基于Ugi多组分反应的海藻酸酰胺衍生物改性二氧化硅纳米粒子的制备

采用海藻酸酰胺衍生物通过Ugi多组分反应制备了新颖的聚合物-二氧化硅(Oct-Alg-Si O_2)纳米粒子.通过氢核磁共振波谱(~1H NMR)和X射线光电子能谱(XPS)对Oct-Alg-Si O_2的结构和表面元素组分进行了表征.采用透射电子显微镜(TEM)、Zeta电位和激光粒度分析仪对Oct-Alg-Si O_2的形貌、粒径和胶体性能进行了探索.结果表明,海藻酸酰胺衍生物共价接枝到氨基二氧化硅(Si O_2-NH_2)纳米粒子的表面,提高了其平均直径,调控了其Zeta电位,在水介质中能够表现出良好的分散稳定性.以10%的液体石蜡为油相,采用Oct-Alg-Si O_2制备了Pickering乳液.在油水界面能够形成液滴粒径为5.7μm的稳定Pickering乳液.随着水相p H值的增大,乳液体积分数增大,稳定性增强.细胞相容性实验结果表明,Oct-Alg-Si O_2纳米粒子具有极好的生物相容性.     

反相微乳液模板原位聚合制备纳米氯化银/聚甲基丙烯酸甲酯及其结构表征

用甲基丙烯酸甲酯(MMA)作油相,反相胶束微乳液作为模板,制备了纳米氯化银(AgCl)粒子,再进行原位聚合制备了纳米氯化银/聚甲基丙烯酸甲酯(AgCl/PMMA)复合材料.透射电镜(TEM)分析表明,纳米AgCl的尺寸为20～80 nm.扫描电镜(SEM)测试表明纳米AgCl粒子均匀地存在于PMMA基材中.红外分析证明,胶束中水和表面活性剂AOT的羰基在MMA聚合后微观环境发生变化,纳米粒子同聚合物之间有吸附行为.动态力学(DMTA)分析复合材料,发现纳米AgCl粒子与聚合物之间存在强烈相互作用,形成了中间相层(interphase layer),改变了聚合物的动态力学性能.     

用聚合物乳液粒子构造纳米孔隙超低反射表面

由于粒子堆积膜的孔隙率有限,用聚合物乳液直接组装的纳米孔隙膜在膜厚和折射率的调节能力方面都受到限制,需要可以单独调控粒子膜孔隙率的手段.将聚甲基丙烯酸甲酯(PMMA)和聚苯乙烯(PS)的二元混合乳液在PMMA基板上旋涂,再用环己烷选择性溶去PS粒子得到了超低反射的纳米孔隙膜.改变混合乳液的组成可以调节多孔膜的空隙率,使多层纳米孔隙膜的有效折射率从1.36降低到1.07;调节旋涂速度和成膜乳液的浓度可以控制孔隙膜的厚度.在优化的条件下,在PMMA基板上制备的孔隙膜在波长585nm处的最低反射率仅0.03%、在450～800nm的可见光谱范围内的平均反射率低于0.4%.以本方法制备的纳米孔隙膜有较好的稳定性,在水中用超声波清洗30min后,膜的低反射性能几乎不变.     

纳米玉米醇溶蛋白微球稳定的O/W型Pickering乳液

利用相分离工艺制备玉米醇溶蛋白(zein)纳米微球,微球粒径可控制在40 nm左右;经旋转蒸发制得zein溶胶体系,zein溶胶具有明显的丁达尔现象,静置数月不聚沉,Zeta电位法测得zein微球在pH值为4.0时分散性能最佳。以纳米zein微球为固相稳定剂制备O/W型Pickering乳液,考察了zein胶体加入量、油水体积比等因素对乳液稳定性的影响。实验结果表明,zein胶体加入量的质量分数控制为0.4%,高油水体积比将有利于Pickering乳液的长时间稳定。基于zein分子的两亲结构和界面组装特点,提出了zein微球稳定Pickering乳液的作用机制。     

浓乳液双相聚合方法制备异形聚合物粒子

采用浓乳液双相聚合方法,成功制备了聚丙烯酸丁酯(PBA)的异形粒子,通过在连续相中引入聚合物隔层,大大提高了浓乳液聚合过程中的稳定性,探讨了隔层种类对浓乳液稳定性的影响,并研究了浓乳液分散相体积分数和交联剂用量对PBA粒子异形程度的影响,并结果表明,浓乳液双相聚合过程中,分散相体积分数越高,交联剂用量越高,PBA粒子的异形程度越大。     

