多功能NiFeAu纳米粒子的合成与表征

采用一罐纳米乳液法,以聚乙二醇-聚丙二醇-聚乙二醇(PEO-PPO-PEO)三嵌段共聚物为表面活性剂,通过还原前驱体乙酰丙酮镍、乙酰丙酮铁(Ⅱ)和醋酸金,成功制备了NiFeAu纳米粒子.采用透射电镜和X射线衍射仪分析了NiFeAu纳米粒子的形貌和结构;采用傅立叶变换红外光谱仪分析了三嵌段共聚物在NiFeAu纳米颗粒表面的覆盖情况;采用紫外-可见吸收光谱仪和振动样品磁强计测试了纳米粒子的光学和磁学特性.结果表明,三嵌段共聚物成功地结合于NiFeAu纳米颗粒表面;所制备的纳米粒子粒径分布较窄、结晶性能良好,并兼具光学和磁学特性.     

高斯方程对CoFe_2O_4纳米复合颗粒的粒径分布分析

采用Polyol合成法,以1,2—十六烷二醇为还原剂,乙酰丙酮钴(Ⅱ)和乙酰丙酮铁(Ⅱ)为前驱体,以三嵌段共聚物PEO-PPO-PEO为表面活性剂成功合成了PEO-PPO-PEO包裹的CoFe_2O_4纳米复合颗粒.通过透射电子显微镜(TEM)和X射线衍射(XRD)对其微观形貌、尺寸大小、粒径分布和纳米结构进行了研究.高斯拟合表明CoFe_2O_4纳米颗粒的粒径分布呈双峰分布的正态分布曲线.粒径的双峰分布预期为纳米复合颗粒带来新的性质.     

修正的Langevin函数对CoFe_2O_4纳米复合颗粒磁滞回线的拟合

通过振动样品磁强计(VSM)对采用Polyol合成法,以三嵌段共聚物PEO-PPO-PEO为表面活性剂,1,2—十六烷二醇为还原剂,乙酰丙酮钴(Ⅱ)和乙酰丙酮铁(Ⅱ)为前驱体合成的CoFe_2O_4纳米复合颗粒的磁性能进行测试,结果表明所制得的CoFe_2O_4纳米复合颗粒在室温下显示软铁磁性,矫顽力约为96 Oe.采用修正的Langevin函数对CoFe_2O_4纳米复合颗粒的磁滞回线进行拟合,分析结果预示CoFe_2O_4纳米复合颗粒由两个磁性相组成.对磁滞回线进行分析有助于深入了解纳米复合颗粒的磁性能.     

以Pluronics~为第二组分制备聚乳酸蜂窝状规整多孔薄膜

以聚乳酸(PLA)为成膜材料,以两亲三嵌段共聚物PEO-PPO-PEO(Pluronics)为第二组分,利用水辅助法成功地制备了聚乳酸蜂窝状多孔膜.研究了环境湿度、溶液浓度和所用PLA分子量对多孔膜结构的影响.结果表明,加入第二组分PEO-PPO-PEO能有效地促进规整蜂窝结构的形成.蛋白质吸附实验结果进一步证明了PEO-PPO-PEO组分在孔洞内壁的富集,由此构建了阻抗蛋白质吸附的图案化功能结构表面.     

疏水上转换纳米晶的均相体系聚合物包覆及在发光检测中的应用

选用水解的十八碳烯-马来酸酐共聚物(PMAO)为表面修饰分子,发展了一种以疏水纳米粒子吸附表面活性剂十二烷基磺酸钠(Na YF_4-SDS)为中间体的均一液相聚合物包覆纳米粒子方法.该方法解决了油溶性纳米晶与弱极性聚合物分子难以在单一体系下均匀分散的问题,实现了在均一液相体系下对疏水纳米晶的单分散包覆以及表面羧酸官能团修饰.红外光谱与表面Zeta电位测试结果表明纳米晶已被聚合物包覆,粒子表面为强电负性的羧酸基团.电镜结果表明聚合物包覆的上转换纳米晶粒径无明显的变化,具有良好的单分散性.发射光谱表明聚合物包覆前后粒子的发射谱带无显著变化,保持了原油相粒子的发光性能.进一步的特异性识别荧光显微成像实验证实聚合物包覆后的粒子(Na YF_4-PMAO)可用于生物学检测.     

