Preparation of waterborne dispersions of epoxy resin by the phase-inversion emulsification technique. 2. Theoretical consideration of the phase-inversion process

 A theoretical consideration of the phase-inversion technique to prepare waterborne particles based on the experimental facts of the phase inversion process given in part 1 of this series is presented. The deformation and breakup of the water droplets dispersed in an epoxy resin phase under shear action are analyzed in terms of microrheology. The interaction and coalescence dynamics among the water droplets stabilized by an interfacial layer formed by the emulsifier molecules are discussed in terms of Derjaguin–Landau–Verwey–Overbeek theory and effective collision theory, respectively. A criterion for the completion of phase-inversion is that the attraction among the water droplets exceeds the entropic repulsion. Thus, a physical model of phase-inversion is proposed to predict the effects of some control variables on the phase-inversion process as well as the structural features of the waterborne particles, by which the experimental results could be well interpreted. It is indicated that the achievement of phase inversion is determined by the dynamic coalescence among the water droplets before the phase-inversion point (PIP). If the dynamic coalescence among the water droplets is ignored, phase inversion is achieved completely and sub- micron-sized particles are prepared. In comparison, if the dynamic coalescence is significant, phase inversion is achieved incompletely and a large complex water-in-oil-in-water structure is prepared. In the case of complete phase inversion, it is shown that the size of the waterborne particles is comparable with the size of the water droplets before the PIP. Received: 15 March 2000/Accepted: 16 May 2000     

环氧树脂相反转乳化过程相态发展研究

以扫描电镜为主要手段,观察了环氧树脂相反转乳化过程中的相态演化过程.结果表明:在较高乳化剂浓度下,当水含量达到某一临界值时,原W/O体系中水滴间的相互吸引大于水滴间的排斥作用,导致相邻水滴同时快速地融合为连续相并得到水基微粒,水基微粒的尺寸较小,约为亚微米级,尺寸分布窄,微粒为单个粒子.在乳化剂浓度较低情况下,非相邻较大水滴在剪切场作用下随机地融合为连续相,发生不完全相反转,并得到W/O/W结构,水基微粒尺寸较大,约10微米数量级,尺寸分布宽且为一种复合多孔结构.此外,分析了相反转发展演变过程.     

环氧树脂相反转乳化过程相态发展研究＊

以扫描电镜为主要手段,观察了环氧树脂相反转乳化过程中的相态演化过程.结果表明 在较高乳化剂浓度下, 当水含量达到某一临界值时, 原W/O体系中水滴间的相互吸引大于水滴间的排斥作用, 导致相邻水滴同时快速地融合为连续相并得到水基微粒, 水基微粒的尺寸较小, 约为亚微米级, 尺寸分布窄,微粒为单个粒子.在乳化剂浓度较低情况下,非相邻较大水滴在剪切场作用下随机地融合为连续相,发生不完全相反转, 并得到W/O/W 结构, 水基微粒尺寸较大,约10微米数量级,尺寸分布宽且为一种复合多孔结构.此外,分析了相反转发展演变过程.     

不完全相反转乳化过程分散相水滴形态发展研究

相反转乳化技术是制备高分子树脂水基分散体系的新方法[1～4].相反转指多组分体系(如油/水/乳化剂)中的连续相在一定条件下相互转化的过程,如在油/水/乳化剂体系中,其连续相由水相向油相(或从油相变为水相)的转变.在连续相转变区,体系的界面张力最低,因而分散相的尺寸最小.同理,可利用相反转技术直接将高分子树脂乳化为尺寸很小的水基微粒,即制备高分子树脂的水基分散体系.由于高分子树脂的粘弹性及相反转过程的复杂性,对高分子树脂的相反转乳化过程的机理研究较少.杨振忠[5]等通过调节高分子非离子型乳化剂浓度,可以有效地控制相反转完善程…     

PREPARATION OF BISPHENOL A EPOXY RESIN WATERBORNE DISPERSIONS BY THE PHASE INVERSION EMULSIFICATION TECHNIQUE*

The phase inversion emulsification technique (PIET) is an effective physical method for preparing waterbornedispersions of polymer resins. Some results concerning the preparation of bisphenol A epoxy resin waterborne dispersions byPIET in our laboratory were summarized. Electrical properties, rheological behavior and morphological evolution duringphase inversion progress were systematically characterized. The effects of the emulsifier concentration and emulsificationtemperature on phase inversion progress and the structural features of the waterborne particles were studied as well. Thedeformation and break up of water drops in a shear field were analyzed in terms of micro-rheology, while the interaction andcoalescence dynamics of water drops were discussed in terms of DLVO theory and Smoluchowski effective collision theory,respectively. Based on the experimental results and theoretical analysis, a physical model of phase inversion progress wassuggested, by which the effects of the parameters on phase inversion progress and the structural features of the waterborneparticles were interpreted and predicted.     

