有序大孔二氧化硅微球的制备研究

采用乳液聚合法合成了单分散改性聚苯乙烯（PS）乳胶粒,利用PS乳胶粒自组装制得胶体晶体（“蛋白石”）微球,通过溶胶-凝胶模板法制备了有序大孔SiO2（“反蛋白石”）微球,通过SEM对改性PS乳胶粒、胶体晶体微球和有序大孔SiO2微球表面形貌进行了表征。结果表明,改性PS乳胶粒呈单分散性,粒径为317 nm;胶体晶体微球表面PS乳胶粒排列有序;有序大孔SiO2微球表面呈有序多孔,其孔呈六边形,孔径分布均一,约为200 nm。     

含银纳米晶TiO2有序多孔膜层的制备及其光学性能

以单分散聚苯乙烯(PS)微球为原料,水为稀释溶剂,利用垂直沉降法制备出多层PS球有序阵列模板.采用溶胶-凝胶法制备TiO2溶胶,并用胶晶模板法制备出锐钛矿型TiO2有序多孔薄膜.然后将金属银纳米晶掺入多孔膜骨架中制备出含银纳米晶的TiO2有序多孔发光薄膜.分析了掺银的TiO2有序多孔膜的形貌与结构,并研究了掺银的TiO2有序多孔膜吸附罗丹明B及量子点CdSe荧光物质的荧光增强性能.结果表明:掺银的TiO2薄膜基本呈现多孔结构并保留有一定的有序性.有序多孔骨架中银纳米晶的表面荧光增强作用可大幅度提升荧光物质的荧光性能,从而扩展了TiO2有序多孔薄膜在生物信息探测、光信息处理领域的应用.     

无皂乳液聚合制备三维有序聚合物大孔材料

采用氨催化水解正硅酸乙酯制备了单分散二氧化硅微球,通过透射电子显微镜观察微球的粒径及其单分散性。利用垂直沉积法制备二氧化硅胶体晶体,通过扫描电子显微镜观察其形貌,利用紫外-可见光分光光度计对其带隙结构进行表征。结合模板技术,采用无皂乳液聚合制得三维有序聚苯乙烯大孔材料,通过扫描电子显微镜观察结构的有序度。结果表明:聚苯乙烯大孔材料结构高度有序,形成开放的三维通道网络,为聚合物大孔材料在诸多领域的潜在应用提供了可能。     

协同组装法制备二氧化钛多孔薄膜

以聚苯乙烯微球(polystyrene sphere,PS)和超细TiO2纳米粉为原料,采用协同组装法制备了TiO2多孔薄膜.在组装过程中,TiO2纳米粉通过毛细管力可以直接组装在模板微球的间隙内.探讨了工艺参数,如:蒸发温度、TiO2含量及PS和TiO2质量比对薄膜形貌和结构的影响.结果表明:采用协同组装法可获得有序多孔的TiO2薄膜,薄膜的孔径及无机墙的厚度与TiO2含量及PS对TiO2的质量比密切相关.X射线衍射分析表明薄膜为锐钛矿结构.在350～800 nm的波长范围内薄膜的透光率可达75%以上,禁带宽度约为3.12 eV.     

以聚苯乙烯为模板制备有序大孔氧化铝

采用少皂乳液聚合法成功制备了单分散的聚苯乙烯微球,以微球自组装后的聚苯乙烯胶体晶体为大孔模板,铝溶胶为前驱体填充模板,干燥焙烧除去模板后制备了氧化铝载体。用激光粒度仪、扫描电镜、X射线衍射和氮气吸脱附对聚苯乙烯胶体晶体和氧化铝载体进行了表征。结果表明:少皂乳液聚合法制备的聚苯乙烯微球具有粒径较小(100~350 nm)、单分散性好(0.005)、收率高(约80%)等优点;自组装的胶体晶体呈规则有序排列,微球表面光滑洁净,并以此为模板成功制备了具有三维有序结构的、大孔孔径可调的氧化铝材料。     

三维有序大孔氧化钇稳定氧化锆的制备与表征

以聚苯乙烯(polystyrene, PS)胶体晶体为模板,采用柠檬酸凝胶方法制备氧化钇稳定氧化锆(yttria stabilized zirconia, YSZ)前驱体溶胶,采用浸渍-提拉方法向PS模板的空隙中填充YSZ溶胶,煅烧去除模板后成功地制备了三维有序大孔YSZ材料.研究前驱体溶胶不同浓度、浸渍次数以及煅烧条件等因素对大孔YSZ结构的影响.用扫描电子显微镜对YSZ的微观结构进行表征.结果表明:前驱体溶胶的浓度在0.3～0.4 mol/L的范围内,浸渍次数为1次或2次,煅烧温度为600℃时可以得到高度有序的大孔YSZ.     

