膜乳化和微流控法制备单分散W／O乳液的研究

以油相为连续相、水相为分散相,分别采用SPG膜乳化法和微流控技术制备出了单分散W／O乳液。对两种制备单分散乳液的方法进行了系统比较。结果表明,微流控技术不仅更易操作,而且制备出的W／O乳液单分散性更好。     

一体式陶瓷外膜直接乳化法制备单分散水包油乳液

膜乳化法是靠膜两侧的压差使分散相通过微孔膜,以小液滴的形式分散在连续相中而形成乳状液的方法．与转一定体系、高压均化等传统制乳方法相比,膜乳化法所制得的乳液具有液滴尺寸均一、节能、剪应力小等特点,可应用于食品、医药、聚合物工业等领域．过去的十几年中,尽管在膜乳化方面进行了大量的工作,过程参数对乳滴尺寸的影响并未完全研究清楚．甚至在一些研究中,仅仅把平均乳滴直径作为分布参数．     

单分散油包水乳液制备的研究进展

单分散油包水(W/O)乳液在食品、化妆品、药剂以及高分子微球微囊合成等方面具有广泛的应用。该文综述了近年来单分散W/O乳液的主要制备方法及其基本原理,此外还简要介绍了其在单分散温敏性微球微囊和可生物降解微球微囊合成方面的应用,以期为单分散W/O乳液的制备提供参考。     

微流控法制备新型微颗粒功能材料研究新进展

微颗粒功能材料在药物传送与控制释放、活性物质封装保护、微反应以及微分离等方面具有极其广泛的应用。相对于传统的微颗粒制备方法,近年来发展起来的微流控技术为可控制备具有不同结构和功能的单分散微颗粒功能材料提供了一个更为优越的技术平台。综述了微流控法制备新型微颗粒功能材料的研究新进展,重点介绍了利用微流控法可控制备具有良好单分散性的球形、非球形、中空型、核-壳型、孔-壳型以及多腔室型功能微颗粒的研究现状。     

微流控法制备新型微颗粒功能材料研究新进展

微颗粒功能材料在药物传送与控制释放、活性物质封装保护、微反应以及微分离等方面具有极其广泛的应用。相对于传统的微颗粒制备方法,近年来发展起来的微流控技术为可控制备具有不同结构和功能的单分散微颗粒功能材料提供了一个更为优越的技术平台。综述了微流控法制备新型微颗粒功能材料的研究新进展,重点介绍了利用微流控法可控制备具有良好单分散性的球形、非球形、中空型、核-壳型、孔-壳型以及多腔室型功能微颗粒的研究现状。     

微流控模板法制备功能化非球形微颗粒研究新进展

功能化非球形微颗粒在生物医药、吸附、传感与检测等方面具有非常广泛的应用。相对于其他非球形微颗粒制备方法,近年来兴起的微流控技术,由于对微尺度流体具有超灵敏的操控特性,在制备和精确调控微米级功能材料方面具有很大的优势。通过精确控制流体在微尺度通道内的流动和剪切,微流控技术可以实现多种形态和结构的微尺度流体、乳液和纤维的可控构建,为非球形微颗粒的可控制造提供了优良的模板。同时,通过在制备过程中引入功能性材料,这些非球形微颗粒将具备更多的功能,从而极大地拓展和丰富了其应用范围。本文综述了近年来采用微流控技术制备功能化非球形微颗粒的研究新进展,重点介绍了以微流控技术构建得到的微流体、多相乳液及微纤维为模板可控制备功能化非球形微颗粒的研究现状。     

软模板法制备单分散中空有机硅微球

通过硅氧烷单体在碱性条件下的水解-聚合反应,制备出了单分散乳液,研究了乳化剂HLB、反应时间、乳化剂用量、单体用量等因素对乳液的影响。然后以该乳液为模板、有机硅为壳层进行包覆,得到了中空微球。采用纳米粒度及Zeta电位分析仪、SEM、TEM、EDS、FTIR对乳液及中空微球进行表征。结果表明,在室温条件下,反应时间为6h时能够制备出单分散性较好的乳液,通过改变乳化剂用量、单体用量,能够实现对乳液粒径的调控,调控范围346～472 nm。以该乳液为模板进行缓慢包覆,当乳化剂质量分数低于0.003%时,能够得到形貌规整的单分散中空微球,中空微球的主要成分为有机硅。与硬模板法相比,该模板通过乙醇洗涤即可除去,制备过程较为简单。     

