微乳液聚合制备多孔高吸油甲基丙烯酸酯类树脂的研究

研究了双连续相微乳液聚合制备多孔高吸油树脂,以甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)为共聚单体(油相),水(H2O)/乙醇(EtOH)为混合水相,2,2′-偶氮二异丁腈(AIBN)为引发剂,采用十二烷基硫酸钠(SDS)和复配十二烷基硫酸钠/吐温80(SDS/T80)两种乳化体系,调节油相和水相比例,配制出双连续相微乳液.聚合在无搅拌下进行.研究了乳化体系、混合水相含量、单体配比、交联剂和引发剂用量等因素对树脂吸油性能的影响.结果表明,多孔高吸油树脂比同系无孔树脂的吸油速率大大提高,最快可以在2min内达到吸油饱和.树脂对苯,四氢呋喃,四氯化碳的吸油倍率分别达到15.5g/g,15.5g/g,31.7g/g.     

无表面活性剂微乳液体系：N,N－二甲基甲酰胺/呋喃甲醛/水

通常微乳液一般由四个组分构成：水相、油相、表面活性剂和助表面活性剂。本文报道了一种不含表面活性剂的微乳液体系(简称SFME),由呋喃甲醛(油相),水和N,N－二甲基甲酰胺(DMF)三组分构成,不含传统的表面活性剂。对其相行为进行了研究,发现存在一个单相微乳液区和一个两相平衡区。采用电导率法和冷冻蚀刻电镜(FF-TEM)考察了单相区域中微乳液的微结构,结果表明可分为油包水(O/W)、双连续(BC)和水包油(W/O)三个区域。液滴直径介于40-70nm。     

十二烷基磺酸钠微乳状液结构转变的电化学研究

制备了C12H25SO3Na-C4H9OH-C7H16-H2O四组分体系在km=W(C4H9OH)/W(C12H25SO3Na)=2时的拟三元相图。使用二茂铁和铁氰化钾作为电化学探针用循环伏安法测定了起始含油量为21％的无水混合物在滴加水过程中所形成的微太液的扩散系数。从扩散系数随含水量的变化确定微乳液的结构转变。含水量为20％－45％时生成油包水型微液;含水量大于65％时生成水包油型微乳液。当含水量在45％－65％之间时形成的是二连续型微乳液。电导率数据证实了循环伏安法的测定结果。     

Sugar-based microemulsion glass templates

Complex fluids comprising of surfactants with water and/or oil form a rich variety of dynamic self-assembled structures, ranging from spherical swollen micelles, viscous rod-like micelles, and bicontinuous microemulsions to ordered liquid crystalline phases. The wide range of practical and specialized applications of complex fluids has made them the subject of intense research for many decades. Here, we demonstrate for the first time how bicontinuous microemulsions containing equal masses of oil and sugar can be driven to the glassy state without phase separation at ambient temperatures by controlled desiccation of sugar-rich microemulsions. The robust nanostructure of these microemulsion glasses allows polymerization of hydrophobic liquid monomers within the interstices of the glassy microemulsion template without macroscopic phase separation. Yet after polymerization, the sugar and surfactant template can be easily removed by dissolution in water.     

Gelled polymerizable microemulsions. 2. Microstructure

Using bicontinuous microemulsions as templates opens a new field for the design of novel structures and thus novel materials, but has significant challenges due to the very small composition and temperature windows in which microemulsions are bicontinuous. In previous work we had shown that we can take a ternary base system (water-n-dodecane--C 13/15E 5), add monomer and cross-linker ( N-isopropylacrylamide and N, N'-methylenebisacrylamide) to the water phase, and add a gelator (12-hydroxyoctadecanoic acid) to the oil phase while remaining in the one-phase region of the phase diagram. It was also possible to allow the gelator to form an organogel by changing the temperature such that we crossed the sol--gel line, which fell within the one-phase region. In this work, we show conclusively that addition of the monomers and the gelator does not affect the microemulsion microstructure and that, even in the gelled state, the polymerizable microemulsion is indeed bicontinuous. 1H NMR self-diffusion, conductivity, and small-angle neutron scattering measurements all confirm the bicontinuous nature of the gelled polymerizable microemulsion.     

