由铜-胺氧化还原引发反应一步法简便制备TiO_2表面接枝聚甲基丙烯酸甲酯纳米杂化粒子

提出并验证了一种通过普通自由基聚合在纳米TiO2表面接枝聚甲基丙烯酸甲酯的简单方法.通过在纳米TiO2粒子表面引入伯胺分子层(纳米TiO2-NH2粒子),利用Cu2+-胺氧化还原体系实现了CuSO4催化纳米TiO2-NH2粒子表面引发甲基丙烯酸甲酯(MMA)的自由基接枝聚合,从而一步得到表面固定有聚甲基丙烯酸甲酯链的纳米TiO2杂化粒子(纳米TiO2-PMMA杂化粒子).红外光谱、热失重分析与电镜的结果都表明PMMA已经被接枝到纳米TiO2粒子表面,且接枝率随着聚合时间的延长而逐渐增大,PMMA链的引入有助于降低纳米TiO2粒子微球的团聚程度、增强与有机溶剂分子的范德华力,从而提高分散稳定性.反应溶液中没有游离均聚物形成.     

超声辐照原位乳液聚合制备P(BA-MMA-AA)/TiO_2纳米复合乳液的研究

通过超声辐照原位乳液聚合制备了稳定的丙烯酸丁酯-甲基丙烯酸甲酯-丙烯酸共聚物[P(BA-MMA-AA)/TiO2]纳米复合乳液.系统研究了乳化剂浓度,单体及TiO2用量对超声辐照原位乳液聚合反应的影响.结果表明,随乳化剂浓度增加、单体及TiO2用量的减少,聚合反应速率增高.TEM、SEM和FTIR证实了P(BA-MMA-AA)包覆在纳米TiO2表面,并与TiO2粒子有较强相互作用.用DSC、GPC和1H-NMR表征共聚产物,发现随TiO2加入,共聚物分子量降低,共聚链段中BA单元比例增加,导致聚合物玻璃化转变温度降低.     

新型茂钛催化剂合成聚乙烯-b-间规聚苯乙烯嵌段共聚物的研究Ⅱ.嵌段共聚物的分离及结构性能

将五甲基茂基三苄氧基钛 (Cp Ti(OBz) 3) 改性甲基铝氧烷 (mMAO)催化体系以顺序加料溶液法合成的乙烯与苯乙烯嵌段共聚反应产物进行沸丁酮、沸四氢呋喃 (THF)和沸氯仿等溶剂连续抽提分离 ,发现嵌段共聚物主要存在于THF和CHCl3的可溶级分中 ,嵌段共聚物的总含量占共聚产物的 2 2 8wt%～ 38 2wt% ,对THF和CHCl3可溶级分分别用 1 3C NMR、WAXD、DSC和GPC等手段进行表征 .1 3C NMR谱显示出含有支化聚乙烯链段和间规聚苯乙烯链段的嵌段共聚物特殊结构 ,WAXD谱表明嵌段共聚物因两链段的相互缠结使各自结晶度显著较低 ,由于嵌段共聚物苯乙烯链段较长、乙烯链段较短 ,DSC图谱只显示苯乙烯链段的结晶熔融峰 ,GPC曲线表明 ,单茂钛催化体系催化乙烯 苯乙烯嵌段共聚合的单一活性中心特征 .由此对Cp Ti(OBz) 3 mMAO催化体系的苯乙烯 乙烯嵌段共聚合机理进行初探     

螯合树脂研究——Ⅷ.以聚硫醚为主链的氧杂多乙烯多胺型螯合树脂的合成及其吸附性能

由聚[2′-氯乙基-2,3-环硫丙基醚]和多乙烯声胺反应,合成了四种以聚硫醚为主链的氧杂多乙烯多胺型螯合树脂,它们对贵金属离子Au(Ⅲ)、Pd(Ⅱ)、Pt(Ⅳ)、Ag~+等具有优良的吸附性能。     

