乳化沥青及其乳化剂的发展与应用

概述了国内外乳化沥青及其乳化剂在建筑防水、道路维修养护等领域的应用概况,着重论述了乳化剂的分类、选择方法以及乳化剂复配体系的应用情况。根据我国的现状,指出了乳化沥青的高性能化、沥青乳化剂多样化将是主要的发展方向。     

Quantification of unadsorbed protein and surfactant emulsifiers in oil-in-water emulsions

Unadsorbed emulsifiers affect the physical and chemical behaviour of oil-in-water (O/W) emulsions. A simple methodology to quantify unadsorbed emulsifiers in the aqueous phase of O/W emulsions has been developed. Emulsions were centrifuged and filtered to separate the aqueous phase from the oil droplets and the concentration of unadsorbed emulsifiers in the aqueous phase determined. The quantification of unadsorbed surfactants based on the direct transesterification of their fatty acids was validated for Tween 20, Tween 80, citric acid ester (Citrem), Span 20 and monolauroyl glycerol. To determine unadsorbed proteins, results obtained with Folin-Ciocalteu reagent or UV-spectrophotometry were compared on emulsions stabilized by β-lactoglobulin (BLG), β-casein (BCN) or bovine serum albumin (BSA). The first method gave more accurate results especially during aging of emulsions in oxidative conditions. The whole methodology was applied to emulsions stabilized with single or mixed emulsifiers. This approach enables optimization of emulsion formulations and could be useful to follow changes in the levels of unadsorbed emulsifiers during physical or chemical aging processes.     

Roles of Various Bitumen Components in the Stability of Water-in-Diluted-Bitumen Emulsions

An experimental study was conducted to evaluate the effectiveness of the various components of Athabasca bitumen in stabilizing water-in-diluted-bitumen emulsions. The solvent used to dilute the very viscous bitumen was a mixture of 50:50 by volume of hexane and toluene. The various bitumen components studied were asphaltenes, deasphalted bitumen, and fine solids. It was found that asphaltenes and fine solids were the main stabilizers of the water-in-diluted-bitumen emulsions. Individually, the two components can stabilize water-in-diluted-bitumen emulsions. However, when both are present the capacity of the diluted bitumen to stabilize water emulsions is greatest. Emulsion stabilization tests indicated that whole bitumen had less capacity to stabilize water emulsions than asphaltenes and solids. This would indicate that the presence of the small molecules within the whole bitumen tends to lower the emulsion stability. Deasphalted bitumen acts as a poor emulsion stabilizer. Although deasphalted bitumen led to the least emulsion stabilization capacity, interfacial tension measurements showed that diluted deasphalted bitumen gave a greater decrease in the interfacial tension of water with diluent.     

Double emulsions stabilized by macromolecular surfactants

Multiple emulsions are emulsions within emulsions, stabilized traditionally by monomeric emulsifiers both at the inner and outer interface.     

颗粒乳化剂的研究及应用

近年来,颗粒乳化剂因其在食品、采油、化妆品、医药、催化以及功能纳米材料制备等领域具有潜在应用前景而备受关注。本文综述了近来颗粒乳化剂的研究进展,归纳了颗粒乳化剂的种类,包括:无机纳米粒子、表面改性或杂化的无机粒子、有机纳米粒子以及特殊的颗粒乳化剂Janus粒子;并对颗粒乳化剂能够在油水界面稳定吸附的热力学机理和动力学行为进行了阐述,颗粒乳化剂在油水界面接触角以及粒径大小是其在界面稳定吸附的关键参数,而颗粒在油水界面的排布方式则主要受粒子之间相互作用的影响。重点介绍了颗粒乳化剂的热点应用,包括:(1)利用颗粒乳化剂制备Pickering乳液,以及通过对颗粒乳化剂的功能化,使得Pickering乳液具备环境响应性(即pH、盐浓度、温度、紫外光、磁场敏感响应性);(2)以颗粒乳化剂为构筑基元、以Pickering乳液为模板制备Janus颗粒、Colloidosome、具有多级结构的粒子或膜,以及多孔结构材料;(3) Janus粒子在催化领域的应用。     

淀粉/丙烯酸反相乳液体系的稳定性研究

以丙烯酸(AA)单体的水溶液为水相,液体石蜡为油相,失水山梨醇三油酸酯(Span 85)和辛基苯基聚氧乙烯醚(Opan 10)为复合乳化剂,合成了淀粉/丙烯酸反相乳液;考察了乳化剂亲水亲油平衡值(HLB值)、油水比、乳化剂用量、单体浓度、温度对乳液稳定性和类型的影响.结果表明,合成淀粉/丙烯酸稳定反相乳液体系的适宜条件...     