Nano-structured proton exchange membranes molded by polymerizing bi-continuous microemulsion

A unique type of nano-structured proton exchange membrane (PEM) has been fabricated through photo-polymerizing a bicontinuous microemulsion. This microemulsion is constituted by a polymerizable zwitterionic surfimer 3-((11-acryloyloxyundecyl)imidazoyl)propyl sulfonate (AIPS), 3-sulfopropylmethacrylate, potassium salt (SPM), acrylonitrile and water. As the resulting colloidal system maintains quasi-homogeneous state throughout the polymerization course, the inherent bicontinuous microemulsion structure was successfully transferred to the matrix of the polymer membrane. Such membranes are therefore composed of dual phase channels with ca. 1.5–2 nm of the hydrophilic channel breadth. This particular structural trait imparts to the membranes excellent proton conductivities of up to 10⁻¹ S cm⁻¹ as well as low methanol permeability. The DMFC single cell loaded with the demo PEM manifests ca. 20 mW cm⁻² of power output. The attributes of this PEM are elucidated from the bicontinuous structure of microemulsion.     

Variation of surface properties and textural features of spinel ZnAl2O4 and perovskite LaMnO3 nanoparticles prepared via CTAB-butanol-octane-nitrate salt microemulsions in the reverse and bicontinuous states

Two binary oxides, a spinel, ZnAl2O4, and a typical perovskite, LaMnO3, have been prepared via CTAB-1-butanol-n-octane-nitrate salt microemulsion in the reverse and bicontinuous states. The exact point of the reverse and bicontinuous states of the microemulsion used in the synthesis was determined by conductivity experiments. The materials obtained after heating at 800 degrees C were characterized by XRD analysis for their crystal structure, N2 porosimetry for their surface area and porosity, and SEM and TEM photography for their texture. The ZnAl2O4 spinel obtained via the reverse microemulsion appears in SEM in a more fragmented form and with a higher specific surface area (143.7 m(2)g(-1)), compared to the corresponding solid prepared via the bicontinuous microemulsion, which appears more robust with lower surface area (126.7 m(2)g(-1)). Nevertheless both materials reveal in TEM a sponge-like structure. The perovskite materials LaMnO3 prepared via the reverse microemulsion showed in SEM a peculiar doughnut-like texture, each doughnut-like secondary particle having a diameter of 2 microm. The corresponding sample developed via the bicontinuous microemulsion showed in SEM uniform secondary particles of size approximately 0.2 microm. Both perovskite samples LaMnO3 appear well crystallized with relative low surface areas, 23.7 m(2)g(-1) for the reverse sample and 10.9 m(2)g(-1) for the bicontinuous one. The TEM photographs reveal that both of them, of reversed and bicontinuous origin, are made up of primary nanoparticles in the size range 40-100 nm. In SEM those materials showed a different secondary structure.     

Microemulsion polymerization of acrylamide and styrene: Effect of the structures of reaction media

Isothermal phase diagrams of the system cetyltrimethylammonium bromide (CTAB)/n‐butanol/n‐octane/water were constructed, and the effect of the oil (n‐octane) contents on the microemulsions was studied at 40 °C. We determined the microemulsion structures of two systems, CTAB/n‐butanol/10% n‐octane/water and sodium dodecyl sulfonate (As)/n‐butanol/20% styrene/water, by conductivity measurements to investigate the polymerization of acrylamide and styrene in the two microemulsion systems. The polymerization kinetics of the water‐soluble monomer acrylamide in CTAB micelles and the different CTAB/n‐butanol/10% n‐octane/water microemulsion media [water‐in‐oil (W/O), bicontinuous (BC), and oil‐in‐water (O/W)] were studied with water‐soluble sodium bisulfite as the initiator. The maximum polymerization rate in CTAB micelles was found at the second critical micelle concentration. A mechanism of polyacrylamide formation and growth was proposed. A connection between the structures of the microemulsions and the polymerization rates was observed; the maximum polymerization rate occurred at two transition points, from W/O to BC and from BC to O/W, and the polyacrylamide molecular weights, which depended on the structures of the microemulsions, were also found. A square‐root dependence of the polymerization rates on the initiator concentrations was obtained in CTAB micelles and O/W microemulsion media. The polymerization of the oil‐soluble monomer styrene in different As/n‐butanol/20% styrene/water microemulsion media (W/O, BC, and O/W) was also investigated with different initiators: water‐soluble potassium persulfate and oil‐soluble azobisisobutyronitrile. A similar connection between the structures of the microemulsions and the conversions of styrene in CTAB/n‐butanol/10% n‐octane/water for the polymerization of acrylamide was observed again. The structures of the microemulsions had an important role in the molecular weights and sizes of polystyrene. The polystyrene particles were 10–20 nm in diameter in BC microemulsion media and 30–60 nm in diameter in O/W microemulsion media according to transmission electron microscopy. We determined the solubilization site of styrene in O/W microemulsion drops by ¹H NMR spectra to analyze the results of the microemulsion polymerization of styrene. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3320–3334, 2001     