TiO2纳米粒子制备方法对其光催化活性的影响

分别用胶溶法、金属醇盐水解法和低温水解法制备了TiO2纳米粒子;采用XRD和BET技术,测试了TiO2粒子的粒径、晶型及表面积。以庚烷的气相光催化氧化为探针反应,考察了不同方法、不同温度处理的TiO2粒子的光催化活性。结果表明,以胶溶法和金属醇盐水解法制备的TiO2粒子,随焙烧温度的增加TiO2粒子长大,晶型由锐钛矿向金红石型转变,光催化活性降低。用低温水解法,可在低温下制得金红石型TiO2粒子,但其催化活性很低。说明由原料和制备方法所决定的TiO2粒子的物理化学性质,影响其光催化行为。锐钛矿型TiO2粒子催化活性较金红石型TiO2好。这是由于前者的表面羟基含量较高且带隙能较大的缘故。     

光诱导聚合制备聚噻吩/二氧化钛复合粒子的结构及光催化性能

通过光诱导噻吩在TiO2的氯仿悬浮液中聚合反应,制备了聚噻吩/二氧化钛(PTh/TiO2)复合粒子,并采用比表面积分析仪、扫描电子显微镜、粒径分析仪、X射线光电子能谱、紫外-可见漫反射光谱和红外光谱对复合粒子进行了表征.结果表明,PTh/TiO2复合粒子上的聚噻吩骨架中S原子与TiO2粒子间存在强相互作用,该复合粒子对...     

CdS/TiO2复合纳米粒子的光学性质

在Brij35/正己醇/环己烷/水构成的反相微乳体系中，分别合成了CdS、TiO2纳米粒子和TiO2包覆CdS（CdS/TiO2）的复合纳米粒子.测定了它们的紫外-可见吸收和荧光光谱.结果表明， CdS/TiO2复合纳米粒子在可见光区的吸收比相应的两组分的吸收之和更强.纳米CdS和纳米TiO2均有较强的荧光.而且在相同浓度时纳米TiO2的荧光比纳米CdS的荧光更强.但在CdS/TiO2复合纳米粒子中，TiO2的荧光被淬灭，而CdS的荧光稍有降低.     

氢键接枝法抑制聚合物单链交联过程中的链间交联

当三嵌段聚合物的中间嵌段较长时,要在较高的聚合物浓度(例如:2.0 mg/mL)下交联该中间嵌段,得到纯的中间嵌段链内塌缩的聚合物单链粒子是相对困难的.其在交联过程中容易发生链间交联.因此,开发可有效抑制链间交联的方法是实现在较高聚合物浓度下制备较高纯度单链粒子的关键.选用中间嵌段较长的聚苯乙烯-b-聚(2-乙烯基吡啶)-b-聚环氧乙烷(PS1596-b-P2VP2895-b-PEO726;下标是对应嵌段的聚合度),通过在其共同溶剂N,N-二甲基甲酰胺中利用1,4-二溴丁烷交联其中间P2VP嵌段,制备出该中间嵌段链内塌缩的单链聚合物粒子.为了抑制链间交联,首先对交联反应的条件(如前驱体浓度、交联剂用量等)进行了优化,可使得高纯度单链粒子的制备浓度达到0.5 mg/mL.在此基础上,利用硬脂酸(SA)在P2VP嵌段氢键接枝的方法可进一步抑制链间交联,使得较高纯度单链粒子的制备浓度提高至2.0 mg/mL. SA的氢键接枝显著降低了交联过程中P2VP链间碰触概率,从而抑制链间交联反应的发生.同时,由于其可逆特性,SA对P2VP的氢键接枝不会对单链粒子的结构与组成产生显著影响.     