以Pluronics(R)为第二组分制备聚乳酸蜂窝状规整多孔薄膜

以聚乳酸(PLA)为成膜材料, 以两亲三嵌段共聚物PEO-PPO-PEO(Pluronics(R))为第二组分, 利用水辅助法成功地制备了聚乳酸蜂窝状多孔膜. 研究了环境湿度、溶液浓度和所用PLA分子量对多孔膜结构的影响. 结果表明, 加入第二组分PEO-PPO-PEO能有效地促进规整蜂窝结构的形成. 蛋白质吸附实验结果进一步证明了PEO-PPO-PEO组分在孔洞内壁的富集, 由此构建了阻抗蛋白质吸附的图案化功能结构表面.     

氧化铁磁性纳米粒子的表面配体交换及相转移

以苯甲醇为单一溶剂, 通过常压、高温热解乙酰丙酮铁, 制备了尺寸单分散的四氧化三铁磁性纳米粒子. 采用透射电镜(TEM), X射线衍射(XRD), 动态光散射(DLS)等方法对粒子形貌和结构进行了表征. 利用傅里叶变换红外(FT-IR)光谱和热重分析(TGA)研究了所制备纳米粒子的表面化学, 结果表明稳定四氧化三铁粒子的是苯甲酸分子, 且表面覆盖度小于20%. 所制备的磁性纳米粒子可以在室温下方便地进行表面配体交换, 从而为氧化铁磁性纳米粒子的功能化提供新的途径.     

微波辐射无皂乳液聚合制备荧光乳液纳米粒子及其性能研究

以苯乙烯(St)为主要单体,对苯乙烯磺酸钠(NaSS)和可聚合稀土荧光配合物(Eu(AA)(BA)_2Phen)为功能性单体,通过微波辐射无皂乳液聚合制备了Poly(St-NaSS-Eu(AA)(BA)_2Phen)共聚物荧光乳液纳米粒子.利用红外光谱对共聚物的结构进行了证实;通过透射电子显微镜和扫描电子显微镜观察了粒子的形态、结构及大小;利用激光光散射粒度仪测试了粒子的大小及分布;结果发现所制备的共聚物荧光乳液纳米粒子呈大小均一的球形形状,粒径大小约为35 nm;采用荧光分光光度计测试,发现共聚物纳米粒子在595 nm和619 nm处出现Eu~(3+)的特征发射光谱,具有良好的荧光效果.     

嵌段共聚物调控纳米粒子自组装的研究进展

嵌段共聚物和纳米粒子复合纳米材料具有优异的性能,在生物医药、光电材料、催化材料等领域具有很大的应用价值,已成为备受关注的研究热点.利用嵌段共聚物自组装能够形成特定形态的纳米结构聚集体,将纳米粒子选择性的分布和定位于嵌段共聚物聚集体中,可以改善纳米粒子的性能及其应用.本文综述了近年来实验上利用自组装制备嵌段共聚物-纳米粒子复合纳米材料的方法,并总结分析了影响纳米粒子在嵌段共聚物聚集体中的分布和定位的各种因素,包括纳米粒子的大小、形状及其表面化学.最后总结了嵌段共聚物-纳米粒子的自组装在理论模拟方面的研究.     

以Pluronics为第二组分制备聚乳酸蜂窝状规整多孔薄膜

以聚乳酸（PLA）为成膜材料,以两亲三嵌段共聚物PEO-PPO-PEO（Pluronics）为第二组分,利用水辅助法成功地制备了聚乳酸蜂窝状多孔膜.研究了环境湿度、溶液浓度和所用PLA分子量对多孔膜结构的影响.结果表明,加入第二组分PEO-PPO-PEO能有效地促进规整蜂窝结构的形成.蛋白质吸附实验结果进一步证明了PEO-PPO-PEO组分在孔洞内壁的富集,由此构建了阻抗蛋白质吸附的图案化功能结构表面.     