丙烯酸酯及苯乙烯微乳体系的相行为及微乳聚合

甲基丙烯酸甲酯;十二烷基磺酸钠;十二烷基磺酸钠;丙烯酸酯及苯乙烯微乳体系的相行为及微乳聚合     

双连续相微乳液辐射聚合制备多孔材料的研究

利用6 0 Co γ射线在室温下辐照双连续相微乳液体系以制备多孔聚合物材料 ,试图在控制多孔材料的微孔结构形态和减少微乳液聚合过程中的相分离方面做一些探索 .通过电导率的测量分析微乳液的结构类型 ,并确定微乳液的双连续相区域范围 .微乳液聚合后所得的样品的孔结构和聚合前的微乳液结构类型有关 ,扫描电镜和热重分析的结果表明双连续相微乳液在聚合时容易发生相分离 ,未必能够得到开孔结构的聚合物 .但适当控制聚合前微乳液的组成 ,如选择合适的水油比例、交联剂的用量和加入一些功能性单体 (如甲基丙烯酸或丙烯酸钠 ) ,可以有效地抑制相分离 ,调节所得聚合物的结构形态 .     

Synthesis of sponge-like polymer dispersions via polymerization of bicontinuous microemulsions

Polymer gels with high water content are made by polymerization of hydrophilic/hydrophobic monomer mixtures in bicontinuous microemulsions. These structures can be described as a heterophasic, bicontinuous polymer colloid-in-water structure, the characteristic length of which is only indirectly influenced by the original microemulsion mixture.The structure formation and phase changes throughout the polymerization reaction are followed with rheology, polarization microscopy, and scanning and transmission electron microscopy. It is shown that already the very first formed polymer changes disturb the bicontinuous phase structure and nucleate a vesicular phase; with further consumption of the monomer mixture, at least three other phase transitions can be detected, ending with a simple globular surfactant structure.Although direct templating of the original mesomorphous structure does not occur, the existence of the diverse lyotropic phases influences the final structure. It is shown that simple dilution changes the characteristic length of the network elements from about 2 m down to 50 nm. This is explained by a combination of a nucleation-and-growth mechanism with the influence of a restricted colloidal stability in anisometric lyotropic phases.     

Formation of fractal porous silica by hydrolysis of TEOS in a bicontinuous microemulsion

Mesoporous silica particles have been prepared by hydrolysis of TEOS (Si(OC₂H₅)₄) in bicontinuous microemulsions containing polyoxyethylene (POE) dodecylether, isooctane and water. TEOS was dissolved in a continuous water phase and hydrolyzed by the dispersed water at around the phase inversion temperature (60°C). Undulating solid materials with layered mesostructures were produced from middle-phase microemulsions in the three phase region (o/w=0.2–0.7). On the other hand, the solids obtained from the lower aqueous phase in the three phase region were found to have a heterogeneous disordered structure. Measurements of the fractal dimensions were performed in the macropore region using a box-counting method for the outline of the SEM texture. We found that the macropore size distribution in the particles prepared from the middle-phase microemulsion follows the fractal rule with a dimension of 1.7. From the results of nitrogen adsorption/desorption curves on the silica, a steep increase in the adsorption amounts was observed at a relative pressure below 0.2, and adsorption/desorption hysteresis was also observed at a relative pressure between 0.3 and 0.5. These studies suggest that the silica synthesized in the bicontinuous microemulsion mesostructure has a very broad size range from micro to macropores with a fractal distribution.     

Hollow-fiber membranes coated with polymerizable bicontinuous microemulsions

A new method has been successfully employed to prepare hollow-fiber membranes by coating and polymerizing bicontinuous microemulsions onto the internal surfaces of hollow-fiber membranes. The bicontinuous microemulsion consisting of water, a polymerizable zwitterionic surfactant of acryloyloxyundecyl dimethylammonio acetate, methyl methacrylate, and 2-hydroxylethyl methacrylate (HEMA) can form a transparent polymer thin film after polymerization. The hollow-fiber membranes as the supports for microemulsion coatings were fabricated from the spinning solution of polyethersulfone/diethylene glycol/N-methyl-2-pyrrolidone. The microemulsion coated hollow-fiber membranes were evaluated by the separation efficiency and the permeation rate of polyethylene glycol (PEG) solutions. The performance of coated membrane on the PEG separation is strongly dependent on the concentration of HEMA and water in precursor bicontinuous microemulsions. The pore size of the hollow-fiber membranes can be regulated between about 2 to 40 nm by varying the composition of precursor bicontinuous microemulsions. The characteristics of the coated membranes is believed to be directly related to the bicontinuous structures of precursor bicontinuous microemulsions. The use of polymerizable bicontinuous microemulsions enable one to better control the microstructures of coated membranes via in situ polymerization.     

