新型聚酰胺胺树形分子的合成及表征

聚酰胺胺(Polyamidoamine,PAMAM)树形分子因其具有独特的结构特点,尤其是分子内部的空腔以及大量的表面官能团,在分子识别试剂、催化剂以及生物医用材料等领域有着广泛的应用.树形分子的柔顺性对其在基因转染和药物输送领域的应用有明显影响,而通过增大树形分子的核结构可以有效提高树形分子的柔顺性.通过过量的乙二胺与丙烯酸甲酯反应制备比乙二胺具有更长结构的化合物.以此化合物为核,通过重复的迈克尔加成和酰胺化反应合成1代到4代聚酰胺胺树形分子.运用柱层析分离的方法和乙醚沉降法对产物进行分离提纯,并通过红外光谱和核磁波谱氢谱对其结构进行表征.红外表征结果证实了每步反应的有效性,而核磁谱图表明合成了带有羰基基团的核单元,并在此基础上制得了目标聚酰胺胺树形分子.该系列产物不但具有聚酰胺胺树形分子的结构特点,而且其内部核单元变大并带有酰胺基团.这种核单元在一定程度上增大了树形分子的柔顺性并改变了核结构的亲水性,有望为树形分子在基因转染和药物输送方面的应用研究提供新的方案.     

Self-assembly of Ag-TiO2 nanoparticles: Synthesis, characterization and catalytic application

The formation of Ag clusters on titanium oxide (TiO2) nanoparticles was achieved by self-assembly process and calcination. The obtained nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and ultraviolet visible spectroscopy (UV-Vis), and conventional techniques (XRD, TEM and UV-Vis) were used to identify Ag particles on the TiO2 surfaces. The results show that Ag-TiO2 particles can be applied to improve catalytic activity of the epoxidation of styrene oxides. Styrene oxide is the main product of catalytic reaction with H2O2 as the oxidant by using Ag-TiO2 nanoparticles as catalysts. High catalytic activitity of styrene oxide can be obtainable at 80 ℃. The reaction temperature, reaction time, the molar ratio of H2O2/styrene and solvent affect greatly the catalytic epoxidation of styrene.     

Preparation and Properties of Poly(amidoamine) Dendrimer/Quaternary Ammonium Chitosan Hydrogels

A novel quaternary ammonium chitosan hydrogel modified by poly(amidoamine)(PAMAM) dendrimer was prepared by using glutaraldehyde as a cross-linker. The hydrogel was characterized by Fourier transform infrared spectroscopy(FTIR) and scanning electron microscopy(SEM). The results confirmed its highly porous three-dimensional network structure. The swelling test of hydrogel proved that it had excellent swelling and p H-sensitive properties. The increasing PAMAM content or quaternization degree led to the increase in swelling properties. And the hydrogel with lower cross-linking agent concentration or quaternary ammonium chitosan concentration exhibited better swelling properties. The antibacterial results indicated that with the increase in the PAMAM content, quaternary ammonium chitosan concentration or cross-linking agent concentration, the hydrogels showed better antibacterial activities against both Staphylococcus aureus(S. aureus) and Escherichia coli(E. coli). Thus, the hydrogel could serve as a promising antibacterial material in the future.     

Completely green synthesis of Ag nanoparticles stabilized by soy protein isolate under UV irradiation

A completely green pathway for the preparation of Ag nanoparticles was proposed, by using soy protein isolate (SPI) as stabilizer under UV irradiation and H2O as the environmentally benign solvent throughout the preparation. Transmission electronic microscopy (TEM) and zeta potential characterization results indicated that the Ag nanoparticles were stable and well dispersed with an average diameter about 13 nm, and X-ray diffraction (XRD) analysis of SPI/Ag composite nanoparticles confirmed the formation of metallic silver. UV-Vis spectrum showed that the Ag nanoparticles dispersion solution had the maximum absorbance at about 430 nm due to surface plasmon resonance of the Ag nanoparticles. Infrared spectroscopy confirmed that the polypeptide backbone of SPI was not cleaved during the conjugation process and that some active amino groups were oxidized. The SPI/Ag composite nanoparticles have excellent antibacterial activity against two representative bacteria, staphylococcus aureus (Gram positive) and escherichia coli (Gram negative) in the presence of SPI.     