纳米TiO2/高分子复合粒子的制备及表征

用水溶性的羟丙基纤维素(HPC)对纳米TiO2进行表面包覆,得到纳米TiO2/HPC粒子,再以硫酸铈铵[Ce(SO4)2·2(NH4)2SO4]作为引发剂,在纳米TiO2/HPC粒子表面进行HPC与甲基丙烯酸甲酯(MMA)的接枝聚合,最终得到纳米TiO2/HPC-g-PMMA复合粒子,实现了纳米TiO2的有机化改性.用IR, TEM和TG对复合粒子进行了一系列的测试与表征.     

长序列乙烯-丁二烯共聚物的合成

研究了稀土催化剂催化乙烯-丁二烯的共聚合。结果表明,在封管条件下用稀土催化剂可以使乙烯-丁二烯共聚,产生高分子量聚合物。产物的溶液性质表明,不含聚乙烯均聚物,含约8％的聚丁二烯均聚物。DSC、X-射线衍射、电子显微镜和~(13)C-NMR等实验表明,所得聚合物是含长乙烯-乙烯序列的乙烯-丁二烯共聚物,其中聚丁二烯链段的微观结构以顺-1,4构型为主。共聚物中乙烯单元增加,乙烯-乙烯链段的熔点和结晶度增高,晶粒尺寸变大,晶胞参数基本不变。共聚物的力学性能表明,其生胶强度可达20—30kg/cm~2,远比聚丁二烯的强度大。     

Synthesis of dendrimer-protected TiO2 nanoparticles and photodegradation of organic molecules in an aqueous nanoparticle suspension

Dendrimer-protected TiO2 nanoparticles were synthesized by hydrolysis of TiCl4 in solutions of poly(amido amine) dendrimers (64 terminals) under cooling. The morphology of dendrimers surrounding TiO2 nanoparticles depended on the terminal groups (amine, carboxyl, hydroxy) of dendrimers. The size (4.4-6.7 nm) of dendrimer-protected TiO2 nanoparticles was slightly smaller than that (7.5 nm) of bare TiO2 nanoparticles. The photodegradation of 2,4-dichlorophenoxyacetic acid revealed that dendrimer-protected TiO2 nanoparticles are more active as a photocatalyst than TiO2 nanoparticles without protectors. This suggests that the dendrimer acts as a reservoir of photoreacting reagents besides acting as a protector of nanoparticles.     

Impact and mechanism of TiO_2 nanoparticles on DNA synthesis in vitro

The impact of TiO2 nanoparticles on DNA synthesis in vitro in the dark and the molecular mechanism of such impact were studied. The impact of TiO2 nanoparticles on DNA synthesis was investigated by adding TiO2 nanoparticles in different sizes and at various concentrations into the polymerase chain reaction (PCR) system. TiO2 nanoparticles were premixed with the DNA polymerase, the primer or the template, respectively and then the supernatant and the precipitation of each mixture were added into the PCR system separately to observe the impact on DNA synthesis. Sequentially the interaction be- tween TiO2 nanoparticles and the DNA polymerase, the primer or the template was further analyzed by using UV-visible spectroscopy and polyacrylamide gel electrophoresis (PAGE). The results suggest that TiO2 nanoparticles inhibit DNA synthesis in the PCR system in the dark more severely than mi- croscale TiO2 particles at the equivalent concentration and the inhibition effect of TiO2 nanoparticles is concentration dependent. The molecular mechanism of such inhibition is that in the dark, TiO2 nanoparticles interact with the DNA polymerase through physical adsorption while TiO2 nanoparticles do with the primer or the template in a chemical adsorption manner. The disfunction levels of the bio-molecules under the impact of TiO2 nanoparticles are in the following order: the primer > the tem- plate > the DNA polymerase.     