多肽修饰的纳米金加速油-水界面酶促反应

用固相合成法制备阳离子氨基酸组成的多肽,再将其连接到巯基化合物上,用于纳米金表面配体交换,制备阳离子多肽修饰的纳米金,并研究了这种纳米粒子对油-水(O/W)乳液界面酶促反应速度的影响.结果发现,将含有荧光底物的乳滴同酶直接混合时,45 min内溶液中未检测到荧光信号变化,但向该溶液中加入纳米粒子后溶液中荧光信号立即增强.出现该现象的主要原因是,当乳液界面酶促反应体系中含有纳米粒子时,纳米粒子表面的阳离子多肽同时吸附带负电荷的酶和乳液,迅速屏蔽酶与乳液之间的电荷排斥,使酶与乳液中的底物能有效接触,加速酶促反应进行;通过选用不同的油相制备乳液,调控纳米粒子与乳液之间的氢键作用,还可使酶促反应速度进一步提高.     

基于氧化淀粉的新型Pickering苯丙乳液表面施胶剂的合成

以苯乙烯、丙烯酸丁酯为单体,过硫酸铵为引发剂,氧化淀粉作固体粒子乳化剂,采用无皂乳液聚合的方法来制备Pickering苯丙聚合物乳液,考察了不同含量的氧化淀粉对乳液固含量、转化率、卡伯值以及稳定性的影响,并对制备的Pickering苯丙聚合物乳液进行了粒径、红外光谱表征,当氧化淀粉的含量为2%时,制备的Pickering苯丙聚合物乳液转化率为96%,粒径为264.4nm,卡伯值为71.4g/m~2,抗水性和稳定性较好.     

贯通多孔聚合物微球的制备及其应用

采用高内水相双重乳液模板法制备贯通多孔聚合物微球,并将其应用于催化剂负载和Cu2+吸附.首先,通过增加水相,使单一小分子表面活性剂12-丙烯酰氧-9-油酸(AOA)稳定的反相高内相乳液(W/O HIPEs)发生相转变,一步制备出高内水相双重乳液;然后以此为模板,采用辐射法和引发剂引发聚合两种方式制备聚(苯乙烯-二甲基丙烯酸乙二醇酯)微球.通过扫描电镜观察发现,采用辐射法聚合能够得到贯通多孔的聚合物微球,而化学法聚合只能得到中空的封闭微球.将贯通多孔微球水解使其羧基化,用于铜离子的吸附.结果表明水解后多孔微球对Cu2+的吸附量随p H值的增加先增后减,在p H=5时达到最高值175 mg/g(2.75 mmol/g).此外,利用原位生成的方式,在贯通多孔微球上负载Pd纳米粒子,并将其用于催化肉桂醛加氢反应.结果表明水解多孔微球比未水解多孔微球具有更高的催化效率;热重分析和透射电子显微镜观察显示,水解多孔微球比未水解多孔微球能够负载更多的Pd纳米粒子,且纳米粒子分散更均匀.     

Pickering乳滴模板法制备超粒子结构有机/无机杂化微球

Pickering乳滴模板法制备有机/无机杂化的核壳微球越来越引起人们的关注,主要因为该方法制备出的微球具有以无机粒子为壳层的超粒子结构(supracolloidal structure),能够赋予微球独特的功能.胶体粒子在乳滴表面自组装形成有序的球面胶体壳,得到稳定Pickering乳液,固定乳滴表面的胶体粒子来制备核壳结构的微球或者以胶体粒子为壳层的微胶囊(colloidosome).本文综述了我们课题组以Pickering乳滴模板法制备超粒子结构有机/无机杂化微胶囊包括实心微球方面的工作.我们选择具有不同性能、种类的胶体粒子以及具有不同性质和功能的核材料,采用Pickering乳滴模板法,对吸附在乳滴表面的胶体粒子用不同的固定方法制备具有不同结构和性能的微球和微胶囊,利用基于多重Pickering乳液的聚合技术制备双纳米复合的超粒子结构多核聚合物微球.     

有机硅-丙烯酸酯聚合物乳液合成及粒径分析

通过种子乳液半连续法合成了有机硅改性丙烯酸酯聚合物乳液,并对其粒子形态及分布进行分析。结果表明:通过种子乳液半连续聚合工艺可制备出固含量42wt%,乳化剂含量4wt%(基于单体量)、窄分布纳米粒子的有机硅改性丙烯酸酯聚合物乳液。随反应进行,粒径分布变窄,平均粒径逐渐增大。随乳化剂中SDS与OP-10的摩尔比减少,粒径增大。     

Assembly of a Metal–Organic Framework into 3 D Hierarchical Porous Monoliths Using a Pickering High Internal Phase Emulsion Template

3D Hierarchical porous metal–organic framework (MOF) monoliths are prepared by using Pickering high internal phase emulsion (HIPE) template. Pickering HIPEs were stabilized solely by UiO‐66 MOF particles with internal phase up to 90 % of the volume. The effects of internal phase type and volume, as well as MOF particle concentration on the stability of resulting Pickering HIPEs were investigated. Furthermore, by adding small amount of polyvinyl alcohol (PVA) as binder or polymerization in the continuous aqueous phase, followed by freeze‐drying, two types of MOF‐based 3D hierarchical porous monoliths with ultralow density (as low as 12 mg cm^?3) were successfully prepared. This Pickering HIPE template approach provides a facile and practical way for assembling of MOFs into complex structures.     