Photorefraetive Effect in a CdS Nanoparticles- sensitized Polymer Composite

The photorefractive （PR） performance of an organic/inorganic hybrid polymer composite sensitized by CdS nanoparticles, combining poly（N-vinylcarbazole） （PVK）, the second-order optically nonlinear chromophore 1-n-butoxy-2-methyl-（4-p-nitropheylazo）benzene （BMNPAB） and 9-ethylcarbazole （ECZ） was studied. It was confirmed that the CdS colloidal particles had a nanoscale size and quantum confinement effect adopting transmission electron microscopy and UV-Vis absorption spectroscopy. The addition of CdS nanoparticles as a photosensitizer in PVK will be significant enhancement of photoconductivity because of the high photocharge generation quantum efficiency and high charge transport to conducting polymer. The polymer composite film exhibited PR effect with a method of two-beam coupling experiment. And an asymmetric two. beam coupling gain of 45.8 cm^-1 without applied electric filed is obtained at 632.8 nm wavelength.     

PAMAM树形分子影响CaCO3结晶的机理研究

研究了不同端基的聚酰胺胺(PAMAM)树形分子以及CH3COONa,PAANa对CaCO3在水溶液中结晶的影响,分析了PAMAM树形分子影响CaCO3结晶体机理.研究表明,含-COONa端基的PA-MAM树形分子在CaCO3的结晶过程中与Ca2 发生络合,形成由Ca-O键连接的络合物,Ca2 在进入晶格时由于受到树形分子空间位阻的作用只能按照霰石的形式进行排列.含-COONa端基的PAMAM树形分子起到了晶体改性剂和结晶抑制剂的作用.     

磁性Fe⁃Au复合材料的制备及SERS性能

表面增强拉曼散射光谱(SERS)是一种广泛应用于低浓度分子物种识别并且能够提供结构信息的技术。SERS检测中基底纳米材料的颗粒大小、形状和空间分布对检测结果有着重要影响。探索制备新型纳米结构可以为SERS研究和应用提供新的活性基底和理论基础。由于具有良好的传质和吸附性能,多孔材料广泛应用于构筑SERS活性基底纳米复合物。以多孔磁性纳米材料作固相载体,通过水热合成多孔纳米α⁃Fe2O3,再将其还原成Fe,使Fe的表面也有孔道存在。在Fe表面自组装Au纳米材料构筑SERS基底,以对巯基苯胺（PATP）和三聚氰胺水溶液作为目标分子,对其SERS性能进行测试。调控Au纳米粒子尺寸大小,考察其对SERS性能影响,得到50 nm Au具有最优性能。利用扫描电子显微镜（SEM）、X 射线衍射(XRD)和N2吸附等表征手段,对纳米复合物结构及组成进行分析表征。结果表明,得到了一种同时具有吸附和检测效果的纳米复合物SERS基底。     

Effect of Sequential Ions Implantation on Structure of Cu, Ag Nanoparticles

The preparation of metal nanoparticles composites by Cu, Ag ions sequential implantation is studied. The formation of Cu, Ag nanoparticles has been evidenced by grazing incidence X-ray diffraction, extended x-ray absorption fine structure and transmission electron microscopy. With the increase of Ag ion implantation dose, the size and density of Ag nanoparticles increase significantly.     

