反相乳液共聚合制备两性丙烯酰胺共聚物的研究

采用Span80-Tween80复合乳化剂和AIBA引发剂,进行丙烯酸钠(NaAA)/丙烯酰胺(AM)/丙烯酰氧基乙基三甲基氯化铵(DAC)反相乳液共聚合.研究了聚合温度、引发剂用量、单体浓度、共聚单体中DAC和AM含量、乳化剂用量及其HLB值、水/油比和水相pH值等聚合反应工艺条件或参数对聚合反应单体转化率和聚合物特性粘度的影响,聚合物特性粘度随引发剂用量和单体浓度的增大而增大的实验结果证实了该两性丙烯酰胺共聚物反相乳液制备过程中凝胶效应的存在.傅立叶红外光谱组成分析表明了两性丙烯酰胺共聚物的成功合成,扫描电镜观测乳胶粒粒径范围在0.6~8.0μm.     

Poly(acrylamide-co-2-acrylamido-2-methyl-1-propanesulfonic Acid) Nanogels made by Inverse Microemulsion Polymerization

Poly(acrylamide-co-2-acrylamido-2-methyl-1-propanesulfonic acid) poly(AM-co-AMPSA) nanogels were prepared through inverse microemulsion polymerization with low AMPSA/AM weight ratio in the feed (up to 0.3357) to control particle size and pH sensitivity. An aqueous solution of AM and AMPSA was used as the dispersed phase for microemulsion with sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/Toluene solution as the dispersion medium. The polymerization was carried out at 50°C in the presence of 2,2-azobisisobutyronitrile (AIBN) and N,N′-methylenebisacrylamide (NMBA) as an initiator and a crosslinker, respectively. Fourier transform infra red spectrophotometer (FTIR) and ¹H-nuclear magnetic resonance spectroscopy (¹H-NMR) studies confirm the occurrence of copolymerization between the two monomers. The hydrodynamic diameter of synthesized poly(AM-co-AMPSA) nanogels is found to be in the range of 63–125nm as measured by dynamic light scattering (DLS). The equilibrium swelling and the effect of pH on particle size of copolymer nanogel are found to depend on the copolymer composition. The polymer chain composition, thermal properties and morphology of nanogels were measured by elemental analysis, thermogravimetric analyzer (TGA) and differential scanning calorimeter (DSC), and scanning electron microscope (SEM), respectively.     

Microemulsion polymerization of butyl acrylate. IV. Effect of emulsifier concentration

The oil/water microemulsion polymerizations of butyl acrylate initiated by a water (ammonium peroxodisulfate, APS) or oil (dibenzoyl peroxide, DBP) soluble radical initiator at different emulsifier concentrations were investigated. The rate of polymerization vs. conversion curve shows two intervals. The rate of polymerization is found to decrease with the emulsifier concentration. This finding was discussed in terms of the decrease of both radical and monomer concentration, the chain transfer to emulsifier, desorption of chaintransferred radicals, and the contribution of solution polymerization. The polymerization is faster with APS. In the APS system the rate per particle or the number of radicals per particle increases exponentially with increasing particle size. The particle size and number increase during the whole polymerization. This behavior was discussed in terms of the nucleation of monomer-containing micelles and agglomeration of primary particles during the whole polymerization. © 1995 John Wiley & Sons, Inc.     

Polymerization of acrylamide in nonionic microemulsions: Characterization of the microlatices and polymers formed

Free radical polymerization of acrylamide was carried out in nonionic microemulsions of water, an isoparaffinic oil, Isopar M and a blend of nonionic emulsifiers: a sorbitan sesquioleate and a polyoxyethylene sorbitol hexaoleate (HLB of the mixture: 9.3). The size and the stability of the latex particles formed after polymerization were studied as a function of monomer, emulsifier and electrolyte concentration. High emulsifier and high monomer contents favor obtaining high molecular weight polyacrylamides. It is shown that both the number of polymer chains contained in each latex particle and the size of the particles are essentially controlled by the acrylamide/emulsifier weight ratio.     

(2-甲基丙烯酰氧乙基)三甲基氯化铵-丙烯酰胺反相微乳液共聚合特性研究

选用SPAN80与OP10复合乳化剂、K₂S₂O₈-Na₂SO₃氧化还原引发剂,进行(2-甲基丙烯酰氧乙基)三甲基氯化铵-丙烯酰胺反相微乳液共聚合反应.研究了单体配比、电解质浓度和乳化体系的油水比对共聚物分子量及离子度的影响,考察了该共聚合体系的反应特性.     