单分散胶体颗粒的有序组装及其应用研究进展

本文综述了近1～2年来课题组在单分散胶体微球有序组装及其应用方面的研究进展.其中包括250～1300 nm宽尺寸范围单分散二氧化硅胶体微球的重力沉降自组织;旨在提高光子晶体折射率反差的TiO2/SiO2复合胶体微球的有序组装;硬模板与催化材料一步复合的二元胶体体系颗粒的有序自组装;一种高效的聚苯乙烯胶体颗粒的批量组装技术;低体积分数聚苯乙烯胶体晶体的制备;以及聚苯乙烯胶粒晶体作为可调谐三维非线性光子晶体在高开关对比的光子晶体光开关方面的应用,和作为制备有序大孔材料硬模板在大分子催化方面的应用等.     

贯通有序大孔SnO2气敏材料的制备及气敏性能

以聚苯乙烯（PS）微球为模板,氧化锡（SnO₂）纳米晶为骨架,采用颗粒模板法成功制备了贯通有序大孔SnO₂气敏材料。改变PS微球的粒径,可以调节大孔SnO₂气敏材料的大孔孔径,本文以平均粒径约284nm和356nm的PS微球制备了大孔孔径分别约为200nm和260nm的贯通有序大孔SnO₂气敏材料。对制备的样品进行了热重、X射线衍射、扫描电子显微镜和氮气吸附脱附分析。结果表明：大孔排列高度有序,孔道贯通,孔壁由SnO₂纳米晶构成。制备的大孔SnO₂气敏材料不仅具备大孔-介孔-微孔结构,而且具有大的比表面积,具备优异的气敏性能。气敏测试结果表明孔径为200nm和260nm的贯通有序大孔SnO₂在280℃的工作温度下对300mL/L的乙醇气体的灵敏度为145、245,分别是无大孔SnO₂纳米晶的2.2倍、3.7倍。     

三维有序大孔二氧化钛光催化降解有机废水研究

以聚苯乙烯(PS)为胶晶模板,一定比例钛酸四丁酯、乙醇、醋酸、盐酸和水配制的溶胶溶液为前驱体,通过浸渍和低温固化过程,使溶胶在PS模板间隙内进行填充并原位凝胶,最后通过煅烧除去模板,得到三维有序大孔(3DOM) TiO2材料.将获得的3DOM TiO2材料作为一种新型光催化剂降解罗丹明B和甲基橙有机废水,同时对其降解过程中的反应动力学进行了分析.结果表明,3DOM TiO2材料具有良好的光催化降解性能,并且降解反应复合一级动力学方程.     

聚合物模板法制备单分散多孔二氧化硅微球

聚合物模板法是实现无机材料高效制备的有效途径.本研究采用交联聚苯乙烯二乙烯基苯聚合物微球为模板,以有机硅源正硅酸四乙酯(TEOS)为前驱体,通过将硅溶胶沉积到多孔聚合物中形成聚合物和二氧化硅的混合物,再经过高温煅烧将聚合物模板去除的方法,可以方便地制备形貌可控的单分散多孔二氧化硅微球.利用扫描电子显微镜(SEM),傅里叶红外光谱仪(FHR),热重分析仪(TGA),X射线衍射仪(XRD),比表面积孔径分布测定仪(BET)对聚合物模板以及制备的二氧化硅微球进行表征.另外,对单分散多孔二氧化硅微球形成机理进行探讨.     