微乳液催化苯乙烯聚合反应

微乳液催化苯乙烯聚合反应１）郝京诚汪汉卿２）（中国科学院兰州化学物理研究所兰州７３００００）石元昌李干佐（山东大学胶体与界面化学研究所济南２５０１００）关键词微乳液催化苯乙烯聚合微乳液［１］是油、水、表面活性剂和助表面活性剂在适当比例下自发形成的热力...     

PHASE BEHAVIOUR IN THE SYSTEM TRS 10-80/BUTANOL/PETROL D/SODIUM CHLORIDE

The phase diagrams for the system TRS 10-80/ butanol/Petrol D/sodium chloride show that the weight ratio B = TRS/butanol is very important for the stability of the microemulsion. R = 1 results in a very limited microemulsion region. Provided the ratio is >1.22 the minimum amount of (TRS+butanol) necessary to form a microemulsion, with equal amounts of water and Petrol D, is 15% and approximately independent of R.However, as R is increased the solubility of water in the (TRS+butanol) mixture is reduced and a liquid crystalline phase is formed. Its presence increases the viscosity and the kinetic stability of the emulsions formed at low content of Petrol D.

Addition of electrolyte reduces the minimum amount of (TRS+butanol) necessary to form a microemulsion. Furthermore, systems rich in water separate into two phases; an upper microemulsion phase and a lower aqueous phase. This can be explained in terms of a redistribution of the butanol from the aqueous phase to the oil phase. It is shown that, although the studied system contains unpurified technical products, the phase behaviour is very similar to that of model systems of pure chemicals.

X-ray diffraction showed that the liquid crystal line phase was lamellar. The thickness of the amphiphilie layer was 26-28 Å. It is more difficult to obtain direct information of the structure of the microemulsion. However, conductivity data indicated a “bicontinuous” structure or at least, the occurrence of highly dynamic aggregates over a large concentration range.     

Surfactant-free oil/water and bicontinuous microemulsion composed of benzene, ethanol and water

<正>Generally,a microemulsion consists of oil,water,surfactant and sometimes cosurfactant.Herein,we report a novel suffactant-free microemulsion(denoted as SFME) composed of benzene,water and ethanol without the amphiphilic molecular structure of traditional surfactant.The phase behavior of the ternary system was investigated,finding that there were a single-phase region and a two-phase region in ternary phase diagram.The electrical conductivity measurement was employed to investigate the microregion of the single-phase region,and a bicontinuous microregion and a benzene-in-water(O/W) microemulsion microregion were identified,which was confirmed by freeze-fracture transmission electron microscopy(FF-TEM) observations.The sizes of the microemulsion droplets are in the range of 20-50 nm.     

Formulation and physicochemical properties of promising avermectin microemulsion with biodegradable surfactant and oil

Green microemulsion suitable for oil-soluble pesticide delivery has been prepared using butyl acetate as oil phase, alkyl polyglycoside (APG) and linear alkylbenzene sulfonate (LAS) as mixed surfactant, and short-chain alcohol as cosurfactant. Pseudoternary phase diagrams were constructed to investigate the effects of APG and LAS mixing ratio, the chain length of the cosurfactant on the microemulsion phase behavior. A fully dilutable region run through the phase diagram can be observed and the structure of the microemulsion transformed from water-in-oil, bicontinuous to oil-in-water along with the addition of water according to the result of conductivity measurement. Based on the phase diagram, the avermectin microemulsion formulations were chosen from the fully dilutable line with the minimum surfactant-to-oil ratio. Dilution stability of the microemulsion with hard water was studied by dynamic light scattering (DLS), the microemulsion can maintain the uniform and homogeneous appearance although the droplet size increased after dilution. The diluted microemulsion were also studied by dynamic surface tension and dynamic contact angle, and the excellent wetting and spreading properties on hydrophobic surface was demonstrated.     

