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1.
采用溶胶-凝胶法,以正硅酸乙酯(TEOS)为前驱体,用脂肪醇聚氧乙烯醚(AEO)为改性剂制备结构可控的多孔SiO2干凝胶。结果表明:通过调节添加量和聚合度以及溶胶老化时间可以对SiO2干凝胶织构性质进行有效的调控;采用不同的环境气候对SiO2-AEO干凝胶进行热处理,则AEO表现出不同的热稳定性;经热处理后,AEO等有机残留物被脱除的同时,SiO2-AEO干凝胶柔性骨架得到加强,孔分布更趋集中,干  相似文献   

2.
用聚合溶胶-凝胶法制备适用于纳米陶瓷膜的SiO2聚合溶胶鲍筠赵宏宾盛世善谷景华陈恒荣熊国兴PREPARATIONOFSiO2POLYMERICSOLSFORNANOPOROUSCERAMICMEMBRANESBYPOLYMERICSOL┐GELMET...  相似文献   

3.
γ射线辐照超细铂催化剂的载体效应   总被引:5,自引:0,他引:5  
用γ射线辐射法制备了铂溶胶和粒径为5nm的超细铂粉,采用机械混合法和溶胶-凝胶法制备了一系列不同载体的超细铂催化剂,不同载体对提高CO氧化活性的顺序为:MgO〉γ-Al2O3≥ZrO2〉TiO2〉SiO2,其中,由溶胶-凝胶法制备的0.1%Pt/SiO2和0.1%Pt/TiO2的经表面积大,Pt分散度高,但活性最差,XPS结果表明部分表面Pt^0和TiO2作用生成了PtO和Ti2O3,并且Pt的分  相似文献   

4.
李彬  白玉白 《应用化学》1994,11(1):67-71
以Mg(NO3)2,Ca(NO3)2,Eu(NO3)3,Bi(NO3)3和Si(OC2H5)4为反应物,采用溶胶-凝胶法,在比较低的温度,首次合成0.701molMgO-0.175molCaO-1.25molSiO2:0.06molEu^3+,0.002molBi^3+(加入Li^+作为电荷补偿剂)发光体,得到了最佳合成条件,研究了由溶胶向凝胶转变和凝胶向发光晶体的转变过程,探讨了发光体在不同激光  相似文献   

5.
以Mg(NO3)2、Ca(NO3)2、Eu(NO3)3、Bi(NO3)3、LiNO3和Si(OC2H5)4为反应物,采用溶胶-凝胶法,在比较低的温度下,首次合成0.701moIMgO-0.175molCaO-1.25moISiO2∶0.06molEu(3+),0.002moIBi(3+)(加入Li+作为电荷补偿剂)发光体。得到了最佳合成条件。研究了由溶胶向凝胶转变和凝胶向发光晶体的转变过程。探讨了发光体在不同激发波长激发下的发光特性以及在激活剂、敏化剂不同掺杂量下的发光行为。讨论了在(Mg(a)O-SiO2基质中Bi(3+)对Eu(3+)的能量传递和敏化作用。  相似文献   

6.
程时标  金泽明 《催化学报》1999,20(2):134-138
采用ICP-AES,TEM,XRD,FT-IR和FYT-Raman等技术研究了TS-1分子筛的晶化过程。结果表明,TS-1分子筛的晶化过程从无定形SiO2颗粒开始生长,以SiO2颗粒的外表面为晶核不断发展,晶化过程的第一小时内主要以无定形的SiO2-TiO2共凝胶颗粒存在,1h后开始迅速形成TS-1的晶粒,TS-1晶粒的生成与无定形SiO2的消失同时发生,8h后基本上完成TS-1分子筛的成长,结晶  相似文献   

7.
二氧化钛基固体超强酸的结构及其光催化氧化性能   总被引:46,自引:1,他引:46  
采用溶胶-凝胶法制备了多孔性,大比表面积的SO4^2-/TiO2固体超强催化剂,运用XRD,BET比表面积测定,XPS和UV-Vis反射光谱等技术对该催化剂的结构,表面状态以及半导体特征进行了表征,并通过CH3Br,C6H6和C2H4等典型有机物的气相光催化氧化反应。  相似文献   

8.
Ni-P/SiO2催化剂晶化过程及其加氢活性研究   总被引:3,自引:0,他引:3  
采用化学还原法制备了负载型Ni-P/SiO2非晶态合金催化剂,应用ICP、BET、氢氧滴定法、XRD、SEM、XPS研究了上述催化剂在高温晶化过程中的表面结构、表面形貌和表面电子态的变化。测定了Ni-P/SiO2非晶态合金晶化前后对其液相苯甲醛加氢反应催化活性和选择性。并讨论了非晶态合金催化剂晶化过程中结构变化对催化性能的影响。  相似文献   