Microemulsion polymerization of styrene in the presence of a cationic emulsifier

The principal subject discussed in the current paper is the radical polymerization of styrene in the three- and four component microemulsions stabilized by a cationic emulsifier. Polymerization in the o/w microemulsion is a new polymerization technique which allows to prepare the polymer latexes with the very high particle interface area and narrow particle size distribution. Polymers formed are very large with a very broad molecular weight distribution. In emulsion and microemulsion polymerizations, the reaction takes place in a large number of isolated loci dispersed in the continuous aqueous phase. However, in spite of the similarities between emulsion and microemulsion polymerization, there are large differences caused by the much larger amount of emulsifier in the latter process. In the emulsion polymerization there are three rate intervals. In the microemulsion polymerization only two reaction rate intervals are commonly detected: first, the polymerization rate increases rapidly with the reaction time and then decreases steadily. Essential features of microemulsion polymerization are as follows: (1) polymerization proceeds under non-stationary state conditions; (2) size and particle concentration increases throughout the course of polymerization; (3) chain-transfer to monomer/exit of transferred monomeric radical/radical re-entry events are operative; and (4) molecular weight is independent of conversion and distribution of resulting polymer is very broad. The number of microdroplets or monomer-starved micelles at higher conversion is high and they persist throughout the reaction. The high emulsifier/water ratio ensures that the emulsifier is undissociated and can penetrate into the microdroplets. The presence of a large amount of emulsifier strongly influences the reaction kinetics and the particle nucleation. The mixed mode particle nucleation is assumed to govern the polymerization process. At low emulsifier concentration the micellar nucleation is dominant while at a high emulsifier concentration the interaction-like homogeneous nucleation is operative. Furthermore, the paper is focused on the initiation and nucleation mechanisms, location of initiation locus, and growth and deactivation of latex particles. Furthermore, the relationship between kinetic and molecular weight parameters of the microemulsion polymerization process and colloidal (water/particle interface) parameters is discussed. In particular, we follow the effect of initiator and emulsifier type and concentration on the polymerization process. Besides, the effects of monomer concentration and additives are also evaluated.     

Preparation of metal nanoparticles in water-in-oil (w/o) microemulsions

The use of an inorganic phase in water-in-oil microemulsions has received considerable attention for preparing metal particles. This is a new technique, which allows preparation of ultrafine metal particles within the size range 5 nm相似文献   

粒径可控阳离子型聚苯乙烯纳米粒子的制备及表征

在采用阳离子型双子（gemini）表面活性剂作为乳化剂,不使用任何助乳化剂的条件下,通过改进微乳液聚合工艺制备了窄分布粒径可控的阳离子型聚苯乙烯（PS）纳米乳液。 改进微乳液聚合的主要特点是：大部分苯乙烯以预乳液的形式恒速滴入引发聚合的微乳液中,使用具有高乳化性能的gemini表面活性剂作为乳化剂能明显降低乳胶粒粒径。 实验结果表明,少量阳离子单体三甲基烯丙基氯化铵作为共聚单体能够明显减小Z均粒径、降低粒度分布,乳化剂用量、引发剂用量和反应温度均能影响制备乳胶粒的粒径及其粒度分布。 乳化剂和引发剂用量分别为苯乙烯质量的5%~10%和1.0%~1.5%、反应温度为70~75 ℃时,能够制备粒径小分布窄的阳离子型聚苯乙烯纳米粒子。 Z均粒径与苯乙烯质量之间的线性关系表明,Z均粒径可以通过苯乙烯用量来控制。 不同聚合工艺下制备的聚合物粒度分布曲线表明,改进微乳液聚合工艺（半连续预乳化工艺）在制备窄分布的聚合物纳米粒子方面具有很强的优越性。     

含氨基、羟基丙烯酸乳液聚合的稳定性

采用间歇及半连续乳液聚合方式,以过硫酸铵/亚硫酸钠为引发体系,合成了甲基丙烯酸甲酯/丙烯酸丁酯/甲基丙烯酸羟乙酯/甲基丙烯酸二氨基乙酯四元共聚物胶乳.系统研究了乳化剂种类和浓度、聚合温度、乳化单体进料方式及进料速率对聚合过程稳定性的影响.聚合温度降低,乳化单体进料速度减慢有利于聚合过程的稳定,采用种子半连续聚合方式比间歇聚合过程更稳定,乳化剂浓度的增加有利于聚合稳定性的提高和乳胶粒子的均匀化.     