Temperature-responsive magnetite/PEO-PPO-PEO block copolymer nanoparticles for controlled drug targeting delivery

In this study, temperature-responsive magnetite/polymer nanoparticles were developed from iron oxide nanoparticles and poly(ethyleneimine)-modified poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymer. The particles were characterized by TEM, XRD, DLS, VSM, FTIR, and TGA. A typical product has an approximately 20 nm magnetite core and an approximately 40 nm hydrodynamic diameter with a narrow size distribution and is superparamagnetic with large saturation magnetization (51.34 emu/g) at room temperature. The most attractive feature of the nanoparticles is their temperature-responsive volume-transition property. DLS results indicated that their average hydrodynamic diameter underwent a sharp decrease from 45 to 25 nm while evaluating the temperature from 20 to 35 degrees C. The temperature-dependent evolution of the C-O stretching band in the FTIR spectra of the aqueous nanoparticles solution revealed that thermo-induced self-assembly of the immobilized block copolymers occurred on the magnetite solid surfaces, which is accompanied by a conformational change from a fully extended state to a highly coiled state of the copolymer. Consequently, the copolymer shell could act as a temperature-controlled "gate" for the transit of guest substance. The uptake and release of both hydrophobic and hydrophilic model drugs were well controlled by switching the transient opening and closing of the polymer shell at different temperatures. A sustained release of about 3 days was achieved in simulated human body conditions. In primary mouse experiments, drug-entrapped magnetic nanoparticles showed good biocompatibility and effective therapy for spinal cord damage. Such intelligent magnetic nanoparticles are attractive candidates for widespread biomedical applications, particularly in controlled drug-targeting delivery.     

PEO-PPO-PEO在生物医用材料方面的研究进展

聚氧乙烯-聚氧丙烯-聚氧乙烯三嵌段共聚物因其具有良好的生物相容性和蛋白抗性,近年来在生物医用材料中的应用越来越广泛.聚氧乙烯-聚氧丙烯-聚氧乙烯水溶液具有温度敏感的胶束化和热可逆凝胶化特点,被认为是一种具有许多优点的药物传输载体,药物与胶束的核心结合增加了药物的溶解性、代谢稳定性和体内循环时间.本文对聚氧乙烯-聚氧丙烯-聚氧乙烯在生物医用方面的研究进展进行了综述,并重点介绍了其在药物传输载体,组织工程等方面的研究进展.     

链霉亲和素-异硫氰酸荧光素偶联核壳型Fe_3O_4/Au纳米晶的合成及性质

采用改进的Polyol合成法,以PEO-PPO-PEO为表面活性剂制备了链霉亲和素-异硫氰酸荧光素偶联的Fe3O4/Au纳米粒子;利用透射电镜和X射线衍射仪分析证实了Fe3O4/Au的核壳型纳米结构,确定了其粒径和分布;采用紫外-可见吸收光谱仪和荧光光谱仪测定了所制备的纳米粒子的光学活性和荧光特性,并采用振动样品磁强计(VSM)测量了其磁化率.结果表明,所制备的Fe3O4/Au纳米粒子具有光学活性和荧光特性,以及优异的磁性.     

Single-step synthesis and stabilization of metal nanoparticles in aqueous pluronic block copolymer solutions at ambient temperature

A single-step synthesis of gold nanoparticles with an average diameter of approximately 10 nm from hydrogen tetrachloroaureate(III) hydrate (HAuCl4.3H2O) has been achieved in air-saturated aqueous solutions that contain poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers but not any other reducing agent. These amphiphilic block copolymers act as both reductants and colloidal stabilizers and prove very efficient in both functions. The formation of gold nanoparticles is controlled by the overall molecular weight and relative block length of the block copolymer. The synthesis procedure reported here is environmentally benign and economic, as it involves the minimum possible number of components: it uses water as the solvent, it uses commercially available polymers, it proceeds fast to completion, and it results in a "ready-to-use" product.     

Facile fabrication and characterization of novel polyaniline/titanate composite nanotubes directed by block copolymer

In this work, we present a facile method for preparation of novel polyaniline(PANI)/titanate composite nanotubes by in situ chemical oxidative polymerization directed by poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymer. The block copolymer adsorbed onto the surface of the titanate nanotubes acts as a soft template. The obtained nanocomposite has a core-shell structure in which titanate nanotubes are encapsulated by uniform PANI layers. Their structure and morphology were characterized by various experimental techniques. A possible formation mechanism of composite nanotubes is also proposed in the paper.     

Interaction of urea with pluronic block copolymers by 1H NMR spectroscopy

Solution 1H NMR techniques were used to characterize the interaction of urea with poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymers. The urea was established to interact selectively with the PEO blocks of the block copolymer, and the interaction sites were found not to change with increasing temperature. Such interactions influence the self-assembly properties of the block copolymer in solution by increasing the hydration of the block copolymers and stabilizing the gauche conformation of the PPO chain. Therefore, urea increases the critical micellization temperature (CMT) values of PEO-PPO-PEO copolymers, and the effect of urea on the CMT is more pronounced for copolymers with higher PEO contents and lower for those with increased contents of PPO segments.     