环氧树脂水基分散体系的相反转乳化

以聚乙二醇－邻苯二甲酸酐－环氧树脂Ｅ－４４多元嵌段共聚体为乳化剂,将环氧树脂Ｅ－４乳化成水包油的稳定水基乳液。用乳液体系电导率和粘度的变化表征了相反转乳化过程。研究了乳化剂浓度、三元多嵌段共聚体中亲水嵌段分子量和乳化温度对相反转乳化过程的影响。实验结果表明,体系在较高乳化剂浓度（９．１％）下为完全相反转,在低乳化剂浓度（４．１％）下为不完全相反转。相反转时水与环氧树脂Ｅ－４４的重量比值随乳化剂浓度     

乳化剂分子亲水组分含量对相反转乳化过程的影响

高分子树脂水基分散体系 ,因其结构的可灵活调节性 ,在许多方面得到应用 ,又因其不含有机溶剂 ,能完全满足环境保护和生态的要求而备受关注 [1～ 3] .相反转乳化技术是制备高分子水基体系的新方法 ,它适用于制备包括加聚物和缩聚物的大多数高分子水基体系 ,大大拓宽了水基体系的范围 [4 ] .杨振忠等[5] 利用自己合成的高分子非离子型乳化剂将环氧树脂乳化成微粒尺寸小且分布窄的水基分散体系 ,对相反转机理和相反转技术进行了深入研究 .研究表明 ,乳化剂浓度和乳化温度对相反转后水基微粒尺寸和形态有重要影响 ,高乳化剂浓度和较低的乳化温…     

不完全相反转发展过程的流变行为

以动态应力流变仪ＤＳＲ（ＤｙｎａｍｉｃＳｔｒｅｓＲｈｅｏｍｅｔｅｒ）对双酚Ａ型环氧树脂在低乳化剂浓度（２３３ｗｔ％）下的相反转乳化过程进行了稳态应力扫描及动态频率扫描实验．实验结果表明,体系在相反转点前表现为牛顿流体行为,粘度几乎不变;相反转点时,体系粘度增加幅度很小,体系的有关动态流变参数（剪切储能模量、损耗模量和复数粘度）均出现极小值,将此归于局部连续水相的润滑作用;进一步加水,体系的动态流变量增加,意味着相反转在相反转点后仍在继续进行．所以,体系在低乳化剂浓度时,发生了不完全相反转．     

Mechanistic investigation on the formation of epoxy resin multi‐hollow spheres prepared by a phase inversion emulsification technique

Micrometer sized multi‐hollow spheres of epoxy resin were prepared by a physical method so‐called phase inversion emulsification technique. The formation mechanism of the titled spheres was studied by incomplete phase inversion. The requisite for the formation of multi‐hollow spheres was that irreversible coalescence among the water droplets under shear action before the phase inversion point existed. This process could be facilitated by a lower emulsifier concentration and a higher emulsification temperature. Moreover, a theoretical explanation of the formation of the titled spheres was presented.     

相反转技术制备环氧树脂水基体系——相反转过程的流变行为研究

对高乳化剂浓度下的相反转发展过程的流变行为进行了应力扫描、动态频率扫描实验表征．结果表明，乳化剂浓度较高时，体系发生完全相反转；体系在相反转点前为Ｗ／Ｏ结构，其粘度几乎不随剪切应力的改变而改变，表现为牛顿流体行为；体系在相反转点后为Ｏ／Ｗ结构，具有很高的粘弹性，并且在较高剪切应力下表现为典型的假塑性．这是由于高分子水基微粒间通过其表面覆盖的表面活性剂与水形成氢键而产生了一种静态结构，此结构在较高剪切应力作用下破坏而导致假塑性．     

Factors Affecting the Phase-Inversion Temperature of Fatty Alcohol Ethoxylates

Factors that affect the phase-inversion temperature (PIT) based on nonionic surfactant fatty alcohol ethoxylates were investigated. Phase-inversion process was continuously monitored by determining changes in conductivity with temperature. The influences of oil-to-water ratio, emulsifier concentration, emulsifier mixing ratio, sodium chloride, and oil types on the PIT of emulsions were investigated. Results showed that the PIT of the emulsions declined with increased oil-to-water ratio. Emulsifier concentration significantly affected the PIT temperature. High sodium chloride content suppressed phase inversion. A lower Brij72-to-Brij721 ratio corresponded to higher PIT. Different oils required different HLB numbers in the phase-inversion process.     

