一种Q态纳米CdS的新型制备法——聚合物分散法

采用一种Q态CdS的新型制备法——聚合物分散法, 即用水溶性聚合物溶液作为分散剂, 用2-巯基乙醇(或十二硫醇)作表面修饰剂, 在聚合物网络中构筑出四种粒径的、单分散性的Q-CdS. 通过UV-Vis光谱和TEM考察了Q-CdS的粒径及分布情况, 并用FL光谱研究了不同尺寸的Q-CdS的荧光性能. 结果表明, 采用聚合物分散法可以方便、快捷地得到粒径小且分布窄的Q-CdS纳米粒子, 这些粒子在紫外光谱及荧光光谱上均表现出明显的量子尺寸效应.     

原位聚合法制备聚合物/纳米SiO_2复合材料的研究进展

纳米SiO_2改性聚合物制备的关键在于提高纳米粒子与聚合物基体的相容性及分散性;对纳米SiO_2进行不同的表面改性及选择合适的复合材料制备方法可以改变纳米粒子与聚合物基体的界面结合方式以及相容性和分散性,进而在不同程度上影响材料的性能.本文介绍了改性前后纳米SiO_2与聚合物基体的多种界面结合方式,对近年来利用原位聚合法制备聚合物/纳米SiO_2复合材料的研究现状和进展进行了综述.     

磺化聚芳醚酮砜/ZrO2复合型质子交换膜的制备与性能

通过溶胶-凝胶法制备了纳米ZrO2无机粒子,再通过溶胶共混法制备了不同ZrO2含量的磺化聚芳醚酮砜(SPAEKS)复合膜,红外光谱显示复合膜中存在Zr-O-Zr吸收峰,扫描电镜照片显示纳米ZrO2无机粒子能够均匀地分散在SPAEKS聚合物基体中,未发生团聚现象.通过对复合膜的性能测试发现,纳米ZrO2无机粒子的引入提高...     

聚苯胺对纳米CdS的光致发光增强效应

利用电化学脉冲沉积法在聚苯胺(PANI)膜上制备了纳米CdS/PANI复合膜,并利用扫描电镜光谱、紫外可见光谱、红外光谱、拉曼和荧光等光谱技术表征复合膜的形貌、结构及性质.CdS/PANI复合膜中CdS微粒呈现量子尺寸效应;CdS和PANI间存在相互作用;由于聚苯胺和CdS能级的合适匹配,聚苯胺对CdS的光致发光(PL)有增强效应,增强机理为光生载流子的传递机理.     

壳聚糖-CdS复合膜制备及其对吡啶的传感特性

利用壳聚糖（CS）易于成膜的特点，模拟生物矿化，在有机物调制下通过异相成核生长制备了CS/CdS纳米颗粒复合膜.研究了成膜条件对膜的水热稳定性和发光性能的影响，以及CS/CdS纳米颗粒复合膜对水体中吡啶的响应特性.扫描电镜分析表明CS/CdS纳米颗粒复合膜均匀性好， CdS以物理掺杂方式均匀分布于CS薄膜中， CdS颗粒尺寸在70 nm左右.但薄膜荧光光谱位置和形状表明实际发光的CdS簇集体直径小于20 nm.由此推测电镜观察到的CdS颗粒可能是由许多CdS小颗粒聚集而成，小颗粒之间因有机物的存在而相互隔离. CS/CdS纳米颗粒复合膜的荧光发射对水体中吡啶的存在十分敏感，微量吡啶的存在会引起薄膜荧光发射急剧增强.除铜和碘离子外，水体系中其他常见离子对薄膜荧光发射没有显著影响，预期CS/CdS纳米颗粒复合薄膜有可能发展成为一种重要的水体系吡啶测定专用传感薄膜材料.     

树状大分子保护的CdS纳米粒子的合成与表征

以聚酰胺-胺型树状大分子（PAMAM）为保护剂,在水溶液中制备了不同粒径的CdS纳米粒子,分别考察了PAMAM的代数以及保护剂与CdS物质的量比对CdS纳米粒子大小及荧光性能的影响.利用紫外-可见光谱、荧光光谱、透射电子显微镜对其光学性能和结构进行了表征.     