Modeling inverse microemulsion polymerization

A mathematical model for inverse microemulsion polymerization has been developed. The model has been used to fit experimental results of the effect of initiator concentration, light intensity, emulsifier concentration, and dispersed phase weight fraction on the monomer conversion evolution, particle size, and polymer molecular weight in the inverse microemulsion polymerization of 2-methacryloyl oxyethyl trimethyl ammonium chloride (MADQUAT) initiated by UV light in the presence of AIBN. A good fitting of the experimental data was achieved. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2167–2178, 1999     

Microstructured Polyacrylamide Hydrogels Prepared Via Inverse Microemulsion Polymerization

The synthesis by a two-stage polymerization process of microstructured polyacrylamide hydrogels with large swelling capacity and improved mechanical properties is reported. First, crosslinked polyacrylamide particles of nanosize scale are made by inverse microemulsion polymerization. These particles are then dried and redispersed in an aqueous solution of acrylamide and polymerized in the presence of a crosslinking agent. The microstructured hydrogels, in contrast to transparent conventional polyacrylamide hydrogels, are translucid due to the presence of the dispersed particles. The swelling capacity of these hydrogels increases as the particle content increases and their Young and elastic moduli (at equilibrium swelling) diminish only slightly. Mechanical tests disclose that the microstructured hydrogels have larger Young moduli than conventional hydrogels with an identical degree of swelling. Copyright 2001 Academic Press.     

Microemulsion Polymerization of Methyl Methacrylat

The microemulsion polymerization of methyl methacrylate was studied. The effects of feeding modes on the structure and the properties of the obtained polymer microlatex were investigated by measuring the conversion, the transmittance and the refractive index of the latex, and by measuring the particle size, the molecular weight and the glass transition temperature (Tg) of the polymers. The results show that compared to the batch feeding mode, the semi-continuous feeding mode is more favorable to form a PMMA microlatex with a higher transmittance, a smaller particle size, a higher molecular weight and a higher Tg. And the obtained PMMA microlatex has a 30 %-40 % (mass fraction) polymer content, a 0.03 emulsifier/water weight ratio, a 0.05emulsifier/monomer weight ratio and a 17 nm average particle diameter, which is very important for the industrialization of the microemulsion polymerization technique.     

丙烯酸甲酯与醋酸乙烯酯的种子乳液聚合

以过硫酸铵（ＡＰＳ） 为引发剂,合成了粒径分布较均匀的聚醋酸乙烯酯种子乳液（ＰＶＡｃ） ,然后以丙烯酸甲酯（ ＭＡ） 为第二单体和以油溶性偶氮二异丁腈（ＡＩＢＡ） 为引发剂,分别进行不溶胀与溶胀条件下的无皂种子乳液聚合,并用透射电子显微镜（ＴＥＭ） 表征了胶粒形态．表明在不溶胀条件下,胶粒形态随ＰＶＡｃ／ ＭＡ 重量比的不同而变化,当ＰＶＡｃ／ ＭＡ 为１／２ 时,形成以ＰＭＡ 为核,ＰＶＡｃ 为壳的胶粒．在溶胀条件下则得到类似互穿网络型乳胶粒．     

Influence of mass transfer at the monomer-water interface on polymerization emulsion

A quasi-spontaneous process of mass transfer takes place at the interface of a monomer and water in the presence of surface-active substances soluble in both phases as a result of their diffusion through the interfacial boundary. This process is accompanied by the formation of a microemulsion whose particle size depends on the emulsifier concentration and its molecular structure. While investigating various nonionic surface-active substances as emulsifiers in the emulsion polymerization of vinyl acetate, it was established that polymerization occurs in droplets of the monomer microemulsion in water, which are formed as a result of mass transfer at the interface.     

Temperature-induced phase separation in pseudoternary mixtures of Triton X-100–butanol–kerosene–water

The transparent Winsor IV domain in the phase diagram of the mixtures of emulsifier (Triton X-100 and butanol), oil (kerosene), and water is found to be 34% of the total phase diagram in presence of emulsifier with surfactant:cosurfactant::1:1, and is water dominant. Increase in cosurfactant/surfactant ratio inverts the Winsor IV domain to become oil rich. The plot of conductance of the microemulsions prepared by substituting water by brine against water content depicts the existence of three distinct phases like oil-in-water, bicontinuous, and water-in-oil microemulsion in the phase diagram. The phase contrast micrographs of the mixtures of different compositions in these three different phases reveal the existence of microdroplets of oil dispersed in water and water dispersed in oil. Further, the dynamic light scattering studies of these solutions reveal an inhomogeneity in the size distribution of the droplets. A temperature-induced clouding in the microemulsion domain leading to phase separation has been observed. Additives like glucose, sucrose, and sodium chloride decrease the cloud point (CP), while addition of ammonium thiocyanate increases it. A quantitative relationship of the clouding temperature with the composition of the microemulsion has been established. With increase in oil and emulsifier, the cloud point of the microemulsion increases. The separated phases after the clouding have been used for preconcentration of water-soluble metal ions as well as oil-soluble dyes. The turbid systems on heating led to separation into three isotropic phases which are found to be stable at ambient temperature. The stability of these phases is ascribed to the formation of stable microemulsions by mass transfer from one phase to other.     