无皂相反转乳化法制备高分子水基分散体系

高分子树脂水基分散体系是指高分子树脂以微粒形式分散于水中 ,包括高分子乳液、高分子悬浮液等体系 .由于高分子树脂水基分散体系具有低成本 ,高性能 ,无污染等优点 ,一直受到普遍关注 .高分子树脂乳液一般通过乳液聚合制备 .该方法只适用于由含双键的单体制备的加聚产物 .而在制备缩聚产物的乳液时 ,乳液聚合方法局限性很大 ,而最近发展起来的相反转乳化技术 ,适用于制备包括加聚产物和缩聚产物在内的大多数高分子水基分散体系 ,拓宽了高聚物水基分散体系的范围 [1] .杨振忠等 [2～ 5] 利用相反转乳化技术制备了未固化和可固化的环氧树脂…     

高分子水基微粒形态与界面膜性质的关系

高分子水基微粒形态与界面膜性质的关系杨振忠赵得禄许元泽徐懋（中国科学院化学研究所高分子物理开放实验室北京１０００８０）关键词高分子树脂，相反转，水基微粒，界面膜相反转技术是制备高分子树脂微粒化水基化体系的新方法［１］，正成为高分子技术的一个热门方向...     

Convenient synthesis of novel fluorinated polyurethane hybrid latexes and core-shell structures via emulsion polymerization process with self-emulsification of polyurethane

Novel fluorinated polyurethane hybrid latexes in the size range of 40–50 nm, fluoroalkyl acrylate as fluorinated monomers, with various fluorine content (F% = 9∼26 wt%) were successfully prepared via emulsion polymerization process without traditional emulsifier. The waterborne polyurethane, which was synthesized by using isophronediisocyanate, dimethylol propionic acid, polyethylene glycols, etc., served not only as copolymerizable macromonomer but also as polymeric high molecular weight emulsifier. The structures of polyurethane macromonomer and fluorinated polyurethane were characterized by Fourier transform infrared and H¹-NMR. Particle size, zeta potential, micromorphology of the latex par.ticles, and surface properties were investigated by dynamic light scattering, potential particle size analyzer, transmission electron microscopy, and contact angle measurement, respectively. Results illustrated that the advantage of this process is that the size of fluorinated polyurethane hybrid particle is less sensitive to the composition. Furthermore, it was showed that fluorinated polyurethane latex particles had core-shell structures, especially when the content of fluorine was 26.08 wt%. Moreover, there was an obvious migration of fluorinated groups to the surface during the formation of fluorinated polymer films, although fluorinated groups were covered by polyurethane in latex particles.     

Sub‐Micron‐Sized Waterborne Particles of Crosslinked Epoxy Resin Prepared by Phase‐Inversion Emulsification

Sub‐micron waterborne dispersions of crosslinked bisphenol A epoxy resin were prepared by a phase‐inversion emulsification process in the presence of N,N‐dimethylbenzylamine as the curing agent. Differential scanning calorimetry was used to monitor the extent of crosslinking by post‐polymerization. The time and temperature of post‐polymerization influence the extent of crosslinking. Particle size could be controlled in the range 100–300 nm with a narrow size distribution by varying the content of curing agent and polymeric emulsifier, as investigated by means of scanning electron microscopy. A tentative physical model of the phase‐inversion emulsification process in the presence of curing agent is proposed.     

相反转乳化技术制备环氧树脂交联多孔微球

多孔微球在分离吸附、催化、涂料印刷等多方面具有潜在应用价值 .最近研究表明 ,当微孔孔径在 2 0 0～ 80 0ｎｍ范围时 ,由于强烈的光散射作用 ,多孔微球可以作为遮光剂使用[1] .Ｏｋｕｂｏ等用酸碱逐步处理法制备了一些共聚物的亚微米级多孔球[2～ 4] .Ｏｋｕｂｏ又用动态溶胀种子聚合法制备了微米级的聚合物微球 ,用类似的方法得到了多孔结构[5,6] .但这种方法涉及了许多烦琐过程并且产生了很多副产物需要处理 ,使得其费时费力而且成本相当高 .Ｓｃｈｌａｒｂ等发展了一种新的制备方法 ,在乳液聚合过程中引入有机溶剂 ,在实验后期除掉有机…     

Micron-sized monodispersed polymer particles produced by seeded polymerization for the dispersion of high swelling of polymer particles with a large amount of monomer