ITO/TiO2表面电沉积CdS纳米粒子及其薄膜的光电性能

采用阴极恒电位沉积方法, 在TiO2表面沉积制备出CdS纳米粒子. XRD和SEM测试结果表明, CdS粒子的结构以六方晶相为主, 粒径分布均匀, 表面形貌呈菜花状. 通过调节沉积电位和沉积时间等因素在一定程度上可以控制CdS纳米粒子的生长. 随着沉积电位变负, CdS粒子的粒径逐渐减小. 沉积时间越短, 粒子粒径越小. 紫外-可见吸收光谱测试结果表明, 不同条件下制备出来的CdS粒子表现出一定的量子尺寸效应. 此外, 沉积条件也会影响ITO/TiO2/CdS复合半导体薄膜的光电性能.     

CdS纳米粒子与半胱氨酸相互作用的研究

合成了粒径均匀和分散性好的CdS纳米粒子.通过改变CdS纳米粒子及半胱氨酸的浓度、体系的pH值及CdCl2和CH3CSNH2摩尔比等实验条件跟踪监测了CdS纳米粒子光谱性质的变化,探讨了CdS纳米粒子与半胱氨酸之间的相互作用及化学反应机理.     

超顺磁/荧光双功能纳米粒子的合成、表征和生物功能化

通过反相微乳液聚合, 在热解法合成的MnFe2O4纳米粒子表面修饰了一层掺杂有荧光染料(联吡啶钌)的SiO2, 制备了同时具有超顺磁性和荧光特性的双功能纳米粒子. 再通过氨基硅烷的修饰作用, 将该双功能纳米粒子与万古霉素结合, 所得到的生物功能化的纳米粒子表现出很好的对大肠杆菌的识别和磁性分离能力. 本研究制备的超顺磁/荧光双功能纳米粒子具有磁性强、光稳定性高、制备简单、分散性好和尺寸均匀等优点, 可以推断这种新型纳米粒子在生物学、医学和分析化学等领域中将有广阔的应用前景.     

Q态硫化镉纳米晶的制备、形态、量子尺寸效应与光催化性能

分别引入辛基硫醇作配体, 十六烷基三甲基溴化铵(或四丁基溴化铵)作有机正离子合成CdS纳米簇合物. 采用后沉淀分离技术, 分别制备得到粒度分布窄、粒径2~5 nm的Q态CdS纳米晶粒. 用紫外吸收光谱、透射电子显微镜、小角X射线衍射来测定粒径的大小. 在紫外光谱、荧光光谱和X射线衍射上, 表现出明显的量子尺寸效应. 当粒径大到一定程度(大于10 nm)时, 量子尺寸效应就不明显. 用ESR研究Q态纳米粒子的光催化性能, 结果表明加入纳米硫化镉颗粒可明显促使甲醇、乙醇发生光催化反应, 释放出CH3-·CHOH(对乙醇体系)或·CH2OH(对甲醇体系), 在有机合成上有着重要的应用价值.     

表面修饰的Q态纳米CdS的荧光性能研究

以硫醇为表面修饰剂,通过控制硫醇与Cd²⁺的比例,得到性能稳定的Q-CdS,而后将Q-CdS与聚合物通过共混复合成膜.通过荧光光谱研究了硫醇和聚合物对Q-CdS的表面修饰作用,研究发现硫醇的长碳链有效阻止了CdS粒子间的团聚,碳链的增加导致Q-CdS稳定性的增强,Q-CdS的激子发射峰强度增大,且这种表面修饰效应随硫醇加入量的增大而增强,在一定硫醇加入量时的激子荧光发射强度达到最大.由于介电局域效应,聚合物的加入使Q-CdS的表面态荧光发光强度呈数量级增大.另一方面,随着聚合物加入量的增加又会导致Q-CdS的表面钝化,缺陷减小,表面态荧光发射峰相对减弱,而激子发射峰却增强.     