W/O微乳体系酸催化水解硅酸乙酯合成单分散酸性超微二氧化硅

研究不同亲水亲油平衡值 (HLB)的Span80 Tween60表面活性剂复配体系对酸性水溶液微乳化增溶力的影响 ,最佳HLB值在 1 3左右 ,该体系用作超微或纳米粒子的微乳法合成体系。在水 (HNO3) /Span80 Tween60 /环己烷体系中水解硅酸乙酯(TEOS)合成了 1 1 0～ 550nm的单分散酸性超微二氧化硅粒子 ,研究了R(n水/n表)和H(n水/nTEOS)对粒径的影响 ,随着R的增大 ,粒径越小 ,达到最小值再增大 ;H越高 ,粒径越大。提出了W/O微乳体系酸催化水解TEOS合成二氧化硅粒子的过程模型 ,指出酸催化过程中缩聚凝结是晶核长大的重要方式     

制备单分散含单体O/W乳液的SPG膜乳化过程

采用Shirasu多孔玻璃（SPG）膜乳化法制备了单分散含对苯二甲酰氯（TDC）单体的O/W乳液,系统地研究了SPG膜乳化过程的影响因素.实验结果表明,采用SPG膜乳化法制备单分散O/W乳液时,选择阴离子表面活性剂比考虑亲水亲油平衡（HLB）匹配更重要;增大分散相或连续相的黏度,能够改善乳液的单分散性和稳定性;随着单体浓度增加,乳液的单分散性变差,液滴的平均粒径逐渐变小.当SPG膜孔径大于1.0 μm左右时,可得到单分散的含TDC单体乳液;而当孔径小于1.0 μm左右时,水分子更容易扩散并溶解到油水界面甚至油相内部与TDC生成对苯二甲酸（TPA）,TPA积累到一定程度在油水界面上析出将膜孔堵塞,从而无法制得单分散乳液.随着乳化时间增长,乳液的平均直径逐渐变小、单分散性逐渐变差.     

反相微乳法制备纳米CaCO3

采用水(溶液)/Triton X-100/环已烷/正戊醇反相微乳体系,制备出了粒径分布均匀、尺寸在10~30 nm范围内的CaCO3纳米颗粒. 对不同w0、反应物浓度、陈化时间等因素的影响进行了研究,获得了最佳的反应条件. 所得产物利用透射电子显微镜分析进行了表征.     

石蜡油w／o／w型多重乳液的制备及其对维生素C的包裹

以多重乳液相对体积为衡量标准,探讨了石蜡油、乳化剂、以及第一相质量分数对石蜡油w／o／w型多重乳液稳定性的影响。结果表明制备石蜡油w／o／w型多重乳液的较佳条件为：第一相中石蜡油和乳化剂Span80质量分数分别为40％和8％,第一相质量分数为65％,乳化剂Tween80质量分数为1％。采用透析-紫外分光光度法研究了该多重乳液对维生素c的包裹能力,结果表明：多重乳液可以有效包裹维生素C,包裹率达98．55％,且能缓慢释放被包裹的维生素C。     

以碳酸钙为模板中空羟基磷灰石微球的合成

水浴条件下,中空球形碳酸钙(HSCCs)与磷酸氢二钠溶液反应成功合成了中空羟基磷灰石微球(HHMs).利用X射线衍射(XRD)、扫描电子显微镜(SEM)、傅里叶红外光谱(FTIR)对合成的中空羟基磷灰石微球的组成、结构、形貌进行了表征.结果表明,羟基磷灰石(HA)由模板碳酸钙直接转化而成,羟基磷灰石微球由杂乱分布的层片状晶粒聚集而成中空结构,直径约为4 μm,并对转化反应机理进行了初步探讨.     