聚苯乙烯-甲基丙烯酸甲酯功能微球的合成

本文研究了在用乳液聚合法合成苯乙烯/甲基丙烯酸甲酯共聚功能微球过程中,乳化剂、电解质、油水比、溶剂等因素对共聚胶乳微粒的粒径大小和粒度分布的影响。结果表明,乳化剂的种类和浓度对生成胶乳微粒的粒径有很大影响,且胶乳微粒的粒径随电解质浓度的增加以及油水比的减小而减小,加入溶剂可明显提高所得微粒的粒径。     

油酸单乙醇酰胺聚氧乙烯醚微乳液体系的研究

以油酸单乙醇酰胺聚氧乙烯醚作为乳化剂制备水包油型微乳液.通过拟三元相图、粒径大小及粒径分布确定较优配方:复配表面活性剂(由油酸单乙醇酰胺聚氧乙烯醚和吐温20组成)的亲水亲油平衡值(HLB值)为15,助表面活性剂为正丁醇,复配表面活性剂与助表面活性剂的质量比(Km值)为1,混合表面活性剂与正辛烷的质量比(S/O值)=1∶...     

Study the effect of HLB of surfactant on particle size distribution of hematite nanoparticles prepared via the reverse microemulsion

Hematite nanoparticles have been synthesized via reverse microemulsion route at room temperature. The microemulsion system, contained water, chloroform, 1-butanol, and surfactant, was combined with iron nitrate solution to result iron oxide nanoparticles precipitation. Three technical surfactants, with different structures and HLB (hydrophile–lipophile balance) values were employed and the effects of the HLB values on the hematite particle size were investigated. The prepared particles were evaluated by BET, XRD and TEM techniques. These results showed that the iron oxide particle size and particle size distribution increased with increasing surfactant HLB values.     

Oil Base Mud. Part I: Synthesis of Some Local Surfactants Used as Primary Emulsifiers for Oil Base Mud and Evaluation of Their Rheology Properties

Six oil soluble nonionic surfactants with different HLBs have been prepared. Their HLBs situate between 3.9 and 6.7. Transesterification was carried out for glycerol and triethanol amine with oleic acid at different moles to obtain six emusilifiers. They named glycerol momooleate (I), glycerol diooleate (II), glycerol trioleate (III), triethanol amine mono-, di- and tri-oleate (IV), (V,) and (VI). The chemical structure was confirmed using; the elemental analysis, FTIR and ¹HNMR. They were evaluated as a primary emulsifiers (PE) for thdrilling fluids (oil base mud) comparing with a currently used primary emulsifier (Fc). The water in oil base mud (w/o emulsions) was prepared. The concentration of emulsifiers and their HLB exhibited interesting rheology properties including shear-thinning behavior, yield value, viscoelastic effects, thixtropy, gel strength, and filtration loss. The rheology properties of such emulsions strongly depended on the average size distribution of the dispersed droplets that could be varied both with the bulk concentration and HLB value of the emulsifiers. The interfacial and surface properties of these emulsifiers suggest that the droplet size of the dispersed phase and bulk concentration are strongly related to the HLB value of emulsifiers. The w/o emulsion (mud formulation) stability is sensitive to the droplet size of the dispersed phase and HLB value of the used emulsifier. The results were discussed on the light the chemical structure of the primary emulsifiers and the emulsion ingredients.     

Model filled polymers. XI. Synthesis of monodisperse crosslinked polymethacrylonitrile beads

Monodisperse polymethacrylonitrile beads of varied size and crosslink density are prepared by emulsion copolymerization of methacrylonitrile and allylmethacrylate in the absence of emulsifier. The particle size is very sensitive to polymerization temperature and initiator concentration. Because of a nitrile group effect, the maximum conversion varies with reaction conditions. The highest conversion obtained was 82%. © 1992 John Wiley & Sons, Inc.