Spectroscopic and Discharge Studies on Graphene Oxide Doped PVA/PVP Blend Nanocomposite Polymer Films

Graphene oxide (GO) nanoparticles were synthesized by modified Hummers method. The synthesized GO nanoparticles were incorporated in polyvinyl alcohol/polyvinyl pyrrolidone (PVA/PVP) blend polymers for the preparation of nanocomposite polymer films by solution cast technique. Different characterizations such as XRD, UV–Vis and FTIR were carried-out on to the prepared nanocomposite polymer films. The thermal analysis of the films was studied by DSC. The morphology of PVA/PVP:GO polymer films confirms GO was exfoliated within the PVA/PVP matrix and also reveals the heterogeneous phase of nanocomposite polymer electrolyte systems. From the conductivity studies the highest conductivity of PVA/PVP: GO (0.45: 0.3) was found to be 8.05 × 10^–4 S/cm at room temperature. Solid state battery has been fabricated with the configuration of Mg⁺/(PVA/PVP:GO)/(I₂ + C + electrolyte) and its cell parameters were calculated for a constant load of 100 kΩ.     

Radiolytic synthesis and characterization of Ag-PVA nanocomposites

The Ag-PVA nanocomposites with different contents of inorganic phase were prepared by reduction of Ag⁺ ions in aqueous PVA solution by gamma irradiation followed by solvent evaporation. Optical properties of the colloidal solutions and the nanocomposite films were investigated using UV-vis spectroscopy. Structural characterization of the Ag nanoparticles was performed by TEM and XRD. Interaction of the Ag nanoparticles with polymer matrix and the heat resistance of the nanocomposites were followed by IR spectroscopy and DSC analysis. IR spectra indicated that Ag nanofiller interact with PVA chain over OH groups. The changes of heat resistance upon the increase of the content of inorganic phase are correlated to the adsorption of polymer chains on the surface of Ag nanoparticles.     

Preparation and characterization of poly(l-lactic acid)/TiO2 nanoparticle nanocomposite films with high transparency and efficient photodegradability

Poly(l-lactic acid)-TiO₂ nanoparticle nanocomposite films were prepared by incorporating surface modified TiO₂ nanoparticles into polymer matrices. In the process of preparing the nanocomposite films, severe aggregation of TiO₂ nanoparticles could be reduced by surface modification by using carboxylic acid and long-chain alkyl amine. As a result, the nanocomposite films with high transparency, similar to pure PLA films, were obtained without depending on the amount of added TiO₂ nanoparticles. A TEM micrograph of the nanocomposite films suggests that the TiO₂ nanoparticles of 3-6 nm in diameter were uniformly dispersed in polymer matrices. Photodegradation of PLA-TiO₂ nanoparticle nanocomposite films was also investigated. The results showed that nanocomposite films could be efficiently photodegraded by UV irradiation in comparison with pure PLA.     

Study on luminescence characteristic of the ZnO/polymer hybrid films

The cyclohexane solution of PS (polystyrene) and the ethyl acetate solution of PMMA (polymethyl methacrylate) were used as flowing liquid; the ZnO/polymer hybrid colloids were successively produced by focused pulsed laser ablation of ZnO target in interface of solid and flowing liquid. As solvent in the hybrid colloids has volatized, the ZnO/polymer hybrid films were obtained. The hybrid colloids were characterized by high-resolution transmission electron microscopy (HRTEM) and select-area electron diffraction (SEAD). The results show a good dispersion of the ZnO nanoparticles in the polymer matrix. The hybrid films were characterized by fluorescence spectrum, Fourier transform infrared spectroscopy (FTIR) spectroscopy, thermogravimetry with FTIR (TG/FTIR), and X-ray photoelectron spectrum. The results show the ZnO/polymer hybrid films can radiate strong blue light under ultraviolet. Meanwhile, the ZnO/polymer hybrid films have higher chemical stability than ZnO nanoparticles because nano-ZnO nanoparticles were enwrapped by polymers. In addition, the ZnO hybrid films have higher thermal stability then the related pure polymers because of strong interaction among ZnO nanoparticles and polymers.     