溶胶-凝胶制备TiO2空气净化特性研究

利用XRD等手段对以钛酸四丁酯为原料采用溶胶-凝胶法制备的TiO₂纳米粒子的表面特性及其对空气环境中乙醛的光催化降解性能进行了测定。结果表明，乙醇与钛酸四丁酯体积比、溶胶pH、加水量和焙烧温度等对催化剂降解乙醛的活性有显著影响。在实验条件范围内，较短胶凝时间制备出的纳米粉末晶粒尺寸较小，活性较高。焙烧温度不但影响TiO₂粉末的粒径，而且对晶型的组成也有影响。锐钛矿晶型的光催化活性明显高于金红石晶型，锐钛矿型向金红石型转变的临界温度在（500～600） ℃。实验得到TiO₂最佳制备条件为：V(乙醇)∶V(钛酸四丁酯)=4、溶胶pH=3.0、加水量4 mL和焙烧温度(400～500) ℃。     

Hydrothermal synthesis of titanium dioxide using acidic peptizing agents and their photocatalytic activity

We have prepared TiO₂ nanoparticles by the hydrolysis of titanium tetraisopropoxide (TTIP) using HNO₃ as a peptizing agent in the hydrothermal method. The physical properties of nanosized TiO₂ have been investigated by TEM, XRD and FT-IR. The photocatalytic degradation of orange II has been studied by using a batch reactor in the presence of UV light. When the molar ratio of HNO₃/TTIP was 1.0, the rutile phase appeared on the titania and the photocatalytic activity decreased with an increase of HNO₃ concentration. The crystallite size of the anatase phase increased from 6.6 to 24.2 nm as the calcination temperature increased from 300 °C to 600 °C. The highest activity on the photocatalytic decomposition of orange II was obtained with titania particles dried at 105 °C without a calcination and the photocatalytic activity decreased with increasing the calcination temperature. In addition, the titania particles prepared at 180 °C showed the highest activity on the photocatalytic decomposition of orange II. This paper was prepared at the 2004 Korea/Japan/Taiwan Chemical Engineering Conference held at Busan, Korea between November 3 and 4, 2004.     

Study of morphology,mechanical properties,and thermal degradation of polycarbonate‐titania nanocomposites as function of titania crystalline phase and content

Titania nanoparticles were prepared using a sol–gel method and calcination at 200°C and 600°C to obtain anatase and rutile phases, respectively. The obtained powders were used to prepare polycarbonate (PC)‐titania nanocomposites by melt compounding. The effect of different crystalline phases and amounts of titania, in the range 1–5 wt%, on the morphology, mechanical properties, and thermal degradation kinetics of PC was investigated. The results show that the filler modified the plasticity or rigidity of the polymer and influenced the degradation kinetics, in different ways depending on the type and amount of titania. POLYM. COMPOS., 2012. © 2013 Society of Plastics Engineers     

Porous titania microspheres with uniform wall thickness and high photoactivity

Highly porous titania particles were prepared by depositing thin films of titania, using alternating reactions of TiCl₄ and hydrogen peroxide, on poly(styrene-divinylbenzene) (PS-DVB) template particles via atomic layer deposition (ALD) at 77 °C. The composition of the titania films was verified by XPS analysis and the titania films were directly observed by TEM. TGA/DSC was used to study the thermal decomposition of the polymer template. Porous titania particles with uniform wall thicknesses were successfully obtained after the template PS-DVB was removed by oxidation in air at 400 °C for 24 h. Verification of the resulting porous structure of the titania particles was done by cross-sectional SEM and nitrogen adsorption–desorption analysis. Porous titania particles were treated at different temperatures. XRD analysis was used to determine the microstructure and phase transformation of titania at elevated temperatures. The photocatalytic activity of these porous titania particles was studied by methylene blue decomposition under UV light at room temperature and was found to be comparable to that of commercial anatase titania nanoparticles (~20 nm). Depositing Na₂SO₄ on TiO₂ retarded the TiO₂ phase transformation from anatase to rutile during calcination and, thus, greatly increased the photoactivity of the porous titania particles.     