Macroporous polymers obtained in highly concentrated emulsions stabilized solely with magnetic nanoparticles

Magnetic macroporous polymers have been successfully prepared using Pickering high internal phase ratio emulsions (HIPEs) as templates. To stabilize the HIPEs, two types of oleic acid-modified iron oxide nanoparticles (NPs) were used as emulsifiers. The results revealed that partially hydrophobic NPs could stabilize W/O HIPEs with an internal phase above 90%. Depending upon the oleic acid content, the nanoparticles showed either an arrangement at the oil-water interface or a partial dispersion into the oil phase. Such different abilities to migrate to the interface had significant effects on the maximum internal phase fraction achievable and the droplet size distribution of the emulsions. Highly macroporous composite polymers were obtained by polymerization in the external phase of these emulsions. The density, porosity, pore morphology and magnetic properties were characterized as a function of the oleic acid content, concentration of NPs, and internal phase volume of the initial HIPEs. SEM imaging indicated that a close-cell structure was obtained. Furthermore, the composite materials showed superparamagnetic behavior and a relatively high magnetic moment.     

Hydrophilic polymer foams with well‐defined open‐cell structure prepared from pickering high internal phase emulsions

Open‐cell hydrophilic polymer foams are prepared through oil‐in‐water Pickering high internal phase emulsions (HIPEs). The Pickering HIPEs are stabilized by commercial titania (TiO₂) nanoparticles with adding small amounts of non‐ionic surfactant Tween85. The morphologies, such as average void diameter and interconnectivity, of the foams can be tailored easily by varying the TiO₂ nanoparticles and Tween85 concentrations. Further, investigation of the HIPE stability, emulsion structure and the location of TiO₂ nanoparticles in resulting foams shows that the surfactant tends to occupy the oil‐water interface at the contact point of adjacent droplets, where the interconnecting pores are hence likely to be formed after the consolidation of the continuous phase. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Pickering乳液模板法制备Janus粒子

本文以SiO2粒子稳定的水包油(O/W)型Pickering乳液作为模板, 在乳液连续相进行SI-ATRP, 将聚合物刷接枝到SiO2粒子外半表面, 破乳得到半修饰的Janus粒子.     

High‐Internal‐Phase Pickering Emulsions Stabilized Solely by Peanut‐Protein‐Isolate Microgel Particles with Multiple Potential Applications

High‐internal‐phase Pickering emulsions have various applications in materials science. However, the biocompatibility and biodegradability of inorganic or synthetic stabilizers limit their applications. Herein, we describe high‐internal‐phase Pickering emulsions with 87 % edible oil or 88 % n‐hexane in water stabilized by peanut‐protein‐isolate microgel particles. These dispersed phase fractions are the highest in all known food‐grade Pickering emulsions. The protein‐based microgel particles are in different aggregate states depending on the pH value. The emulsions can be utilized for multiple potential applications simply by changing the internal‐phase composition. A substitute for partially hydrogenated vegetable oils is obtained when the internal phase is an edible oil. If the internal phase is n‐hexane, the emulsion can be used as a template to produce porous materials, which are advantageous for tissue engineering.     

Pure Protein Scaffolds from Pickering High Internal Phase Emulsion Template

The formation of hierarchical porous protein scaffolds from oil‐in‐water (o/w) high internal phase emulsions (HIPEs) stabilized by bovine serum albumin (BSA) protein nanoparticles (Pickering HIPE) is reported. The route consists of three principal steps. First, a stable o/w HIPE stabilized by BSA protein nanoparticles is formulated. Next, crosslinking the dispersed protein nanoparticles gives rise to a gel in the continuous water phase to freeze the emulsion's microstructure. Finally, removal of the oil components and water directly leads to a three dimensional, bimodal meso‐macroporous protein scaffold, which is suitable for a wide range of biomedical applications.     