 Micron-sized monodispersed polystyrene (PS)/poly(n-butyl methacrylate) composite particles were produced as follows. First, 1.77 μm-sized monodispersed PS seed particles produced by dispersion polymerization were dispersed in ethanol/water (1/2, w/w) medium dissolving poly(vinyl alcohol) as a stabilizer. n-Butyl methacrylate (BMA) monomer dissolving benzoyl peroxide initiator was emulsified in ethanol/water (1/2, w/w) solution of sodium dodecyl sulfate as emulsifier with ultrasonic homogenizer, and the BMA monomer emulsion was mixed with the PS seed emulsion. The PS seed particles absorbed with a large amount of BMA (about 150 times weight of the seed particles) for 2 h to about 10 μm in diameter while keeping good monodispersity and BMA droplets disappeared finally. The seeded polymerization was carried out at 70 °C after a certain amount of water was added to depress the redissolving of BMA from the swollen particles into the medium by raising from room temperature to the polymerzation temperature. Received: 21 February 1996 Accepted: 4 September 1996     

Phase transitions and microstructure of emulsion systems prepared with acylglycerols/zinc stearate emulsifier

The emulsification processes, during which acylglycerols/zinc stearate emulsifier, water, and oil phase formed ternary systems, such as water-in-oil (W/O) emulsions, oil-in-water (O/W) dispersions, and unstable oil-water mixtures, were investigated in order to characterize the progressive transformations of the dispersed systems. The type, structure, and phase transitions of the systems were found to be determined by temperature and water phase content. Crystallization of the emulsifier caused the destabilization and subsequent phase inversion of the emulsions studied, at a temperature of 60-61 degrees C. The observed destabilization was temporary and led, at lower temperature, to W/O emulsions, "O/W + O" systems, or O/W dispersions, depending on the water content. Simultaneous emulsification and cooling of 20-50 wt % water systems resulted in the formation of stable W/O emulsions that contained a number of large water droplets with dispersed oil globules inside them ("W/O + O/W/O"). In water-rich systems (60-80 wt % of water), crystallization of the emulsifier was found to influence the formation of crystalline vesicle structures that coexisted, in the external water phase, with globules of crystallized oil phase. Results of calorimetric, rheological, and light scattering experiments, for the O/W dispersions obtained, indicate the possible transition of a monostearoylglycerol-based alpha-crystalline gel phase to a coagel state, in these multicomponent systems.     

体系pH值、乳化温度和电解质离子对异丙甲草胺水乳剂稳定性的影响

通过测定药物液滴的平均粒径和Zeta电位研究了体系pH值、 乳化温度和电解质离子对乳化剂三苯乙烯基苯酚聚氧乙烯醚磷酸酯三乙醇胺盐(SCP)稳定的异丙甲草胺水乳剂稳定性的影响. 结果发现, 体系的pH值影响SCP分子在水中的电离能力, 当pH=9时, SCP完全电离, 能为液滴提供较大的静电稳定作用, 水乳剂稳定性最好; 乳化温度低时, SCP分子向液滴界面扩散慢, 且舒展不完全, 液滴所带负电荷较少, 水乳剂稳定性差; 温度升高后, 水相黏度减小, 布朗运动加剧, 液滴碰撞合并几率增大, 且SCP分子热运动增强, 易从界面逃逸, 液滴间静电斥力减弱, 同时SCP亲水性下降, 水乳剂稳定性变差; 电解质离子会压缩界面双电层, 降低Zeta电位, 液滴带电量减少而聚结, 离子浓度越大, 电荷数越大, 水乳剂稳定性越差. 在相同的离子浓度下, 水合半径小的Ca²⁺压缩双电层能力强于Mg²⁺, 添加Ca²⁺后水乳剂稳定性更差.     

Microemulsion polymerization of styrene using a polymerizable nonionic surfactant and a cationic surfactant

High polymer/surfactant weight ratios (up to about 15:1) of polystyrene microlatexes have been successfully produced by microemulsion polymerization using a small amount of polymerizable surfactant, ω-methoxypoly(ethylene oxide)₄₀ undecyl α-methacrylate macromonomer (PEO-R-MA-40), and cetyltrimethylammonium bromide (CTAB). After generating “seeding particles” in a ternary microemulsion containing only 0.2 wt% CTAB and 0.1 wt% styrene, the additional styrene containing less than 1 wt% PEO-R-MA-40 was added dropwise to the polymerized microemulsion for a period of about 4 h at room temperature. PEO-R-MA-40 copolymerized readily with styrene. The stable microlatexes were bluish-transparent at a lower polymer content and became bluish-opaque at a higher polymer content. Nearly monodisperse latex particles with diameters ranging from 50 to 80 nm and their molar masses ranging from 0.6 to 1.6 × 10⁶ g/mol could be obtained by varying the polymerization conditions. The dependence of the number of particles per milliliter of microlatex, the latex particle size and the copolymer molar mass on the polymerization time is discussed in conjunction with the effect of the macromonomer concentration. Received: 25 October/2000 Accepted: 2 February 2001