SiO2-TiO2中空型界面光催化剂的制备及性能

采用十八烷基三乙氧基硅烷对TiO2和核壳中空型纳米粒子SiO2-TiO2进行了壳表面疏水烷基化修饰,制备出新型界面光催化剂,并用IR和XRD进行表征.在紫外光照射下,考察了两种界面光催化剂的光稳定性,并以弱酸性黄G溶液的界面光降解为模型反应,考察了催化剂的光催化活性.结果表明,长链烷基成功接枝在了两种纳米粒子表面,且改性前后晶型无变化.与TiO2界面光催化剂相比,SiO2-TiO2界面光催化剂不仅具有优异的界面光稳定性,同时在无搅拌状态下对弱酸性黄G溶液也有良好的光催化活性.     

Controlled synthesis of highly dispersed TiO2 nanoparticles using SBA-15 as hard template

Highly dispersed TiO2 nanoparticles were successfully synthesized by a wet impregnation method using SBA-15 as hard template for confining the growth of TiO2 nanocrystals, and then calcined at 550 degrees C in muffle furnace for 2 h. The as-synthesized samples were characterized with Fourier transform infrared spectra (FTIR), Raman spectroscopy, diffuse reflectance UV-visible spectroscopy (UV-vis), powder X-ray diffraction (XRD), small-angle X-ray diffraction (SAXRD), nitrogen adsorption, transmission electron microscopy (TEM) and photoluminescence spectra (PL). It was found that SBA-15 contained abundant silanol groups after removal of triblock copolymers by ethanol extraction and could easily adsorb a great number of titanium alkoxide via chemisorption. After subsequent hydrolysis of the anchored Ti complexes and calcination of the amorphous TiO2, anatase TiO2 nanocrystals with spherical shape and uniform particle diameter of about 6 nm were formed. A blue shift was observed in UV-vis absorption spectra due to the quantum size effect of TiO2 nanoparticles. Moreover, the as-prepared TiO2 nanoparticles showed a high PL intensity due to an increase in the recombination rate of photogenerated electrons and holes under UV light irradiation.     

Enhanced photocatalytic degradation of C.I. Basic Violet 2 using TiO2-SiO2 composite nanoparticles

In this report, TiO(2) -SiO(2) composite nanoparticles were prepared by the thermal hydrolysis method using titanium tetrachloride and tetraethylorthosilicate as TiO(2) and SiO(2) precursors, respectively. The prepared nanoparticles were characterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), nitrogen adsorption/desorption and UV-Vis diffuse reflectance spectroscopy (DRS). The results indicated that, in comparison with pure TiO(2), TiO(2)-SiO(2) composite nanoparticles had a higher thermal stability, which prevents phase transformation from anatase to rutile. In addition, the TiO(2)-SiO(2) nanoparticles had a higher specific surface area, larger pore volume, greater band gap energy and smaller crystallite size. Thus, the surface area of TiO(2)-40% SiO(2) composite nanoparticles was about 17 times higher than that of pure TiO(2) nanoparticles. The photocatalytic activity of TiO(2)-SiO(2) composite nanoparticles in the photodegradation of C.I. Basic Violet 2 was investigated. The photodegradation rate of Basic Violet 2 using TiO(2)-40% SiO(2) nanoparticles calcined at 600°C was much faster than that using pure TiO(2) and Degussa P25 TiO(2) by 10.9 and 4.3 times, respectively. The higher photoactivity of the TiO(2)-SiO(2) composite nanoparticles was attributed to their higher surface area, larger pore volume, greater band-gap energy and smaller crystallite size compared with pure TiO(2).     

二氧化钛纳米微粒的制备与光催化活性

本文采用溶液－凝胶法制备了粒径为１０－２０ｎｍ左右的二氧化钛纳米微粒。用ＸＲＤ研究了二氧化钛溶胶的热处理过程,研究表明温度在４７３Ｋ－６７３Ｋ左右ＴｉＯ２向量 粒呈不规整锐钛矿结构,粒径约为１０－２０ｎｍ。在８７３Ｋ左右ＴｉＯ２微粒出现锐钛矿与金红石型混晶结构。     

Electrochemical methods for the preparation of gold-coated TiO2 nanoparticles with variable coverages