Oil/water droplet formation by temperature change in the water/c(16)e(6)/mineral oil system

Droplet sizes of oil/water (O/W) nanoemulsions prepared by the phase inversion temperature (PIT) method, in the water/C16E6/mineral oil system, have been compared with those given by a theoretical droplet model, which predicts a minimum droplet size. The results show that, when the phase inversion was started from either a single-phase microemulsion (D) or a two-phase W+D equilibrium, the resulting droplet sizes were close to those predicted by the model, whereas, when emulsification was started from W+D+O or from W+D+Lalpha (Lalpha = lamellar liquid crystal) equilibria, the difference between the measured and predicted values was much higher. The structural changes produced during the phase inversion process have been investigated by the 1H-PFGSE-NMR technique, monitoring the self-diffusion coefficients for each component as a function of temperature. The results have confirmed the transition from a bicontinuous D microemulsion at the hydrophile-lipophile balance (HLB) temperature to oil nanodroplet dispersion in water when it is cooled to lower temperatures.     

Improved solubilization of Celecoxib in U-type nonionic microemulsions and their structural transitions with progressive aqueous dilution

Celecoxib (clxb) is an important drug for treatment of rheumatoid arthritis and osteoarthritis by specifically inhibiting the enzyme cyclooxygenase-2 (COX-2). Clxb is a type 2 drug characterized by low water solubility (<5 mug/ml) and fast transmembrane transport. The present formulations require high dosage since the transmembrane transport fluctuates and is very difficult to control. Dissolving the drug within an oil phase was not practical since its dissolution was very small and its dispersion in water was impossible. In our recent studies, we learned to construct U-type phase diagrams and to formulate reverse microemulsions (oil-based concentrates) that are progressively and fully dilutable with aqueous phase. In the present study, we solubilized clxb in nanostructures of reverse micelles of U-type nonionic microemulsions that consisted of R(+)-limonene, alcohol, propylene glycol (PG), and hydrophilic surfactant (Tween 60). The solubilization capacity of the drug in these systems is many times higher than in either the oil or the aqueous phase. The clxb solubilized microemulsions are fully diluted with aqueous phase without phase separation. The solubilization capacity decreases as the water content increases. Electrical conductivity, viscosity, and self-diffusion (SD) coefficients of the microemulsion components were measured along a suitable water dilution line. The three major microemulsion regions were detected and the transitions between the W/O to bicontinuous phase and from this phase to the O/W droplets were identified (at 30 and 70 wt% aqueous phase, respectively). From the SD coefficients, it was found that the drug is initially solubilized at the interface of the W/O droplets and there are no significant structural changes. The transition to a bicontinuous phase occurs at the same water content as in the empty (i.e., without drug) system. From the viscosity profiles, we concluded that the drug affects the structure of the bicontinuous phase as reflected in the water content at which the oil-continuous network is destroyed and full inversion occurs (50 vs 55 wt% in the drug-loaded system). Upon further dilution the drug remains solubilized at the interface and is oriented with its hydrophilic part facing the water, and is strongly affects the inversion to O/W droplets. From Small Angle X-ray Scattering (SAXS) measurements we learned that the drug effects the structure of microemulsion droplets and forms "ill-defined structures," probably less spherical. Yet, the overall droplet sizes at the high dilutions did not change very much.     

Synthesis and Characterization of Hydrogel Nanoparticles Through Inverse Microemulsion Polymerization of 2-Acrylamido-2-methyl-1-propanesulfonic Acid

Nanosized hydrogel particles prepared through inverse microemulsion polymerization of 2-acrylamido-2-methyl-1-propanesulfonic acid, using the combination of an oil soluble emulsifier (SPAN80) with a water soluble emulsifier (TWEEN 80), and precise determination of HLB range related to the formation of stable single phase microemulsions.

The effect of crosslink density, water phase to oil phase ratio, and the hydrophilic-lipophilic balance (HLB) value on polymerization rate, particle size, and swelling ratio were investigated. It found that polymerization rate and particle size are strongly dependent on the water phase to oil phase ratio. Hydrogel samples prepared using oil soluble and water soluble initiators and the results showed that the initiator type had a great influence on monomer conversion and particle size. Effect of pH on equilibrium swelling of hydrogels was studied by dynamic light scattering and hydrogels showed pH-independent swelling behavior in a broad range of pH values. We also reported and discussed the crosslink density distribution in nanogels prepared by inverse microemulsion polymerization.