9.
Ce2O—TiO2/SiO2的制备及除氟性能研究   总被引:5,自引:0,他引:5  
以SiO2为基质,CeO2TiO2为包覆物质,采用溶胶凝胶法制备CeO2TiO2/SiO2表面复合物,并对所制复合物进行除氟测试。用扫描电镜(SEM)观察表面形貌,讨论实验环境、试剂用量等因素对CeO2TiO2/SiO2制备及除氟性能的影响,结果表明:nTi(OC4H9)4/nCeCl3·7H2O=1、nCH3COOH/nTi(OC4H9)4=45、nC3H8O3/nTi(O4H9)4=03、RH=95%,热处理温度110℃时,所制CeO2TiO2/SiO2对F-的吸附容量(q)为214mg/g,去除率(E)为856%。  相似文献   

10.
超临界干燥法制备SiO2气凝胶的研究   总被引:13,自引:2,他引:13  
通过溶胶-凝胶法和超临界干燥技术制得了SiO2气凝胶,研究了溶液的pH值对凝胶时间及气凝胶密度的影响,应用XRD、SAXS、TEM和等方面对气凝胶样品的结构进行了初步研究,结果表明,SiO2气凝胶是连续网络的非晶态纳米多孔固体,其基本粒子的平均直径约10nm.  相似文献   

11.
李亚娟  詹晖  黄可龙  周运鸿 《化学学报》2010,68(18):1850-1854
分别对单质硫和PABTH (polyanthra [1 ,9 ,8 -b,c,d,e][4 ,10 ,5 -b ,c ,d ,e ]bis-[1,6,6a(6a-S)trithia]pentalene)在PEO (polyethylene oxide)基聚合物电解质中的电化学性能进行了研究. 研究发现单质硫和PABTH在PEO基聚合物电解质中都存在放电产物溶解现象, 说明醚基电解液即使以聚合物形式存在(如PEO基聚合物电解质)也不能有效抑制硫电极放电产物的溶解损失. 因此, 必须设计合成具有特定结构的电解质溶剂, 以抑制硫电极放电产物的溶解. 另外, 硫及有机硫化物在PEO基聚合物电解质中的利用率较低, 这主要是由于硫及有机硫化物不是离子导体, Li在硫及有机硫化物中的扩散系数较低, 同时, 传输Li的PEO分子量较大, Li不能被有效传输至材料颗粒的内部. 因此, 全固态聚合物电解质不适合锂硫二次电池, 液态小分子电解质溶剂更有利于锂硫二次电池发挥其高比容量.  相似文献   

12.
对半结晶聚氧乙烯(PEO)/PMMA共混体系的DSC及动态力学行为研究表明:PEO在和PMMA形成半结晶PEO/PMMA共混体系后,其β转变的峰温没有明显移动;β峰只出现在淬炎的半结晶PEO/PMMA共混体系中,而在完全非晶的相容性共混体系以及退火的半结晶共混体系不出现;在β转变区,对应的模量反常地增大,对应的DSC曲线有明显阶跃。可见,半结晶PEO的β转变并不象通常所认为的源于PEO非晶区的玻璃化转变。在接受半结晶PEO及半结晶PEO/PMMA共混体系的PEO结晶区存在结晶-非晶中间相观点的基础上,认为β转变源于PEO结晶区结晶-非晶中间相的玻璃化转变过程。  相似文献   

13.
Summary: Shear‐induced phase behavior of poly(ethylene oxide‐b‐(DL ‐lactic acid‐co‐glycolic acid)‐b‐ethylene oxide) (PEO‐PLGA‐PEO) triblock copolymers in water is investigated using rheology and small‐angle neutron scattering equipped with an in situ Couette shear cell. For gels formed by the macroscopic phase separation, the steady shear experiment reveals that the flow‐induced anisotropy on a nanometer length scale at a critical shear rate and the phase separation on a larger length scale are successively induced with a further increase in the shear rate. In particular, the hard gels show a memory effect inscribed by a pre‐high shear in contrast to the soft gels.

2D SANS patterns clearly show the memory effect of the hard gels at a pre‐high shear.  相似文献   


14.
选择了甲醇、乙醇、正丙醇、乙二醇、乙二胺、乙醇胺及2 甲氧基乙醇等七种包括单官能团和双官能团共溶剂、与水组成混合溶剂,并利用荧光探针技术研究了共溶剂对环氧乙烷 环氧丙烷 环氧乙烷(PEO PPO PEO)共聚物水溶液胶束形成及其结构的影响,结果表明,一些共溶剂与水和共聚物PPO段都具有较好的混溶性,使形成胶束的CMT升高,而其它共溶剂的引入则使得形成胶束的CMT降低.从共溶剂对所形成胶束的微结构影响看,能与共聚物链有较强作用的双官能团的共溶剂和有较小分子尺寸的共溶剂有利于使形成的胶束具有较紧密的结构,在此条件下,形成胶束的紧密程度决定了胶束内微极性的大小,而与引入共溶剂的极性大小关系不大.  相似文献   