Supramolecular Polymer Emulsifiers for One-step Complex Emulsions

Complex emulsions,such as double emulsions and high-internal-phase emulsions,have shown great applications in the fields of drug delivery,sensing,catalysis,oil-water separation and self-healing materials.Their controllable preparation is at the forefront of interface and material science.Surfactants and polymers have been widely used as emulsifiers for building complex emulsions.Yet some inherent disadvantages exist including multi-step emulsifications and low production efficiency.Alternatively,supramolecular polymer emulsifier for complex emulsions via one-step emulsification is rising as a new strategy due to the ease of preparation.In this feature article,we review our recent progresses in using supramolecular polymer emulsifiers for the preparation of complex emulsions.Double emulsions and high-internal-phase emulsions are successfully prepared via one-step emulsification with the help of different supramolecular interactions including electrostatic,hydrogen bond,coordination interaction and dynamic covalent bond,which will be particularly emphasized in detail.In the end,a comprehensive prospect is given for the future development of this field.This article is expected to provide new inspirations for preparing complex emulsions via supramolecular routes.     

Effects of compositions on the stability of polyols-in-oil-in-water (P/O/W) multiple emulsions

Polyols-in-oil-in-water (P/O/W) multiple emulsions were successfully prepared by using polyols as inner aqueous phase to avoid instabilities caused by water. The influence of polyols, oils and emulsifiers on the morphology and stability of P/O/W multiple emulsions were studied and the stability mechanisms of this new kind of multiple emulsions were also explored. Glycerol that has the worst solubility in oil phase contributed to the formation of stable inner droplets which agree with the Ostwald Ripening theory. Mineral oil worked well with the system proving that oils possessing similar solubility parameters with the hydrophobic group of emulsifiers benefited for system stability. Several typical surfactants had been investigated in this article, and it turned out that emulsifiers Cetyl PEG/PPG-10/1 Dimethicone and the block copolymer Poloxamer 407 were suitable for the P/O/W system. The stability of the system affected by different compositions was evaluated based on microscopic observation and rheological measurements. The novel multiple emulsions will provide enlightening recommendations for future investigations and applications in cosmetic, food and pharmaceuticals, including drug delivery and the encapsulation of hydrophilic actives and actives that are soluble in polyols.     

Formula Optimization of Emulsifiers for Preparation of Multiple Emulsions Based on Artificial Neural Networks

Formulation optimization of emulsifiers for preparing multiple emulsions was performed in respect of stability by using artificial neural network (ANN) technique. Stability of multiple emulsions was expressed by the percentage of reserved emulsion volume of freshly prepared sample after centrifugation. Individual properties of multiple emulsions such as droplet size, δ, viscosity of the primary and the multiple emulsions were also considered. A back‐propagation (BP) network was well trained with experimental data pairs and then used as an interpolating function to estimate the stability of emulsions of different formulations. It is found that using mixtures of Span 80 and Tween 80 with different mass ratio as both lipophilic and hydrophilic emulsifiers, multiple W/O/W emulsions can be prepared and the stability is sensitive to the mixed HLB numbers and concentration of the emulsifiers. By feeding ANN with 39 pairs of experimental data, the ANN is well trained and can predict the influences of several formulation variables to the immediate emulsions stability. The validation examination indicated that the immediate stability of the emulsions predicted by the ANN is in good agreement with measured values. ANN therefore could be a powerful tool for rapid screening emulsifier formulation. However, the long‐term stability of the emulsions is not good, possibly due to the variation of the HLB number of the mixed monolayers by diffusion of emulsifier molecules, but can be greatly improved by using a polymer surfactant Arlacel P135 to replace the lipophilic emulsifier.     

Synergistic interaction in emulsions stabilized by a mixture of silica nanoparticles and cationic surfactant

Using a range of complementary experiments, a detailed investigation into the behavior of dodecane-water emulsions stabilized by a mixture of silica nanoparticles and pure cationic surfactant has been made. Both emulsifiers prefer to stabilize o/w emulsions. At high pH, particles are ineffective emulsifiers, whereas surfactant-stabilized emulsions become increasingly stable to coalescence with concentration. In mixtures, no emulsion phase inversion occurs although synergism between the emulsifiers leads to enhanced stability at either fixed surfactant concentration or fixed particle concentration. Emulsions are most stable under conditions where particles have negligible charge and are most flocculated. Freeze fracture scanning electron microscopy confirms the presence of particle flocs at drop interfaces. At low pH, particles and surfactant are good emulsifiers alone. Synergism is also displayed in these mixtures, with the extent of creaming being minimum when particles are most flocculated. Experiments have been undertaken in order to offer an explanation for the latter synergy. By determining the adsorption isotherm of surfactant on particles in water, we show that surfactant addition initially leads to particle flocculation followed by re-dispersion. Using suitable contact angle measurements at oil-water-solid interfaces, we show that silica surfaces initially become increasingly hydrophobic upon surfactant addition, as well as surfactant adsorption lowering the oil-water interfacial tension. A competition exists between the influence of surfactant on the contact angle and the tension in the attachment energy of a particle to the interface.     

