双重Pickering乳液法制备聚丙烯酰胺多孔微球及应用

采用亲水性气相二氧化硅N20和疏水性气相二氧化硅H30复配表面活性剂制备O/W/O型双重乳液,以此为模板,聚合中间相,挥发内相制备聚丙烯酰胺(PAM)多孔微球,并用于染料分子亚甲基蓝的吸附。结果表明：乳液显微镜照片显示水油比对双重乳液的形成有很大的影响,当水油比(O₁/W)/O₂为(1/2)/2时,可得到稳定的双重乳液;扫描电镜(SEM)照片显示PAM多孔微球基本呈球形,但粒径不均匀,球体表面粗糙,内部为空心结构;激光粒度仪(DLS)结果表明PAM微球平均粒径为356nm,多分散系数(PDI)为0.718,比表面积为230m²/g,粒径分布宽;在吸附温度35℃、吸附时间5min时对亚甲基蓝的吸附率为98.89%,最大吸附率超过99%,在吸附速率和吸附率上均优于传统PAM吸附剂,本研究为染料废水的处理提供了新方法。     

Facile fabrication of nanocomposite microspheres with polymer cores and magnetic shells by Pickering suspension polymerization

Pickering suspension polymerization was used to prepare magnetic polymer microspheres that have polymer cores enveloped by shells of magnetic nanoparticles. Styrene was emulsified in an aqueous dispersion of Fe₃O₄ nanoparticles using a high shear. The resultant Pickering oil-in-water (o/w) emulsion stabilized solely by magnetic nanoparticles was easily polymerized at 70 °C without stirring. Fe₃O₄ nanoparticles act as effective stabilizers during polymerization and as building blocks for creating the organic–inorganic hybrid nanocomposite after polymerization. The fabricated magnetic nanocomposites were characterized by FTIR, XRD, TGA, DSC, GPC, XPS and SEM. The structures of the polymer core and the nanoparticle shell were analyzed. We investigated the effects on the products of the weight of Fe₃O₄ nanoparticles used to stabilize the original Pickering emulsions. Pickering suspension polymerization provides a new route for the synthesis of a variety of hybrid nanocomposite microspheres with supracolloidal structures.     

Evaluation of Pickering emulsions stabilized with nano-cellulose and nano-chitin treated with deep eutectic solvent

Developing bio-friendly and degradable Pickering emulsifiers as surfactants to replace traditional surfactants with bio-toxicity is imperative in the food, coating, cosmetics, and pharmaceutical industries. Nanocellulose and chitin can be used directly as an emulsifier to prepare Pickering o/w emulsions. As the concentration of nanoparticles increases, the stability of the emulsion also increases, and an overly large nanoparticle aspect ratio is not conducive to the stabilization of the emulsion. In comparison, nanocellulose-prepared Pickering emulsion has improved stability. Of these, nanocellulose prepared by DES with a molar ratio of 3:1 to LA:CC has been shown to have the best stability when used to equilibrate the oil/water mass ratio of 2/8. The Zeta potential is −38.4 mV, and the size of the droplets is the most uniform. With a mean droplet diameter of 770 nm. This study had certain research significance and reference value for the development of bio-friendly surfactants.     

TiO2纳米颗粒稳定的Pickering乳液用作防晒乳成分研究

采用烷基化改性的TiO_2纳米颗粒为稳定剂,化妆品级白油为油相,黄芪水溶液为水相,制备了一种载药Pickering乳液。利用TEM、接触角测试仪和光学显微镜对TiO_2纳米颗粒及载药Pickering乳液进行了表征。结果表明,该纳米颗粒分散性良好、尺寸均匀,具备良好的稳定乳液能力;通过紫外吸收测试,控制释放药物和清洗对照实验,表明该载药Pickering乳液具有较高的防晒效果和随光照时间控制释放药物以及易于从皮肤表面清洗的特性。     