Analysis on the characteristic properties of PEDOT nano-particle based on reversed micelle method

Based on the study of a new type of conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT),we focussed on the preparation and characteristics of PEDOT nanoparticles made by reversed micelle method.Moreover,we deeply investigated the optical,electrical and the thermal stability of PEDOT nanoparticles.The main results are as follows: the small-sized PEDOT nanoparticles were prepared and utilized by different methods,such as ultraviolet/visible (UV-Vis) spectroscopy,Fourier-transform infrared (FT- IR) spectrum,scanning electron microscopy(SEM) and so on.The results show that the amount of oxidizer,ultrasonic treatment,polymerizing temperature and doping degree can influent morphology,electrical ability and gas sensitivity of PEDOT nanoparticles.The Bragg peaks of nanoparticles at 6.7°,12.7°,25° were observed by XRD and the better orientation of molecular chain was attributed to the effective doping of toluene-p-sulfonic acid,which also resulted in an enhancement of thermal stability of nanoparticles than conventional PEDOT.     

Ag/TiO2纳米粒子的制备与表征

为了扩大纳米TiO_2在可见光范围的吸收,进行在纳米TiO_2中掺入Ag实验.以工业级偏钛酸、硝酸银为主要实验原料,采用一种简易的方法制备出Ag/TiO_2纳米粒子,并通过X线衍射(XRD)、扫描电子显微镜(SEM)、透射电镜(TEM)、X射线光电子能谱(XPS)、紫外一可见光吸收光谱(UV-vis)对该粒子进行表征.结果表明,二氧化钛以锐钛型晶型,银以单质的形式存在于纳米复合粒子中;Ag的结合能367.476 eV(3d_(3/2))与373.453 eV(3d_(5/2))分别比纯银的结合能368.4 eV(3d_(3/2))与374.4 eV(3d_(5/2))低,这是由于制备Ag/TiO_2时煅烧温度较纯银高,银簇生长较大引起的;并显示复合粒子的粒径约为30 nm;Ag/TiO_2纳米粒子感应波长明显红移,增强了纳米TiO_2在可见光范围内的吸收.     

Ag修饰La0.8Sr0.2CoO3空气电极电催化性能

采用溶胶-凝胶法合成了钙钛矿型La0.8Sr0.2CoO3复合氧化物,并选用Ag对其进行修饰,获得Ag/La0.8Sr0.2CoO3纳米粉体,利用XRD、XPS方法对催化剂的结构与组成进行表征;然后将该粉体作为催化材料制备出空气电极,在碱性介质中,通过测量空气电极的稳态极化曲线和交流阻抗谱,考察Ag含量对催化剂的电催化活性的影响.研究发现,Ag的加入增强了La0.8Sr0.2CoO3复合氧化物的导电性,并对电极材料的催化活性起到一定的促进作用;当Ag的质量分数为8%时,Ag/La0.8Sr0.2CoO3氧化物电极材料催化活性较高.     

一锅法制备聚乙烯醇载银海绵及其催化性能

以水为溶剂、以聚乙烯醇（PVA）为还原剂和纳米银的载体,通过一锅法制备了一种聚乙烯醇载银（PVA/Ag）海绵并将其用于催化还原对硝基苯酚（4-NP）。采用扫描电子显微镜、傅里叶变换红外光谱、拉曼光谱、X射线衍射、热重分析分别表征了PVA/Ag海绵的形貌、组成与结构,并用紫外-可见光谱分析了其催化还原4-NP的性能。结果表明:一锅法制备的PVA/Ag海绵具有三维多孔结构,有效地抑制了纳米银颗粒的团聚,使得纳米银颗粒分布均匀,在4-NP还原中具有良好的催化性能。当4-NP的浓度为0.2 mmol/L时,载银量为2.2%的PVA/Ag海绵在14 min内完成催化,催化效率达到98%以上。因此,本文制得的PVA/Ag海绵具有制备简单、催化效率高等特点,在污水处理领域具有潜在应用前景。     

An optical investigation of silver nanoclusters composite soda-lime glass formed by electric field assisted diffusion

Silver nanoclusters (NCs) embedded in soda-lime glass was synthesized by the electric fieldassisted diffusion (EFAD) and successive annealing. The samples were characterized by UV-Vis absorption spectroscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy (XPS), and lifetime measurements. The experimental results show that the growth of silver clusters is favored by the annealing temperature and dwell time. The as-diffused and annealed glass samples show photoluminescence around 550 nm under UV excitation, which can be associated with the presence of L-center and Ag₃ ⁺ cluster. And the increasing of the annealing temperature and dwell time results in an appearance of the SPR peak and the decreasing of the luminescence intensities because the Ag₃ ⁺ clusters grow up into the Ag nanoparticles.     

