以PSA-A乳胶粒为模板批量制备TiO2空心球

以表面富载马来酸羧基的聚（苯乙烯-丙烯酸酯）阴离子（PSA-A）乳胶粒为模板,硫酸钛为原料,水为分散介质,制备了PSA-A/钛水解产物核壳微球,然后在空气中适当温度下煅烧得到粒径约为450nm的TiO2空心球壳,用TG、SEM、TEM、IR和XRD对样品进行了分析表征,并研究了核壳结构形成的过程和各实验条件对陈化过程中体系pH值变化速率的影响.得出影响核壳结构的关键因素为体系的pH值变化速率,以此依据设计出钛盐浓度为1mol/L,乳胶粒浓度为230g/L的高浓度条件下批量制备TiO2空心球壳的新实验方案,最终产物保持良好的空心球结构.     

水热法制备核壳型纳米TiO2／Al2O3粉体的研究

通过一步水热制备TiO2/Al2O3核壳型纳米粉体,并且研究了pH值、水热温度和时间对核壳粉体的影响,最佳的反应条件为:制备前驱体的pH≈9.0,水热温度为260℃,水热保温时间为3.5h.产品的平均晶粒粒径小于20nm.通过XRD,TEM和SEM表征,核壳型纳米TiO2/Al2O3粉体包膜良好,且TiO2/Al2O3添加到水性乳胶漆后能提高其抗老化性能.     

SiO2空心球的制备与表面形貌调控

以聚苯乙烯(PS)微球为模板,通过水解正硅酸乙酯来包裹PS微球,制备了PS/SiO_2核壳结构微球,然后通过高温煅烧得到SiO_2空心球。利用纳米粒度仪、扫描电子显微镜、透射电子显微镜分析SiO_2空心球的粒径和表面形貌。采用控制变量法分别研究了PS微球表面电荷、pH、水和正硅酸乙酯的用量对SiO_2空心球表面形貌的影响。实验证明,以表面带正电荷的PS微球为模板,反应体系pH=11.0,正硅酸乙酯注入速度为100μL/min时,制备的SiO_2空心球表面最光滑。     

半连续PVAc/PBA核壳乳液聚合表观动力学

以聚乙酸乙烯酯 (PVAc)为种子 ,半连续加入 BA的核壳乳液聚合工艺 ,建立表观聚合动力学实验表达式 :Rpw=K .Ra,其中 K =1- 0 .0 2 Ra,研究表明加料速率严重影响聚合速率 ,引发剂量 /单体量对聚合速率的影响稍小 ,并对这种现象进行解释。讨论使用动力学系数 K判断乳液聚合过程及乳胶粒形态的方法 :K接近 1,反应处于饥饿态 ,乳胶粒是正向核壳 ;K值明显小于 1,反应处于充溢态 ,乳胶粒是反向核壳 ,是其热力学平衡形态     

核/壳乳胶粒的形态结构和粒径

本文研究了聚苯乙烯/聚丙烯酸2-乙基已酯和聚苯乙烯/聚丙烯酸丁酯核/壳乳胶粒的形态和结构,并研究了乳化剂和单体用量及加入方式对乳胶粒径的影响,结果表明乳胶粒径具有翻转核/壳结构,核/壳层之间形成了接枝共聚物。乳胶粒径随壳单体用量的增加而增加,而壳单体的加入方式对乳胶粒径影响较小。     

CdS空心微球的制备与表征

以不同粒径的苯乙烯-丙稀酸(酯)共聚物(PSA)乳胶粒为模板,制备出均匀的PSA/CdS核壳复合结构的微球,用有机溶剂溶去模板PSA后,分别制备了不同粒径的CdS空心微球.透射电镜分析结果表明,以直径250、340和600nm的PSA乳胶粒为模板,所得CdS空心球的粒径均匀,直径分别为340、450和800nm.紫外可见吸收光谱显示3个CdS空心球样品的最大吸收分别为480nm、410nm和485nm.     

反应性乳化剂存在下无皂纳米TiO_2苯丙复合乳液的合成及表征

在反应性乳化剂SE-10N存在下,采用预乳化半连续种子乳液聚合工艺合成了无皂纳米TiO2/苯丙复合乳液,通过正交实验优化了合成工艺条件,并对复合乳液的性能进行了测试。结果表明,所制得的复合乳液稳定,其涂膜耐水性和硬度均优于同组成的有皂复合乳液,涂膜铅笔硬度可达到2H级,且纳米TiO2的加入提高了无皂苯丙乳液涂膜的耐热性。对复合乳液进行透射电镜和动态光散射分析,结果表明无皂复合乳液乳胶粒的平均粒径为80 nm,且具有以纳米TiO2为核、聚合物为壳的异常型核/壳结构。     