细菌纤维素纳米晶稳定液体石蜡Pickering乳液的制备

采用生物法合成了高纯度的细菌纤维素(BC),通过浓硫酸水解制得细菌纤维素纳米晶(BCN)。以液体石蜡为油相,BCN为固体乳化剂,在超声作用下制得O/W型Pickering乳液。通过SEM,TEM,FT-IR,XRD,接触角测量仪及激光粒度和Zeta电位分析仪对BC及BCN进行了表征。考察了BCN质量浓度、水相p H和离子强度对Pickering乳液稳定性的影响。结果表明,BC在浓硫酸水解过程中发生了氧化反应,其水解主要发生在无定型区,使所得BCN的结晶指数高达97%。BCN悬浮液的粒径和Zeta电位值分别为462.5 nm和-40.8 m V,其三相接触角为95.7°,具有良好的乳化性能。在超声乳化作用下制得的乳液粒径大小为8.6~17.3μm。通过调控水相p H能够改变BCN表面电荷密度,从而改变乳液的稳定性,随着水相p H的增大,乳液相体积分数增大,乳液稳定性增强。随着Na Cl浓度的增大,乳液的稳定性降低,乳液相体积分数减小。此外,SEM的观测结果表明,BCN在稳定Pickering乳液过程中呈现纤维线条和聚集体颗粒2种形态。     

湿法球磨改性蒙脱土及其稳定液体石蜡/水Pickering乳液的制备

以钠基蒙脱土(Na-MMT)为原料,采用湿法球磨法制备双十二烷基二甲基溴化铵(DDAB)插层的改性蒙脱土(DDA-MMT),并在超声作用下乳化液体石蜡制得O/W型Pickering乳液。通过XRD、TEM、FT-IR、接触角测量仪和Zeta电位及激光粒度仪对DDA-MMT进行了表征。考察了DDA-MMT颗粒质量浓度、水相p H和离子强度对Pickering乳液稳定性的影响。实验结果表明,在球磨机械力作用下DDAB成功插入Na-MMT的片层间,使Na-MMT的平均粒径、Zeta电位和三相接触角分别由910.7 nm,-26.8 m V和121.7°变为603.8 nm,38.3 m V和86.9°。与Na-MMT颗粒相比,DDA-MMT颗粒更容易在油/水界面间聚集而具有更好的乳化稳定性。随着DDA-MMT颗粒质量浓度的增大,Pickering乳液液滴粒径减小,乳液体积分数增大,稳定性增强。当水相p H=6.26~8.36,c(Na Cl)=20 mmol/L时,由DDA-MMT颗粒乳化制备的Pickering乳液稳定性较佳。     

Suspension polymerization based on inverse Pickering emulsion droplets for thermo-sensitive hybrid microcapsules with tunable supracolloidal structures

Polymerization using Pickering emulsion droplets as reaction vessels is being developed to become a powerful tool for fabrication of hybrid polymer particles with supracolloidal structures. In this paper, two kinds of thermo-sensitive hybrid poly(N-isopropylacrylamide) (PNIPAm) microcapsules with supracolloidal structures were successfully prepared from suspension polymerization stabilized by SiO₂ nanoparticles based on inverse Pickering emulsion droplets. SiO₂ nanoparticles could self-assemble at liquid-liquid interfaces to form stable water-in-oil inverse Pickering emulsion. NIPAm monomers dissolving in suspended aqueous droplets were subsequently polymerized at different temperatures. The hollow microcapsules with SiO₂/PNIPAm nanocomposite shells were obtained when the reaction temperature was above the lower critical solution temperature (LCST) of PNIPAm. While the core-shell microcapsules with SiO₂ nanoparticles' shells and PNIPAm gel cores were produced when the polymerization was conducted at the temperature lower than LCST using UV light radiation. The supracolloidal structures with different cores could be tuned by simply changing reaction temperature, which was confirmed by confocal laser scanning microscopy and scanning electron microscopy. The interesting properties of both microcapsules were their ability of reversibly swelling during drying/wetting cycles and responsive to temperature stimulus. Such functional microcapsules may find applications in double control release system due to the presence of the supracolloidal structures and thermo-sensitivity.     

