氧基硅烷为共前驱体制备纳米疏水SiO2溶胶,经十二烷基三甲氧基硅烷(dodecyltrimethoxysilane,DTMS)改性后,制备出SiO2粒子薄膜,用红外光谱分析SiO2粒子的化学组成,用透射电镜观察凝胶时间对SiO2粒子形貌的影响,用扫描电镜和接触角表征SiO2涂膜的表...     

复合氧化物TiO2/SiO2性质研究

The nanometer particles of TiO2 and TiO2/SiO2 oxides were prepared by sol-gel and supercritical fluid drying method. The properties of TiO2 and TiO2/SiO2 were characterized by means of BET(Brunner-EmmettTeller method), TEM(transmission electron microscopy), SEM(scanning electron microscopy), XRD(X-ray diffraction) and FTIR(Fourier transform-infrared) techniques. The effects of different preparation route, prehydrolysis and non-prehydrolysis, on the properties of TiO2/SiO2 oxide were also examined. Experimental results show that the thermal stability of pure TiO2 is improved greatly when it is mixed with SiO2 in nanometer level. The composite TiO2/SiO2 oxides form Ti-O-Si chemical bonds, which creates new BrSnsted acidity sites. The acidity character is related to TiO2/SiO2 chemical composition and preparation methods. The acidity of TiO2/SiO2 oxides by prehydrolysis is greater than that of by non-prehydrolysis. Ti atom is rich on the surface of TiO2/SiO2.     

The influence of PVP on the synthesis and electromagnetic properties of PANI/PVP/CIP composites

Polyaniline/carbonyl iron powder (PANI/CIP) composites with core‐shell structure were synthesized via in situ polymerization in aqueous solution of polyvinylpyrrolidon (PVP). The micromorphology, structure, and microwave absorbing property of the PANI/PVP/CIP composites were characterized by scanning electron microscopy, fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and vector network analysis. And, the modified mechanism of PVP on polymerization was discussed. The research showed that the presence of PVP was conducive to not only dispersion of CIP but also the formation coated well with PANI. PANI/CIP composites that were decorated by PVP have obviously improved on wave absorbing property compared with the composites which were synthesized without PVP. With the concentrations of 10 wt% PVP, the PANI/PVP/CIP composites show best microwave absorption, which the minimum reflection loss (RL) was −26.4 dB at 38.1 GHz and the corresponding thickness was 0.9 mm; for a thickness of 1.1 mm, an RL exceeding −10 dB was obtained in the frequency range of 27.6–39.0 GHz. POLYM. COMPOS., 36:1799–1806, 2015. © 2014 Society of Plastics Engineers     

CuNi纳米晶的可控合成及Pt/CuNi催化剂催化肉桂醛加氢性能

采用水热法制备了CuNi二元金属纳米晶。以水合肼为还原剂，探究水热合成温度、表面活性剂[乙二胺（EDA）、聚乙烯吡咯烷酮（PVP）、十六烷基三甲基溴化铵（CTAB）]对CuNi纳米晶形貌的影响。随水热合成温度的升高（60℃、90℃、120℃、150℃），Cu²⁺、Ni²⁺的还原速率加快，有利于形成Cu@Ni核壳结构。以EDA为表面活性剂时，制备的CuNi二元金属纳米晶在120℃和150℃时分别呈现花状和海胆状。此外，以CuNi纳米晶为催化剂载体，采用化学置换法负载贵金属Pt合成了Pt/CuNi三元金属催化剂。X射线粉末衍射（XRD）、扫描电子显微镜（SEM）、扫描电镜X射线能谱（SEM-EDS）、X射线光电子能谱（XPS）、高角度环形暗场扫描透射（HAADF-STEM）和元素面扫（STEM-EDS）表征结果表明，Pt/CuNi催化剂纳米结构为小岛状的Pt纳米团簇负载于CuNi纳米晶。其中，Pt/CuNi-120-EDA（120为水热合成温度，EDA为制备CuNi纳米晶时添加的表面活性剂）催化剂表面具有较丰富的缺陷位和活性位点，使其在肉桂醛加氢反应中表现出最佳的催化性能（80℃下对苯丙醇的产率达100%）。     

表面活性剂为碳源制备纳米碳化钼

以表面活性剂为碳源,通过程序升温反应法成功制备了α-Mo2C,并用粉末X-射线衍射（XRD）、扫描电子显微镜（SEM）、热失重分析（TG）和透射电子显微镜（TEM）等现代分析技术,对所制备的α-Mo2C进行了表征。结果表明：不同的表面活性剂高温分解所得碳原子或碳基作碳源,所生成的α-Mo2C的颗粒粒径明显不同。制得的α-Mo2C是六方晶,α-Mo2C的颗粒粒径达到纳米级,并且用聚乙烯吡咯烷酮作碳源生成的Mo2C颗粒粒径小于用双十八烷二甲基氯化氨作碳源生成的Mo2C颗粒粒径。     

采用二步法合成核-壳型二氧化硅/二氧化铈复合微粒

以正硅酸已酯为硅源,以氨水为催化剂,无水乙醇为溶剂,采用溶胶-凝胶法并经500℃煅烧1 h后制备了SiO2微粒,运用激光粒度分析方法研究了各原料配比对SiO2粒子大小和粒径分布的影响;再以硝酸铈为铈源,碳酸铵为沉淀剂,十二烷基苯磺酸钠为分散剂,加入SiO2微粒,用化学沉淀法,通过控制反应和焙烧条件,经300℃煅烧1 h后成功合成了核-壳型单分散球状SiO2/CeO2复合微粒.并用差示扫描量热仪/热重分析仪、X射线衍射仪、红外光谱仪、扫描电子显微镜、透射电子显微镜和X射线能谱仪等手段以及zeta电位测定对SiO2/CeO2复合微粒的结构、组成和性能进行了表征.结果表明:SiO2/CeO2复合微粒呈规则球状,粒子分布非常均匀,粒径约300～350 nm;CeO2基本上为膜包覆,伴有少量的CeO2沉积,CeO2包覆层厚度约为30nm;SiO2包覆CeO2后所得复合微粒的表面电性质发生变化,其等电点对应的pH值从2.2增大至5.5.     

Rh(0) Nanoparticles: Synthesis, Structure and Catalytic Application in Suzuki–Miyaura Reaction and Hydrogenation of Benzene

Rhodium colloids have been prepared by chemical reduction of an aqueous solution of rhodium trichloride with different aliphatic alcohols (from methanol to pentanol) in the presence of polyvinylpyrrolidone (PVP) as the stabilizing agent. The obtained Rh(0) nanoparticles have been characterized structurally by means of X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. Catalytic activity of the synthesized Rh/PVP colloids has been evidenced in the Suzuki–Miyaura coupling reaction of phenylboronic acid with bromobenzaldehyde. The choice of the reducing agent and reduction conditions enabled to obtain Rh(0) colloids showing various mean nanoparticle diameters (ranging from 3.8 to 6.0 nm) and different nanoparticle morphologies. These two factors play the decisive role from point of view of catalytic activity of the presented systems. The most active Rh/PVP catalyst, prepared using ethanol as the reducing agent, have also been applied in hydrogenation of benzene to cyclohexane, showing very high activity in this process.