铜电极上Zn—Co—P合金电沉积行为

铜电极上Ｚｎ┐Ｃｏ┐Ｐ合金电沉积行为黄清安＊陈永言邓伯华（武汉大学化学系武汉４３００７２）关键词铜电极，Ｚｎ－Ｃｏ－Ｐ合金，电沉积１９９６－０４－２３收稿，１９９６－０９－１３修回国家自然科学基金资助课题为了提高Ｚｎ层的耐蚀性，出现了含磷的锌基合金，...     

Modeling phase separation and droplet size of W/O emulsions with oregano essential oil as a function of its formulation and homogenization conditions

Oregano essential oil emulsions (W/O) were prepared using different emulsifiers’ blend concentrations of Tween 80/Span 20, to study their phase separation during storage and to optimize the homogenization processing parameters by minimizing the droplet size of emulsions. Phase separation followed a second-order kinetic model, and relationships between the kinetic parameters and the blend concentrations of emulsifiers were established for determining the best emulsion formulations. The instability mechanism of emulsions demonstrated to be Ostwald ripening; therefore, by means of surface response methodology, mechanical homogenization parameters (11,700?rpm for 12 minutes at 1°C) were specified in order to minimize the droplet size of emulsions (1.02?±?0.12?µm).     

Multilayer emulsions stabilized by vegetable proteins and polysaccharides

There is great interest in the food, cosmetic and pharmaceutical industry in the use of proteins and polysaccharides as natural hydrocolloids to create novel emulsion systems with improved stability and functionality. For example, the electrostatic interaction between proteins and polysaccharides may be used to form oil-in-water (O/W) emulsions with multilayered interfacial membranes around oil droplets or multilayer emulsions. This type of emulsions have been developed using the layer-by-layer (LbL) technique, which consists of direct adsorption of an oppositely charged polyelectrolyte layer (e.g. polysaccharides) on a primary layer of ionic emulsifiers (e.g. proteins). The polymeric structure and electrical charge of proteins make them a special class of compounds very suitable for its utilization in the LbL technique. In recent years, the utilization of proteins as emulsifiers in food and pharmaceutical industry has been turning towards plants as a preferred alternative to animal-based sources. This article reviews the current understanding of the utilization of different vegetable proteins as emulsifier in order to stabilize O/W multilayer emulsion systems. Additionally, it highlights some potential applications of the multilayer emulsion technology in the industry, for improving the stability of emulsions to environmental stresses and for developing controlled or triggered release systems.     

Disjoining pressure isotherms of water-in-bitumen emulsion films

In the oil sands industry, undesirable water-in-oil emulsions are often formed during the bitumen recovery process where water is used to liberate bitumen from sand grains. Nearly all of the water is removed except for a small percentage (approximately 1 to 2%), which remains in the solvent-diluted bitumen as micrometer-sized droplets. Knowledge of the colloidal forces that stabilized these water droplets would help to increase our understanding of how these emulsions are stabilized. In this study, the thin liquid film-pressure balance technique has been used to measure isotherms of disjoining pressure in water/toluene-diluted bitumen/water films at five different toluene-bitumen mass ratios. Even though a broad range of mass ratios was studied, only two isotherms are obtained, indicating a possible change in the molecular orientation of surfactant molecules at the bitumen/water interfaces. At low toluene-bitumen mass ratios, the film stability appears to be due to a strong, short-range steric repulsion created by a surfactant bilayer. Similar isotherms were obtained for water/toluene-diluted asphaltene/water films, indicating that the surface active material at the interface probably originated from the asphaltene fraction of the bitumen. However, unlike the bitumen films, films of toluene-diluted asphaltenes often formed very rigid interfaces similar to the "protective skin" described by other researcher.     