Pickering乳液法制备复合壳层微胶囊及其在涂料中的应用

以水包油(O/W)型Pickering乳液为模板,经UV光聚合法制备复合壳层中空微胶囊,探究了乳化剂纳米粒子的加入方式、粒径和光敏低聚物PUA对微胶囊壳层的影响,并将微胶囊加入到树脂涂层中,探究微胶囊作为填料对涂层基本性能的影响。使用傅立叶变换红外光谱、扫描电镜、光学显微镜、热重等仪器对微胶囊结构进行表征,并对涂层性能进行了测试。结果表明:乳化剂SiO₂-E纳米粒子加入到油相中制备得到的中空微球表面镶嵌有SiO₂-E纳米粒子;乳化剂纳米粒子粒径的增加,影响中空微球的形貌但对尺寸无影响;当PUA的质量分数从10%增加到30%时,中空微胶囊表面分布的纳米粒子减少,断裂伸长率从11.1%增加至34.5%,而最大拉伸应力从21.5 MPa降低至12.1 MPa。中空微胶囊加入到涂料中,随中空微胶囊含量的增加,涂层的铅笔硬度提高且附着力良好。     

玉米油W1/O/W2型多重乳状液稳定性的研究

高脂食品严重危害着人类健康,这引起人们对低脂食品的的不断追求,因此脂肪替代品的开发越来越受到人们重视。本试验以玉米油和生物高聚物为主要原料通过两步乳化法制备W1/O/W2多重乳状液作为脂肪替代品(FS),以离心稳定性为衡量标准,用显微镜直接观察,探讨了初复乳乳化工艺、各相相对体积比对玉米油W1/O/W2型多重乳状液体系稳定性的影响。结果表明:1.影响玉米油多重乳状液稳定性的主要因素有:复乳的乳化工艺,内水相与油相体积之比等。2.两步乳化工艺中第二步乳化工艺对复乳稳定性影响较大,其规律是随着乳化强度的提高,粒径减小,稳定性呈上升趋势,适宜的乳化条件为7200 r.min.1,13 min,而第一步乳化工艺对复乳稳定性几乎没有影响。3.内水相与油相、初乳与外水相均是影响复乳稳定性的主要因素,前者主要是依靠改变初乳黏度来影响复乳稳定性,后者主要是乳滴间范德华力与电排斥力共同作用的结果,适宜的体积比分别为1:4和1:1。     

Effect of Cryoprotectant and Freeze-Drying Process on the Stability of W/O/W Emulsions

In order to protect a hydrophilic drug and to prolong its further delivery, the formulation of multiple emulsions could be worthy. However, the double emulsions are not stable, their structure can change, leading to the formation of a single emulsion as the destruction of the system, and the drug can release easily from the globules in liquid state. The freeze-drying technology could be used to produce dry emulsion, the powder form being much more stable. The aim of this work was to study the influence of a cryoprotectant and a freeze-drying process on the stability of W/O/W emulsions. Samples were frozen at two different freezing rate (ν_f = 0.55°C/min and 1.25°C/min) and successively dried at two different sublimation temperature (T_s = - 10°C and - 20°C). The particle size distributions were measured by granulometer and UV spectrophotometer was performed to investigate the leakage of internal constituent. The glass transition temperature (T_g) of the double emulsions was analyzed by DSC. The particle sizes became even smaller after freeze drying, except when κ-carrageenan is used as a cryoprotectant. In that case, the particles became aggregated after freeze drying, whatever the process conditions. The mean size is considerably reduced when the globules are diluted at low concentration in glucose and trehalose solution. When the concentration is increased, the size distribution is not significantly affected. The leakage of the internal aqueous phase to the external one during freeze drying was measured as an indicator of the structure stability. It is affected by the nature of the cryoprotectant and the conditions of the freeze-drying process. The leakage of the internal phase was smaller when cycle III (ν_f = 1.25°C/min, T_s = - 10°C) was processed. From our experiments, we suppose that the water transfer from the inner phase to the outer aqueous phase results in the diminution of the globules size in double emulsion. The T_g of the double emulsions diluted with trehalose and glucose were determined at - 33.8°C and - 47.1°C. In contrast, the T_g of double emulsion with κ-carrageenan and HES did not appear.     