Porous Al2O3 ceramics with directional gradient pore structure modified by cobweb-bridged WO3 nanowires for oil/water emulsions separation

A novel Al₂O₃ ceramic membrane modified by cobweb-bridged WO₃ nanowires was successfully fabricated for oil/water emulsions separation. Freeze-casting was employed to obtain directional gradient Al₂O₃ porous ceramics at first. Then, the cobweb-bridged WO₃ nanowires were successfully introduced into the separation layer by in-situ hydrothermal synthesis to construct the WO₃ nanowires/Al₂O₃ membrane. Results showed that WO₃ nanowires increased the surface roughness from 45.9 nm to 54.8 nm, the instantaneous water contact angle (WCA) and underwater oil contact angle (UOCA) reached the optimum values of 8.5° and 157.8°, respectively. Construction of cobweb-bridged WO₃ nanowires not only achieved a high separating efficiency of oil/water emulsions up to 92.35%, but also maintained high permeation fluxes at around 1600 L/m²·h·bar. After 10 cycles, the separation efficiency of the membrane remained above 90%. Moreover, the WO₃ nanowires/Al₂O₃ membrane still maintained underwater superoleophobicity after being immersed in strongly acidic, alkaline, and saline solutions, showing a high UOCA above 150° for all tested oil. The WO₃ nanowires/Al₂O₃ membrane is promising in oil/water emulsions separation application for its high separation efficiency, durability, and excellent chemical stability.     

包载槲皮素P/O/W多重皮克林乳液的制备及表征

为解决槲皮素溶解度低透皮性能差的问题，以疏水二氧化硅AEROSIL?R202、亲水二氧化硅AEROSIL?200为乳化剂，一缩二丙二醇和甘油为内醇相，制备水包油包醇（P/O/W）多重Pickering乳液，用其对槲皮素进行了包载。考察了内醇相（一缩二丙二醇和甘油）质量分数、疏水二氧化硅AEROSIL?R202质量分数、水乳比、亲水二氧化硅AEROSIL?200质量分数对P/O/W多重Pickering乳液性能的影响，得到最佳制备条件为：内醇相〔m（甘油）：m（一缩二丙二醇）=6：4〕质量分数为20%、疏水二氧化硅质量分数为3%、m（水）：m（初乳）=5：5、亲水二氧化硅质量分数为2%。对各相染色用激光共聚焦显微镜（CLSM）观察证明，成功制备了P/O/W多重Pickering乳液。X射线衍射仪（XRD）结果表明，槲皮素经多重乳液包载后结晶峰消失，表明该多重乳液对槲皮素有良好的包载效果。离心法测定包载槲皮素P/O/W多重乳液载药量达0.45 %± 0.02%。体外透皮实验和猪皮CLSM显示，槲皮素经该多重乳液包载后透皮性能得到改善，这主要是由于槲皮素在内醇相〔m（甘油）：m（一缩二丙二醇）=6：4〕中的溶解度可达60±2.1 mg/g，远大于在水 (<0.5 μg/g)或油 (<1 mg/g)中的溶解度。     

A novel design of Al2O3-ZrO2 reticulated porous ceramics with hierarchical pore structures and excellent properties

The use of reticulated porous ceramics(RPCs) was of great interest in high-temperature catalytic application owing to their high surface area. In order to further optimize the pore structure and mechanical properties of RPCs, vacuum infiltration with CaCO₃-Al₂O₃ slurries process was applied to fabricate Al₂O₃-ZrO₂ RPCs with hierarchical pore structures. The pores within ceramic struts were prepared by processes of CaCO₃ decomposition and calcium hexaluminate grains growth. And the compressive residual stress was formed within multi-layered struts owing to the difference in the thermal expansion of coating layer and ceramic struts, which was established as a key factor in improving the mechanical properties and thermal shock resistance of RPCs. Furthermore, the size of pores within struts ranging from 5 μm to 14 μm affected the thermal shock resistance of RPCs significantly based on grey incidence analysis. And the potential of this materials as high-temperature catalyst supports was demonstrated.