Electrochemical deposition of mesoporous nickel hydroxide films from dilute surfactant solutions

A series of micelle-templated mesoporous nickel hydroxide films were prepared by electrochemical deposition from dilute surfactant solutions by using different types of template and by varying plating solvent composition. Lamellar mesostructured Ni(OH)2 films are obtained with only anionic surfactant sodium dodecyl sulfate (SDS) as the template. In particular, a unique cooperative assembly fashion, that is, the combination between Ni2+ and a complex composed of the primary template SDS and a cosurfactant, such as triblock poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) copolymers and poly(ethylene glycol), was explored, by which two-dimensional hexagonal mesoporous Ni(OH)2 films were electrodeposited. Meanwhile, the deposition medium also plays a crucial role in determining the mesostructure of Ni(OH)2 films. For the composite nickel hydroxide films deposited from aqueous solution or dilute aqueous solution of ethylene glycol (<20 wt %) in the presence of SDS or the SDS-poly(alkylene oxide) polymer complexes, a mixed lamellar phase with d(001) = 37.4 A and d(001) = 28.5 A was obtained. However, single lamellar phase with d(001) = 37.4 A was electrodeposited from concentrated aqueous solutions of ethylene glycol (> or = 20 wt %). Furthermore, such deposition baths have access to hexagonal mesoporous nickel hydroxide films with d(100) = 37.4 A at 70 degrees C with the SDS-poly(alkylene oxide) polymer complexes as the templates. Within the potential window for Ni(OH)2, the morphology and quality of mesostructured films are significantly dependent on the deposition potential, while the mesostructures of the composite films always remain unchanged.     

Mechanism of gold metal ion reduction, nanoparticle growth and size control in aqueous amphiphilic block copolymer solutions at ambient conditions

Spontaneous formation and efficient stabilization of gold nanoparticles with an average diameter of 7 approximately 20 nm from hydrogen tetrachloroaureate(III) hydrate (HAuCl4.3H2O) were achieved in air-saturated aqueous poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymer solutions at ambient temperature in the absence of any other reducing agent. The particle formation mechanism is considered here on the basis of the block copolymer concentration dependence of absorption spectra, the time dependence (kinetics) of AuCl4- reduction, and the block copolymer concentration dependence of particle size. The effects of block copolymer characteristics such as molecular weight (MW), PEO block length, PPO block length, and critical micelle concentration (cmc) are explored by examining several PEO-PPO-PEO block copolymers. Our observations suggest that the formation of gold nanoparticles from AuCl4- comprises three main steps: (1) reduction of metal ions by block copolymer in solution, (2) absorption of block copolymer on gold clusters and reduction of metal ions on the surface of these gold clusters, and (3) growth of metal particles stabilized by block copolymers. While both PEO and PPO blocks contribute to the AuCl4- reduction (step 1), the PEO contribution appears to be dominant. In step 2, the adsorption of block copolymers on the surface of gold clusters takes place because of the amphiphilic character of the block copolymer (hydrophobicity of PPO). The much higher efficiency of particle formation attained in the PEO-PPO-PEO block copolymer systems as compared to PEO homopolymer systems can be attributed to the adsorption and growth processes (steps 2 and 3) facilitated by the block copolymers. The size of the gold nanoparticles produced is dictated by the above mechanism; the size increases with increasing reaction activity induced by the block copolymer overall molecular weight and is limited by adsorption due to the amphiphilic character of the block copolymers.     

Rheo-optical properties of silicone oil emulsions in the presence of polymer emulsifiers

Oil in water emulsions prepared by dispersion of silicone oils into an aqueous solution of hydroxylpropyl methyl cellulose (HPMC) or poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers were characterized by measurements of steady-state shear viscosities, dynamic moduli, and stress-strain sweep curves coupled with optical microscopic observation. The emulsions prepared with HPMC showed solidlike viscoelastic responses and a clear yield stress, whereas the emulsions emulsified by PEO-PPO-PEO block copolymers indicated liquidlike viscoelastic behavior. The difference should be attributed to stronger protective colloidal effects, that is, the former emulsifiers form a more viscoelastic polymer layer adsorbed on the oil droplets than the latter ones. Moreover, the simultaneous optical microscopic observation showed that the emulsions stabilized by HPMC do not flow below the yield stress and beyond the yield stress the movements of oil droplets occur first.