纳米结构氧化镁空心球壳的制备及吸附镍离子性能研究

以Pickering乳液的液滴为模板制备纳米结构MgO空心球壳,用SEM、XRD、BET等对空心球壳进行了表征,探讨了其形成机理,并考察了纳米结构MgO空心球壳对水中Ni2+的吸附性能。结果表明,MgO空心球壳为方镁石结构,比表面积为28m2/g;其平均粒径为63μm,表面由平均宽度为65nm的纳米片层构成。Pickering乳液油水界面的部分MgO通过水化反应转变成Mg(OH)2,复合在未反应的MgO粒子上,形成MgO/Mg(OH)2空心球壳;MgO/Mg(OH)2空心球壳经焙烧后得到纳米结构MgO空心球壳。当纳米结构MgO空心球壳用量为0.4g/L时,溶液(初始浓度25mg/L)中Ni2+的去除率为98.3%。     

普通乳液聚合法制备丙-苯纳米核壳乳液

文中通过预乳化-半连续的加料工艺制备出了以聚丙烯酸丁酯为核,聚苯乙烯-甲基丙烯酸甲酯为壳的丙-苯纳米核壳乳液,分析了这种乳液聚合的方法制备纳米乳液的机理。通过粒度分布仪测定的乳胶粒的粒径分布为93.4 nm～95.6 nm,分布很窄,乳胶粒的平均粒径为94.5 nm;通过透射电境(TEM)对乳液进行观察,所制的丙-苯纳米乳胶粒具有明显的正向核壳结构,实验证明这种核壳结构是稳定的。     

聚醋酸乙烯酯反向核壳结构乳胶粒制备及形成机制

以马来酸酐(MA)作为接枝共聚单体,亲水性的聚醋酸乙烯酯(PVAc)为核,疏水性的聚苯乙烯(PSt)为壳,成功构建出一种新颖的PVAc-MA/PSt反向异形核壳结构乳胶粒,从而解决了因竞聚率差异大而无法实现醋酸乙烯酯(VAc)与苯乙烯(St)复合的难题。同时,利用接枝共聚所形成的过渡层,能够很好地抑制核壳翻转,从而成功地解决了反向核壳结构乳胶粒容易发生核壳翻转的问题。所制备出的反向核壳结构乳胶粒子平均粒径为330 nm左右,粒径大小均一。通过热力学分析发现所制备的乳胶粒呈明显的相分离结构,且存在PVAc-MA-PSt过渡层结构;乳胶粒的形貌随着MA含量的变化发生明显的衍变趋势,且粒子形貌变化可控。提出了PVAc-MA/PSt反向核壳乳胶粒子的形成机制。     

Preparation and characterization of Y2O3 hollow spheres

Y₂O₃ hollow spheres are prepared by coating the anionic poly (styrene-methyl acrylic acid) (PSA-A) latex with an amorphous yttrium layer and subsequent calcining at elevated temperatures in air. The aging temperature, aging time, the concentrations of Y(III) and urea are systematically varied to establish the optimum conditions for the formation of the coating shell. Zeta potential measurement, transmission electron microscopy, scanning electron microscopy, X-ray diffraction and infrared measurements are used to characterize the PSA-A latex, core-shell spheres and Y₂O₃ hollow spheres. A mechanism for the formation of the PSA-A/yttrium compounds core-shell spheres is suggested. The key factor to prepare smooth-coated spheres is obtained.     

Preparation of PS/TiO2 core-shell microspheres and TiO2 hollow shells

PS/TiO₂ core-shell microspheres were prepared by a hydro-thermal method at 105°C. Different-sized PS/TiO₂ core-shell microspheres were obtained with various PS cores, which were prepared by emulsion polymerization and seeds polymerization. Furthermore, intact hollow TiO₂ shells with different shell thickness were obtained by calcining PS/TiO₂ core-shell microspheres at 600°C. Light scattering of core-shell microspheres and hollow shells was tested.     

Synthesis and photocatalytic oxidation properties of titania hollow spheres

The hollow spheres of anatase TiO₂ with higher photocatalytic activity have been fabricated by spherical CaCO₃ nanoparticles as a template, and titanium sulfate (Ti(SO₄)₂) as a precursor, and the CaCO₃ templates were dissolved subsequently in dilute HNO₃ solution. The TiO₂ hollow spheres samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and N₂ adsorption-desorption isotherms. The characterization results indicate that as prepared TiO₂ hollow spheres sample was transformed to anatase phase in calcined at 400 °C, and the anatase TiO₂ hollow spheres have a higher specific surface area and show much better photocatalytic activity than commercial P25 in the photodegradation of Rhodamine B under the UV irradiation.     

One-pot synthesis of intestine-like SnO2/TiO2 hollow nanostructures

In the present study the intestine-like binary SnO₂/TiO₂ hollow nanostructures are one-pot synthesized in aqueous phase at room temperature via a colloid seeded deposition process in which the intestine-like hollow SnO₂ spheres and Ti(SO₄)₂ are used as colloid seeds and Ti-source, respectively. The novel core (SnO₂ hollow sphere)-shell (TiO₂) nanostructures possess a large surface area of 122 m²/g (calcined at 350 °C) and a high exposure of TiO₂ surface. The structural change of TiO₂ shell at different temperatures was investigated by means of X-ray diffraction and Raman spectroscopy. It was observed that the rutile TiO₂ could form even at room temperature due to the presence of SnO₂ core and the unique core-shell interaction.     