Preparation,Swelling and Antibacterial Behaviors of N-Succinyl Chitosan-g-Poly(Acrylic Acid-co-Acrylamide) Superabsorbent Hydrogels

Superabsorbent hydrogels were prepared successfully from N-succinyl chitosan grafted poly(acrylic acid-co-acrylamide). The potassium persulfate(KPS), N, N'-methylenebisacrylamide(MBA) were used as the initiator and crosslinker, respectively. Fourier transform infrared spectroscopy(FTIR) and scanning electron microscopy(SEM) were used to confirm the porous network structure of superabsorbent hydrogel. The effects of reaction parameters on the swelling behaviors of the superabsorbent hydrogels were investigated. The results indicated that water absorbency increased first, and then decreased gradually with the increase in the contents of monomer(AA+AM), KPS, MBA or acrylamide. The product had excellent water absorbency of 1375 g/g in distilled water and 83 g/g in 0.9wt% NaCl solution. Simultaneously, the superabsorbent hydrogels were p H sensitive. The antibacterial activities of the hydrogels against Escherichia coli(E. coli) were improved effectively because of polyamidoamine(PAMAM) dendrimer absorbed in the hydrogels.     

Composite nanofiltration membranes synthesized from PAMAM and TMC by interfacial polymerization

A novel NF membrane prepared with poly(amidoamine) (PAMAM) dendrimer and trimesoyl chloride (TMC) by interfacial polymerization on polysulfone (PSF) ultrafiltration membrane was investigated. Field emission scanning electron microcopy (FESEM) ,atomic force micrograph(AFM) and contact angle(CA) of pure water on PA and PSF substrate were employed to characterize the chemical and physical properties of membranes. The PAMAM concentration,retention of salt solutions and organics were studied on the performance of the NF membrane. From the analyses of SEM and AFM,the polyamide active skin layers of the composite membranes are dense,rough,and finely dispersed nodular structures,packed tightly by the spherical globules. The contact angle of PA nanofitration membrane decreased after polymerization. The higher PAMAM concentration can result in lower flux and higher rejection. The salt rejection of PA membranes decreases in the order K2SO4 > Na2SO4 > MgSO4 > MgCl2 > CaCl2 > NaCl,which indicates that the resulting membranes is nagatively charged. The pH increases from 3 to 10 in the feed resulting in the decrease of the flux and the increase of the rejection for Na2SO4 solution. The molecular weight cut off (MWCO) of the composite NF membrane is nearly 860 kg/mol. The resulted PA membrane can be used to separate small organics and salt solutions.     

聚吡咯－银纳米复合材料的制备及电化学性能研究

采用化学氧化法,以十二烷基硫酸钠为掺杂剂,以FeCl3为氧化剂,在0℃～3℃引发吡咯单体氧化聚合,制备聚吡咯（PPy）纳米颗粒。利用化学还原法制备Ag溶胶。将PPy与Ag溶胶复合,制备PPy-Ag纳米复合材料。利用FESEM,TEM,XPS和XRD对PPy—Ag复合材料进行表征。利用电化学方法研究PPy-Ag纳米复合材料对甲醇的催化反应。结果表明,PPy—Ag对甲醇具有较高的电催化活性。     

紫外辐照法制备Ag纳米颗粒用于石墨烯表面缺陷的标记与修复

为了标记化学法制备石墨烯时引入的缺陷,采用紫外辐照的方法,利用Ag颗粒与含氧官能团之间的相互作用实现了对缺陷的定量标记.结果表明该方法能提供石墨烯表面缺陷的数量和分布信息.另外Ag纳米颗粒对石墨烯缺陷有修复作用,有利于提高石墨烯的导电能力.     