15.
Blends of poly(ethylene oxide) (PEO) of high molecular weight with poly(bisphenol A-co-epichlorohydrin) (PBE) with high epoxy equivalent were studied spectroscopically, thermally and morphologically. As similar systems of low molecular weight, a single Tg was observed for all blends, indicating miscibility. A progressive decrease in the degree of crystallinity and in the size of the PEO spherulites as the PBE is added is also observed. Quantitative analysis from FTIR spectra provided determination of specific interactions between the constituents and their variation with PEO content. Simulations were performed utilising the spectra of the pure polymers to confirm that the observed changes in the experimental spectra of the blends were due to interaction between the polymers.  相似文献   

16.
选择了甲醇、乙醇、正丙醇、乙二醇、乙二胺、乙醇胺及2甲氧基乙醇等七种包括单官能团和双官能团共溶剂、与水组成混合溶剂,并利用荧光探针技术研究了共溶剂对环氧乙烷环氧丙烷环氧乙烷(PEOPPOPEO)共聚物水溶液胶束形成及其结构的影响,结果表明,一些共溶剂与水和共聚物PPO段都具有较好的混溶性,使形成胶束的CMT升高,而其它共溶剂的引入则使得形成胶束的CMT降低.从共溶剂对所形成胶束的微结构影响看,能与共聚物链有较强作用的双官能团的共溶剂和有较小分子尺寸的共溶剂有利于使形成的胶束具有较紧密的结构,在此条件下,形成胶束的紧密程度决定了胶束内微极性的大小,而与引入共溶剂的极性大小关系不大.  相似文献   

17.
We report the synthesis and structure determination of PS-block-PEO functionalized by fluorocarbon end-group (C8F17) via an ester bridge. The synthesis was done by an anionic polymerization of PS and POE terminated by grafting 3-perfluorooctylpropanoyle chloride (C8F17-C2H4-COCl) onto PS-POE alcoholate. The structure has been characterized by a number of techniques: size exclusion chromatography, elementary analysis, UV spectroscopy, 1H nuclear magnetic resonance. Those analyses have allowed the determination of the real molar mass of the copolymers and the percentage functionalization. Because of their well-defined structure, these copolymers can be used as model compounds for the determination of structure-property relationships.  相似文献   

18.
The phase diagrams of Brij 97/(PEO)m(PPO)n(PEO)m/water/IPM quaternary systems (A L‐64: m=13, n=30; A L‐62: m=7, n=32; A L‐61: m=3.5, n=31) were determined at 25°C. The liquid crystalline phases (lamellar Lαand hexagonal H1) were investigated by means of small angle x‐ray scattering (SAXS) and rheological techniques, with comparison of composition and component effects. The lamellar phases formed in Brij 97/A L‐64 and Brij 97/A L‐62 systems array more orderly than that of Brij 97/A L‐61 system, indicated by the stronger intensity of the second reflection peak in the SAXS patterns and the higher moduli (G′ and G″) in the dynamic rheograms. In Brij 97/A L‐64/water/IPM system, all Lα phases exhibit elastic rheograms, moreover the viscous property get increased with increase in water content. On the other hand, with this change, the H1 phases show Maxwell and gel‐like rheograms in order, in which the latter shows mechanical and relaxation spectra typical of highly structured materials.  相似文献   

19.
Although the resolution of CE‐SSCP has been significantly improved by using a poly(ethyleneoxide)‐poly(propyleneoxide)‐poly(ethyleneoxide) (PEO‐PPO‐PEO; Pluronic®) triblock copolymer as a separation medium, CE‐SSCP on a microchip format is not widely applicable because their resolution is limited by short channel length. Therefore, a strategy to improve the resolution in channels of limited lengths is highly required for enabling microchip‐based CE‐SSCP. In this study, we developed a high‐resolution CE‐SSCP microchip system by controlling the width of the pluronic‐filled channel. We tested four different channel widths of 180, 240, 300, and 400 μm, and found that 300 μm showed the highest resolution in the separation of two pathogen specific markers. Potential applications of our method in various genetic analyses were also shown by using SNP markers for spinal muscular atrophy.  相似文献   

20.
A triblock copolymer of the ABA type in which both components were crystallizable was synthesized. The A block was poly(ethylene oxide), PEO, and the B block, poly(dimethyl siloxane), PDMS. Upon cooling from the melt to liquid nitrogen temperature, the PEO block crystallized at around 40°C. When the copolymer was heated from ?170°C after quenching, glass transition, crystallization and melting of the PDMS middle block were identified in the thermogram at ?117°C, ?74°C and ?42°C, respectively. The degree of crystallinity of the PDMS block was estimated from the heat of fusion to be about 27%. The growth rates of the PEO spherulites were reduced by the presence of the middle block.  相似文献   

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