超分子水凝胶模板法制备项链状TiO2纳米颗粒

以钛酸四丁酯为钛源,以一种水性凝胶剂,3-{[(2S)-2-(十八酰胺基)-3-苯丙基]酰胺基}丁羧酸四乙胺盐(简记为TC18PheBu)在水溶液中自组装形成的聚集体为模板,经溶胶-凝胶缩聚,煅烧得到一种项链状TiO2纳米颗粒.FE-SEM分析表明所制得的项链状TiO2纳米颗粒直径约为200～400nm.采用FT-IR技术探讨了TiO2纳米颗粒形成机理.即在钛酸四丁酯水解形成的带负电的低聚物与TC18PheBu中季铵盐正离子之间,通过静电相互作用自组装形成纳米颗粒.XRD图谱表明TiO2纳米颗粒为锐钛矿晶型二氧化钛.     

不同介质中水热合成纳米TiO2粉体及其光催化性能研究

以钛酸四丁酯为原料, 采用水热法分别以蒸馏水、有机小分子化合物(正丁醇、丙二酸和乙二胺水溶液)和无机酸(HNO₃、H₂SO₄和HCl)为介质合成了TiO₂纳米粉体. 通过XRD和TEM对所得TiO₂粉体进行了表征, 研究不同介质对所得TiO₂粉体的晶相组成、颗粒尺寸及形貌的影响. 结果表明: 以蒸馏水为介质时所得锐钛矿TiO₂的颗粒尺寸分布不均匀; 有机化合物抑制锐钛矿型TiO₂各向异性生长趋势的能力为: 正丁醇>丙二酸>乙二胺; 相同实验条件下, HCl、H₂SO₄及HNO₃体系中分别获得金红石、锐钛矿及锐钛矿和金红石混晶TiO₂. 光催化降解甲基橙的研究表明, 锐钛矿和金红石混晶TiO₂的光催化活性要高于纯锐钛矿结构; 纯金红石型TiO2的光催化活性最差.     

铈掺杂TiO2/Ti光电极制备及可见光下光电催化性能的研究

采用阳极氧化法制备铈掺杂TiO2／Ti光电极，用SEM、XRD、XRF、XPS和UV／VIS／NIR对光电极的性能进行表征，并对其可见光照射下的光电催化性能进行了测试．研究结果表明：在成膜电压为160V，电流密度为100mA／cm^2，Ce（NO3）3浓度为960mg／L条件下制备的铈掺杂TiO2／Ti光电极在降解罗丹明B的实验中表现出良好的光电催化活性．     

Novel triethanolamine assisted sol-gel synthesis of N-doped TiO2 hollow spheres

A facile preparation of N-doped anatase TiO₂ hollow spheres in sub-micron size with good morphology was developed in this work. Polystyrene latexes in size of 470 nm were used as the templates to fabricate polystyrene/TiO₂ core-shell spheres in the sol-gel process. Here the ammonia/triethanolamine positive/negative catalyst pair was first employed to control the coating of TiO₂ onto the surface of the PS templates. And synchronously triethanolamine served also as the N source. The N-doped TiO₂ hollow spheres with good morphology were first obtained here after calcinations of the core-shell spheres. It was proved that the hollow spheres have distinct visible light response from 390 to 600 nm. The content of the N doping could be easily adjusted by changing the amount of triethanolamine added and the optical response of TiO₂ hollow spheres shifted more to the visible light as the content of the N doping increasing. The N doping could increase the separation efficiency of the photoinduced electron and hole, so the intensity of photoluminescence decreased obviously with increased content of the N doping.     

纳米结构的空腔二氧化硅微球的制备与缓释行为

以单分散聚苯乙烯(PS)微球作为胶体模板,采用层层静电自组装技术,交替组装聚电解质聚二烯丙基二甲基氯化铵[poly(diallyldimethylammonium chloride),PDDA]和二氧化硅纳米颗粒(10和20nm),得到核壳型聚苯乙烯/聚电解质/二氧化硅复合微球,高温煅烧除去模板PS和聚电解质,制得空腔二氧化硅微球.TEM观察的结果显示空腔二氧化硅微球呈单分散性且内部空腔呈球形;XRD图谱显示组装的二氧化硅颗粒热处理后晶化的程度很小,仍基本保持着无定形状态;N₂等温吸附-脱附实验测得用10和20nm的二氧化硅组装成的空腔二氧化硅微球的平均孔径和比表面积分别为11nm、282.71m²·g^-1和15nm、158.17m²·g^-1. 染料的装载和释放实验分别验证了空腔二氧化硅微球的腔壁具有可渗透性和缓释性.