Polymer Zwitterions for Stabilization of CsPbBr3 Perovskite Nanoparticles and Nanocomposite Films

Functional polymers with sulfobetaine or phosphorylcholine zwitterions as pendent groups are demonstrated as both ligands and host matrices for CsPbBr₃ perovskite nanoparticles (PNPs). These polymers produce nanocomposite films with excellent NP dispersion, optical transparency, and impressive resistance to NP degradation upon exposure to water. Multidentate interactions of the zwitterion‐containing copolymers with the PNPs induce dispersed or weakly aggregated nanocomposite morphologies, depending on the extent of zwitterionic functionality in the polymer. Incorporating additional functionality into the polymers, such as benzophenone pendent groups, yields lithographically patternable films, while time‐resolved photoluminescence measurements provide insight into the electronic impact of PNPs in zwitterionic polymer matrices.     

Morphology study of gold-chitosan nanocomposites

Gold nanoparticles were prepared in the presence of chitosan via reduction of HAuCl4 with sodium borohydride. The gold-chitosan nanocomposite was formed by adsorbing chitosan molecules onto the gold nanoparticle surfaces. The resulting gold nanoparticles were characterized by transmission electron microscopy and UV-vis spectroscopy. Morphology of gold-chitosan nanocomposite films was investigated by polarized optical microscopy. The morphology of chitosan crystal cast from the prepared nanocomposite was much different from that cast from chitosan solution due to the possible nucleation of gold nanoparticles. A branched-like structure or a cross-linked needle-like structure could be formed in nanocomposite films with different casting volumes.     

Synthesis of polytetrafluoroethylene/polyacrylate core-shell nanoparticles via emulsifier-free seeded emulsion polymerization

Polytetrafluoroethylene (PTFE)/polyacrylate core-shell nanoparticles were produced via the emulsifier-free seeded emulsion polymerization of acrylate monomers with PTFE latex as seed. The monomer conversions under different synthesis parameters were monitored by a gravimetric method. The polymerization conditions for preparing PTFE/polyacrylate core-shell nanoparticles were surveyed and optimized. The chemical component of the PTFE/polyacrylate particles was confirmed by comparing the Fourier-transform infrared spectra of PTFE and PTFE/polyacrylate particles. The core-shell structure of the resulting PTFE/polyacrylate nanocomposite particles was investigated by transmission electron microscopy. The water contact angles of the films prepared from PTFE/polyacrylate nanocomposite particles showed that the films were hydrophilic, which confirmed that polyacrylate covered the surface of the PTFE particles. This kind of PTFE/polyacrylate core-shell nanoparticles might advance the compatibility of PTFE with other materials due to the covering of the polyacrylate shell on the surface of PTFE, which would make them promising in various fields.     

Preparation and characterization of polymer/silica nanocomposites via double in situ miniemulsion polymerization

Polymer/SiO₂ nanocomposite microspheres were prepared by double in situ miniemulsion polymerization in the presence of methyl methacrylate, butyl acrylate, γ‐methacryloxy(propyl) trimethoxysilane, and tetraethoxysilane (TEOS). By taking full advantage of phase separation between the growing polymer particles and TEOS, inorganic/polymer microspheres were fabricated successfully in a one‐step process with the formation of SiO₂ particles and the polymerization of organic monomers taking place simultaneously. The morphology of nanocomposite microspheres and the microstructure, mechanical properties, thermal properties, and optical properties of the nanocomposite films were characterized and discussed. The results showed that hybrid microspheres had a raspberry‐like structure with silica nanoparticles on the shells of polymer. The silica particles of about 20 nm were highly dispersed within the nanocomposite films without aggregations. The transmittance of nanocomposite film was comparable to that of the copolymer film at around 70–80% from 400 to 800 nm. The mechanical properties and the fire‐retardant behavior of the polymer matrix were improved by the incorporation of silica nanoparticles. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3128–3134, 2010