Thermoanalytical and microscopical investigation of the microstructure of emulsions containing polymeric emulsifier

Polymeric emulsifiers provide exceptional stability to oil-in-water, water-in-oil or multiple emulsions by their steric stabilization. Pemulens as polymeric emulsifiers are able to stabilize o/w type emulsions because their short lipophilic part integrates into the oil droplets while their long hydrophilic part forms a micro gel around the droplet. In our present study the microstructure and integration of the polymeric emulsifier at the water-oil interface was investigated with thermogravimetric and microscopical methods. It was established that depending on the amount of both of the polymeric emulsifier and added coemulsifier the microstructure of the system changes.     

Bitumen-in-Water Emulsions: An Overview on Formation,Stability, and Rheological Properties

This paper describes the most relevant issues associated with the development of a technology; the formation of highly concentrated bitumen-in-water emulsions. Viscosity values for bitumen-in-water emulsions, containing between 70 and 85% (v/v) of bitumen, have been found to be several order of magnitude lower than the viscosity of the hydrocarbon itself. Thus, these emulsions, have potential applications in the processes of production, transportation, handling and commercialization of these extremely highly viscous hydrocarbons. The emulsions, the properties of which are discussed in this paper, were stabilized with mixtures of nonionic and natural surfactants (1,2) and formed using the HIPR (high internal phase ratio) technique (3). Information on the conditions required to produce emulsions with very narrow droplet diameter distributions is given. Results indicate that the mean droplet diameter, the droplet diameter distribution, and the bitumen volume fraction, significantly modify the rheological behavior. Emulsion stability was measured by following changes in the mean droplet diameter and in the rheological parameters with storage time.     

生物质快速热解油水相溶液超声乳化特性

使用生物油水相溶液与0# 柴油乳化,筛选了四种常用乳化剂和一种助乳化剂进行复配乳化实验,考察了复配乳化剂型号、乳化剂用量、超声作用时间对乳化效果的影响。结果表明,六种乳化液超过30d不破乳,与0# 柴油相比,密度和热值相差不大,含水量3%以下,黏度增大约40%,pH值降低一半。因素分析法表明,水相溶液与柴油质量比和不同的水相溶液对乳化效果影响较大。探讨了乳化机理,认为生物油水相溶液中水、醛、酸、酮等极性组分化合物稳定地被乳化剂包裹在W/O型乳化液液滴中,生物油水相溶液中少量的乙酸乙酯、芳香类化合物等则增溶于非离子乳化剂胶束中。热力学分析表明,超声乳化作用比静置作用具有更大的熵增,乳化液更趋于稳定平衡状态。     

Solid colloidal particles inducing coalescence in bitumen-in-water emulsions

Silica particles are dispersed in the continuous phase of bitumen-in-water emulsions. The mixture remains dispersed in quiescent storage conditions. However, rapid destabilization occurs once a shear is applied. Observations under the microscope reveal that the bitumen droplets form a colloidal gel and coalesce upon application of a shear. We follow the kinetic evolution of the emulsions viscosity, eta, at constant shear rate: eta remains initially constant and exhibits a dramatic increase after a finite time, tau. We study the influence of various parameters on the evolution of tau: bitumen droplet size and volume fraction, silica diameter and concentration, shear rate, etc.     

PREPARATION OF CLOUDY COCONUT OIL EMULSIONS CONTAINING DISPERSED Ti02 USING ATOMIZER

Food Grade Rutile TiO₂ was dispersed in coconut oil with the help of hydrophobic emulsifiers such as sorbitan esters and lecithin. The dispersed mixture was melted and blended with hydrophilic emulsifiers such as ethoxylated sorbitan esters and the preheated (60°C) blend was further sprayed by atomizer into cold water (20°C). The oil-in-water emulsions contained encapsulated TiO₂ in the internal phase. The technique is simple and allows preparation of stable emulsions with average droplet size of 1-10 microns.     

Thermosensitive pickering emulsion stabilized by poly(N-isopropylacrylamide)-carrying particles

Poly(N-isopropylacrylamide) (PNIPAM)-carrying particles were characterized as thermosensitive Pickering emulsifiers. Emulsions were prepared from various oils, such as heptane, hexadecane, trichloroethylene, and toluene, with PNIPAM-carrying particles. PNIPAM-carrying particles preferentially formed oil-in-water (O/W)-type emulsions with a variety of oils. All the emulsions stabilized by PNIPAM-carrying particles were stable for more than 3 months as long as they were stored at room temperature. However, when the emulsions were heated from room temperature to 40 degrees C, at which point the PNIPAM layer caused a coil-to-globule transition, phase separation occurred. Thus, by using thermosensitive PNIPAM-carrying particles as emulsifiers, the stability of the Pickering emulsions could be controlled by a slight change in temperature.