Preparation of novel suspensions of ZnO/living block copolymer latex nanoparticles via pickering emulsion polymerization and their long term stability

In this work, we present the first Pickering emulsion polymerization with a controlled/living character. Pickering emulsion polymerization in the presence of a novel suspension of zinc oxide/poly(sodium 4‐styrenesulfonate) (ZnO/PSS^?) nanocomposite particles was applied to prepare ZnO/living block copolymer latexes. In the emulsion system, 1,1‐diphenylethene (DPE)‐controlled radical polymerization of poly(methyl methacrylate)‐b‐poly(butyl acrylate) (PMMA‐b‐PBA) was proceeded in oil phase. The nanocomposite particles of ZnO/PSS^? with an average diameter of 20 nm and negatively charged zeta potential around ?30 mV were synthesized via hydrothermal method then served as an effective emulsion stabilizer at the oil/water interface. Living polymerization was carried out using DPE‐capped PMMA as the macroinitiator and PMMA‐b‐PBA block copolymer latex was successfully prepared with coverage of ZnO/PSS^? nanoparticles. Narrow size distributions of the droplets as well as latex particles were obtained, and the livingness of block copolymers was comparable to that of emulsions stabilized by conventional surfactants. The controlled/living character in Pickering emulsion polymerization was slightly influenced by the amount of PSS^? immobilized into the ZnO/PSS^? nanoparticles, whereas it was significantly influenced by the weight ratios between ZnO/PSS^? and oil phase. The Pickering latexes showed excellent long term stability against either coalescence or sedimentation over several months. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Particle self-assembly at ionic liquid-based interfaces

This review presents an overview of the nature of ionic liquid (IL)-based interfaces and self-assembled particle morphologies of IL-in-water, oil- and water-in-IL, and novel IL-in-IL Pickering emulsions with emphasis on their unique phenomena, by means of experimental and computational studies. In IL-in-water Pickering emulsions, particles formed monolayers at ionic liquid–water interfaces and were close-packed on fully covered emulsion droplets or aggregated on partially covered droplets. Interestingly, other than equilibrating at the ionic liquid–water interfaces, microparticles with certain surface chemistries were extracted into the ionic liquid phase with a high efficiency. These experimental findings were supported by potential of mean force calculations, which showed large energy drops as hydrophobic particles crossed the interface into the IL phase. In the oil- and water-in-IL Pickering emulsions, microparticles with acidic surface chemistries formed monolayer bridges between the internal phase droplets rather than residing at the oil/water–ionic liquid interfaces, a significant deviation from traditional Pickering emulsion morphology. Molecular dynamics simulations revealed aspects of the mechanism behind this bridging phenomenon, including the role of the droplet phase, surface chemistry, and inter-particle film. Novel IL-in-IL Pickering emulsions exhibited an array of self-assembled morphologies including the previously observed particle absorption and bridging phenomena. The appearance of these morphologies depended on the particle surface chemistry as well as the ILs used. The incorporation of particle self-assembly with ionic liquid science allows for new applications at the intersection of these two fields, and have the potential to be numerous due to the tunability of the ionic liquids and particles incorporated, as well as the particle morphology by combining certain groups of particle surface chemistry, IL type (protic or aprotic), and whether oil or water is incorporated.     

A novel formulation of the pickering emulsion stabilized with silica nanoparticles and its thermal resistance at high temperatures

Stabilization of emulsions with solid particles can be used in several fields of oil and gas industry because of their higher stability. Solid particles should be amphiphilic to be able to make Pickering emulsions. This goal is achieved by using surfactants at low concentrations. Oil-in-water (o/w) emulsions are usually stabilized by surfactant but show poor thermal stability. This problem limits their applications at high-temperature conditions. In this study, a novel formulation for o/w stabilized emulsion by using silica nanoparticles and the nonionic surfactant is investigated for the formulation of thermally stable Pickering emulsion. The experiments performed on this Pickering emulsion formula showed higher thermal stability than conventional emulsions. The optimum wettability was found for DME surfactant and silica nanoparticles, consequently, in that region; Pickering emulsion showed the highest stability. Rheological changes were evaluated versus variation in surfactant concentration, silica concentration and pH. Scanning electron microscopy images approved the existence of a rigid layer of nanoparticle at the oil-water interface. Finally, the results show this type of emulsion remains stable in harsh conditions and allows the system to reach its optimum rheology without adding any further additives.     

高内相比乳液模板法合成多孔材料的研究进展

综述了以高内相比乳液作模板制备多孔材料的研究进展,介绍了油包水(W/O)乳液体系法、水包油(O/W)乳液体系法和超临界CO2法等制备方法、各种多孔材料的泡孔及通道直径、比表面积、密度等性能,以及这类多孔材料在生物医学、有机化学品清除、化学催化、水溶液中固体杂质分离、液相色谱、电化学传感器等领域的应用,并对其发展前景进行了展望。