We report here the first electrochemical methods to prepare elemental Au0-coated TiO2 nanoparticles with controllable coverages. First, Au substrates were cycled in a deoxygenated aqueous solution containing 0.1 N HCl and 1 mM TiO2 nanoparticles from -0.28 to +1.22 V versus Ag/AgCl at 500 mV/s with different numbers of scans. The durations at the cathodic and anodic vertexes were 10 and 5 s, respectively. After this process, positively charged Au-coated TiO2 nanoparticles were formed in the solutions. Then a cathodic overpotential of 0.6 V from the open circuit potential of ca. 0.82 V versus Ag/AgCl was applied under sonication to synthesize elemental Au0-coated TiO2 nanoparticles. The coverage of Au shells in the elemental Au-coated TiO2 nanoparticles is varied from 10% to 95% by increasing the number of scans from 10 to 50 in preparing the positively charged Au-coated TiO2 nanoparticles. The extremely high coverage of 95% in this study is notable, as compared with other methods to prepare Au-coated TiO2 nanoparticles.     

反胶束体系制备负载型TiO2纳米光催化剂

在AOT/异辛烷反胶束体系中制备了粒径为2～5nm的单分散球形TiO₂纳米粒子,用TEM,DSC和XRD等手段对其进行了分析;用浸渍法以小孔分子筛HZSM-5为载体制备了负载型TiO₂纳米粒子,用FTIR,Langmuir及BET等手段进行了表征;用以上2种TiO₂粒子作光催化剂进行了简单模拟废水处理研究,用UV-Vis光谱分析其催化效果表明,负载型TiO₂纳米粒子比纯TiO₂纳米粒子的光催化活性更高.     

Preparation of highly uniform Ag/TiO2 and Au/TiO2 supported nanoparticle catalysts by photodeposition

Photodeposition of Ag nanoparticles on commercial TiO2 particles and nanoparticles was performed in order to provide direct visualization of the spatial distribution of photoactive sites on sub-micrometer-scale and nanoscale TiO2 particle surfaces and to create materials for potential catalytic applications. HRTEM (high-resolution transmission electron microscopy) and HAADF-STEM (high-angle annular dark-field scanning transmission electron microscopy) were used to characterize these materials. The size and spatial distributions of the Ag nanoparticles on the commercial TiO2 were not uniform; the concentration of Ag was higher on grain boundaries and at the edges of these submicrometer particles. In the case of TiO2 nanoparticles, the size distribution of the Ag nanoparticles deposited was relatively uniform and independent of irradiation time and photon energy. The amount of Ag deposited on TiO2 nanoparticles was at least 6 times higher than that on the commercial samples for comparable irradiation conditions. Compared to the case of Ag photodeposition, the difference in the amount of Au photodeposited on TiO2 particles and nanoparticles was even greater, especially at low precursor concentrations. Photodeposition on TiO2 nanoparticles is suggested as a potential method for the preparation of Au/TiO2 catalysts, as loadings in excess of 10 wt % of uniform 1 nm metal particles were achieved in this work.     

Photokilling cancer cells using highly cell-specific antibody-TiO(2) bioconjugates and electroporation

In this paper, it was reported for the first time that the combination of the electroporation and the conjugation of the TiO(2) nanoparticles with the monoclonal antibody could improve the photokilling selectivity and efficiency of photoexcited TiO(2) on cancer cells in the photodynamic therapy(PDT) because the conjugation of the TiO(2) nanoparticles with monoclonal antibodies could increase the photokilling selectivity of TiO(2) nanoparticles to cancer cells and the electroporation could accelerate the delivery speed of the TiO(2) nanoparticles to cancer cells. It was observed that using this combination method, 100% human LoVo cancer cells were photokilled within 90 min, while only 39% of the normal cells were killed under the irradiation of the ultraviolet (UV) light (365 nm). Furthermore, the combination method may be used to photokill various kinds of caner cells only if the antibody conjugated on the TiO(2) nanoparticles is changed.