Factors affecting the interfacial adsorption of stabilisers on to titanium dioxide particles (flow microcalorimetry, modelling, oxidation and FTIR studies): Nano versus pigmentary grades

A series of nano and micron particle size anatase and rutile titanium dioxide (TiO₂) were prepared with various densities of surface treatments in order to examine the influence of the particle size on the photoactivity of the titania particle surface and their degree and nature of interfacial interaction with polymer stabilisers namely, Irganox 1010 (Phenolic type) and Tinuvin 770 (hindered piperidine type). The surface characteristics of the synthesized powders were studied by Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS). The surface area was determined using the Brunauer Emmett Teller (N₂ BET) method, and particle size measurements using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The photochemical activities of the titania particles have been examined by monitoring the oxygen consumption during photo-oxidation of 2-propanol. Surface activity of the titania with stabilisers has also been examined by flow microcalorimetry (FMC) and DRIFTS in order to determine the nature of the interfacial interactions with different polymer stabilisers. Photoactivity assessment verified the higher activity of the nanoparticles. Hydroxyl groups were also found to be accountable for the higher photoactivity of the nanoparticles. The rutile crystal form conferred an inherent photostabilising effect that was further improved by surface coating with alumina. FMC studies revealed that the calcination of nanoanatase increased adsorption activity of hindered phenol and hindered amine probes, with the latter being more strongly adsorbed due to the higher basicity of the amine functionality. DRIFTS indicated adsorption may also occur through the ester functionalities. Calcination of the titania causes a reduction in the surface concentration of Ti–OH and hence a reduction in the amount of strongly adsorbed water blocking the adsorption sites and possibly bridging the amorphous primary particles on the uncalcined sample. With the calcined samples the adsorption activity was proportional to surface area. The physical and chemical nature of these intermolecular forces are assessed and discussed in relation to the potential effects on polymer stabilisation processes.     

焙烧对工业微硅粉除碳效果及结构特性的影响

采用焙烧法除去微硅粉中游离碳杂质,同时用多种表征手段研究焙烧温度对微硅粉性能影响.结果表明:碳含量随焙烧温度升高呈下降、稳定、再下降、最后稳定的阶梯型变化趋势,焙烧温度大于950 ℃,微硅粉中游离碳含量、SiO2含量以及微硅粉失重率趋于稳定,分别为0.05％、83.78％、4.82％.焙烧过程中微硅粉的性质发生了明显变化.微硅粉平均粒径随焙烧温度逐渐增大,从焙烧前的0.490 μm增大到1050 ℃焙烧2 h后的0.817 μm;微硅粉圆度随焙烧温度升高而下降,以850 ℃为界,焙烧温度低于850 ℃微硅粉保持原始的球状形貌,焙烧温度高于850 ℃微硅粉颗粒逐渐变为无规则块状;比表面积随焙烧温度升高而增大,焙烧温度大于850 ℃微硅粉开始结晶,比表面积随之迅速下降直至无法测得.     

MnO_x/RHA催化氧化NO制备工艺优化

以稻壳灰(RHA)为载体,采用等体积浸渍法制备了MnO_x/RHA催化剂,在常压固定床反应器上,考察了制备条件对MnO_x/RHA催化氧化NO活性的影响,采用XRD、SEM、EDX和XRF等方法对催化剂特征及制备条件的影响进行了分析。通过对催化剂特征的分析发现,MnO_x主要以无定形颗粒状负载在RHA内表面和断面上;除煅烧时间外,制备条件对催化剂活性有显著影响。通过对催化剂及RHA表面微观形貌和组分的分析发现,随着煅烧温度升高,RHA表面MnO_x颗粒尺寸增大,MnO_x晶体含量增加,当煅烧温度由200℃上升到650℃时,MnO_x颗粒粒径由0.1μm增大到1.0μm。随着灰化温度升高,RHA表面结构由平板状向疏松蜂窝状和细丝状转变。     

尼龙材料定型用乳液胶黏剂的研究

采用种子半连续乳液聚合的方法合成了苯丙乳液,采用傅里叶红外光谱(FTIR)、差示扫描量热法(DSC)等分析手段研究了聚合物的分子结构。FTIR和DSC表明,两种单体参与共聚反应,且没有均聚物的产生,共聚物的Tg约为36.42℃,明显高于理论值,显示了内交联作用的存在;该苯丙乳液的平均粒径为141.1 nm,且具有很好的单分散性。     

纳米TiO2光催化剂的制备及其活性研究

采用溶胶-凝胶法制备了纳米TiO₂光催化剂，通过XRD表征产物的晶相结构。在单因素试验的基础上，用正交试验法对影响催化剂活性的条件进行了优化研究，结果表明，在焙烧温度600 ℃ 、焙烧时间2.5 h和V(醋酸)∶V(水)＝1∶1.67条件下，催化剂活性最大，对次甲基蓝的降解率可以达到85.4%。