银模板刻蚀参数对玻璃光学和润湿性能的影响

用直流溅射技术及后续高温退火处理,在玻璃表面制备Ag纳米粒子掩膜板,通过控制不同的退火温度和腐蚀时间,研究玻璃表面透过率及润湿性的变化.采用扫描电子显微镜(SEM)观测了Ag纳米粒子的大小和分布.采用UV-Vis分光光度计测定刻蚀后玻璃的透过率变化,采用表面接触角仪测定了刻蚀后玻璃表面润湿性的改变,以及有机氟硅烷处理后表面润湿性的改变.结果表明:退火温度为300℃时,表面Ag纳米粒子更均匀;刻蚀时间为4 min时,可见光透过率提高最多,最高可达93.8%,比原始样品提高了3.8%;刻蚀后玻璃的亲水性更加明显,接触角为9°,后续经过化学修饰后玻璃表面的疏水性有所提高,但提高并不明显,表面接触角为102°.     

Synthesis of novel CaCO_3/Ag_2CO_3/Ag I/Ag plasmonic photocatalyst with enhanced visible light photocatalytic activity.

In this work, novel Ca CO3/Ag2CO3/Ag I/Ag plasmonic photocatalysts were successfully synthesized by a two-step in situ ion exchange process and their photocatalytic properties were studied. The morphology, crystal structure and optical properties of the as-prepared Ca CO3/Ag2CO3/Ag I/Ag nanocomposites were characterized by transmission electron microscopy(TEM), XRay diffraction(XRD), and UV-vis diffuse reflectance spectroscopy. The photocatalytic activity of the obtained nanocomposites was evaluated by the photodegradation of methyl orange(MO) under visible light irradiation. It was found that the as-prepared Ca CO3/Ag2CO3/Ag I/Ag plasmonic photocatalyst exhibits high visible light photocatalytic activity. With an optimized composition, MO dye can be decomposed by more than 94% within 15 min under visible light irradiation. Moreover, the photocatalytic stability could be greatly improved upon the addition of Na2CO3 into the photocatalytic system. From the proposed photocatalytic mechanism, the strong surface plasmon resonance effect of Ag nanoparticles and the efficient separation of photogenerated electrons and holes can effectively enhance the photocatalytic performance of the Ca CO3/Ag2CO3/ Ag I/Ag composites.     

Immobilization of metalloporphyrins on CeO_2@SiO_2 with a core-shell structure prepared via microemulsion method for catalytic oxidation of ethylbenzene

Ce O2@Si O2 core-shell nanoparticles were prepared by microemulsion method, and metalloporphyrins were immobilized on the Ce O2@Si O2 core-shell nanoparticles surface via amide bond. The supported metalloporphyrin catalysts were characterized by N2 adsorption-desorption isotherm(BET), scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), ultraviolet and visible spectroscopy(UV-Vis), and Fourier transform infrared spectroscopy(FT-IR). The results show that the morphology of Ce O2@Si O2 nanoparticles is core-shell microspheres with about 30 nm in diameter, and metalloporphyrins are immobilized on the Ce O2@Si O2 core-shell nanoparticles via amide bond. Especially, the core-shell structure contains multi Ce O2 core and thin Si O2 shell, which may benefit the synergistic effect between the Ce O2 core and the porphyrin anchored on the very thin Si O2 shell. As a result, this supported metalloporphyrin catalysts present comparably high catalytic activity and stability for oxidation of ethylbenzene with molecular oxygen, namely, ethylbenzene conversion remains around 12% with identical selectivity of about 80% for acetophenone even after six-times reuse of the catalyst.