Effect of Cryoprotectant and Freeze-Drying Process on the Stability of W/O/W Emulsions

In order to protect a hydrophilic drug and to prolong its further delivery, the formulation of multiple emulsions could be worthy. However, the double emulsions are not stable, their structure can change, leading to the formation of a single emulsion as the destruction of the system, and the drug can release easily from the globules in liquid state. The freeze-drying technology could be used to produce dry emulsion, the powder form being much more stable. The aim of this work was to study the influence of a cryoprotectant and a freeze-drying process on the stability of W/O/W emulsions. Samples were frozen at two different freezing rate (ν _f  = 0.55°C/min and 1.25°C/min) and successively dried at two different sublimation temperature (T _s  = ? 10°C and ? 20°C). The particle size distributions were measured by granulometer and UV spectrophotometer was performed to investigate the leakage of internal constituent. The glass transition temperature (T _g ) of the double emulsions was analyzed by DSC. The particle sizes became even smaller after freeze drying, except when κ-carrageenan is used as a cryoprotectant. In that case, the particles became aggregated after freeze drying, whatever the process conditions. The mean size is considerably reduced when the globules are diluted at low concentration in glucose and trehalose solution. When the concentration is increased, the size distribution is not significantly affected. The leakage of the internal aqueous phase to the external one during freeze drying was measured as an indicator of the structure stability. It is affected by the nature of the cryoprotectant and the conditions of the freeze-drying process. The leakage of the internal phase was smaller when cycle III (ν _f  = 1.25°C/min, T _s  = ? 10°C) was processed. From our experiments, we suppose that the water transfer from the inner phase to the outer aqueous phase results in the diminution of the globules size in double emulsion. The T _g of the double emulsions diluted with trehalose and glucose were determined at ? 33.8°C and ? 47.1°C. In contrast, the T _g of double emulsion with κ-carrageenan and HES did not appear.     

多重乳化体在化妆品中应用的研究进展

综述了多重乳化体的乳化剂、水相、油相等组成及制备工艺对多重乳化体的稳定性与生成率的影响;介绍了多重乳化体在化妆品中对活性物的包裹、缓释及隔离等的应用;指出制备稳定的多重乳化体的研究方向。     

Interfacial Crystallization of Diacylglycerols Rich in Medium‐ and Long‐Chain Fatty Acids in Water‐in‐Oil Emulsions

The effects of diacylglycerols rich in medium‐ and long‐chain fatty acids (MLCD) on the crystallization of hydrogenated palm oil (HPO) and formation of 10% water‐in‐oil (W/O) emulsion are studied, and compared with the common surfactants monostearoylglycerol (MSG) and polyglycerol polyricinoleate (PGPR). Polarized light microscopy reveals that emulsions made with MLCD form crystals around dispersed water droplets and promotes HPO crystallization at the oil‐water interface. Similar behavior is also observed in MSG‐stabilized emulsions, but is absent from emulsions made with PGPR. The large deformation yield value of the test W/O emulsion is increased four‐fold versus those stabilized via PGPR due to interfacial crystallization of HPO. However, there are no large differences in droplet size, solid fat content (SFC), thermal behavior or polymorphism to account for these substantial changes, implying that the spatial distribution of the HPO crystals within the crystal network is the driving factor responsible for the observed textural differences. MLCD‐covered water droplets act as active fillers and interact with surrounding fat crystals to enhance the rigidity of emulsion. This study provides new insights regarding the use of MLCD in W/O emulsions as template for interfacial crystallization and the possibility of tailoring their large deformation behavior. Practical Applications: MLCD is applied in preparing W/O emulsion. It is found that MLCD forms unique interfacial Pickering crystals around water droplets, which promote the surface‐inactive HPO nucleation at the oil‐water interface. Thus MLCD‐covered water droplets act as active fillers and interact with surrounding fat crystals, which can greatly enhance the rigidity of emulsion. This observation would provide a theoretical reference and practical basis for the application of the MLCD with appreciable nutritional properties in lipid‐rich products such as whipped cream, shortenings margarine, butter and ice cream, so as to substitute hydrogenated oil. MLCD‐stabilized emulsions can also be explored for the development of novel confectionery products, lipsticks, or controlled release matrices.