Styrene miniemulsion polymerization stabilized by carboxylated polyurethane. I. Stability and polymerization

Stability of the styrene miniemulsion costabilized by carboxylated polyurethane resins was investigated. The shelf life and the droplet size were measured. The results show that styrene miniemulsion costabilized by carboxylated polyurethane can be prepared although it is not as efficient as is hexadecane. The shelf life of the miniemulsion is influenced by the amount of the polyurethane and sodium dodecyl sulfate. The alkaline condition and the smaller molecular weight of the polyurethane are in favor of the stability of the miniemulsion. The polymerization results show that the hydrophility of the particle or droplet surface plays an important role in the process of the nucleation and polymerization. Homogeneous nucleation and droplet nucleation coexist in these systems. Nucleation lasts to 40–60% conversion of the monomer in the acid medium, but it continues until the end of the polymerization in the alkaline medium. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1933–1940, 2003     

Synthesis of nanocolorants with crosslinked shell by miniemulsion polymerization stabilized by waterborne polyurethane

Nanocolorants were prepared by miniemulsion polymerization, in which waterborne polyurethane was used as surfactant for the first time. Transmission electron microscopy (TEM), atomic force microscopy (AFM), and dynamic light scattering (DLS) were utilized to confirm the particle diameters and particle size distributions (PSD). The results indicated that nanocolorants with relatively small particle size diameters and narrow particle size distributions could be easily prepared by this method. Simultaneously, the particle size could be controlled by adjusting the concentration of waterborne polyurethane surfactant (WPU), and the obtained nanocolorants exhibited high stability against electrolyte, lightness, and strong color depth owing to the nanoscale effects of the nanocolorant particles. Furthermore, the prepared nanocolorants achieved superior migration fastness and good thermal stability.     

Hybrid acrylic–polyurethane latexes: Emulsion versus miniemulsion polymerization

Two kinds of hybrid acrylic–polyurethane (PUA) latexes are compared according to their synthesis and properties. The acrylic part is a copolymer of styrene, methyl methacrylate, and butyl acrylate. The PUAs are based on the polycondensation of isophorone diisocyanate and poly(propylene glycol) using butanediol and ethylene diamine as chain extenders. The first class result from the polymerization of miniemulsions of solutions of PU in the mixture of monomers using benzoyl peroxide as an initiator at 80°C. In the second class PUs modified by neutralized dimethylolpropionic acid are used as seeds and emulsifiers for emulsion polymerization of the monomer mixtures initiated with azobisisobutyronitrile at 75°C. The polymerization kinetics are compared, as well as the morphology of the latex particles. Films are obtained upon coalescence of these latexes, and the surface composition of these films and their tensile properties are studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3927–3941, 2006     

Waterborne oil‐modified polyurethane coatings via hybrid miniemulsion polymerization

As part of a wider effort to develop a new class of waterborne coatings, hybrid miniemulsion polymerization was carried out with acrylic monomers (methyl methacrylate, butyl acrylate, and acrylic acid) in the presence of oil‐modified polyurethane resin. Latexes with different ratios of resin to acrylic monomers were synthesized. The monomer emulsions prepared for hybrid miniemulsion polymerization showed excellent shelf‐life stability (>5 months) and the polymerization was run free of coagulation. Solvent extraction indicated that the grafting efficiency of polyacrylics was greater than 29% for all the samples produced. A ¹³C solution NMR spectrum showed that a substantial fraction of the original carbon double bonds (>61%) in oil‐modified polyurethane remained after polymerization for film curing. Films obtained from the latexes presented good adhesion properties and fair hardness properties. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 105–114, 2000     

微小乳液聚合制备丙烯酸酯杂化聚氨酯分散液

微小乳液聚合工艺技术在25~30年前即已问世,但用于丙烯酸酯杂化聚氨酯分散液的制备仅有10年历史。用该工艺技术可有效制得稳定的纳米级丙烯酸酯杂化聚氨酯分散液,其性能独特。本文阐述了微小乳液聚合工艺的原理、影响因素、存在问题和解决措施,并以实例说明之。     

Kinetics and colloidal parameters of miniemulsion polymerization of butyl acrylate

BACKGROUND: The miniemulsion polymerization of butyl acrylate initiated by a macromonomeric azoinitiator (macroinimer, MIM) and stabilized by the non‐ionic emulsifier Tween 60 (TW‐60) was investigated. RESULTS: The monomer conversion and the polymerization rate increase with the amount of MIM and then decrease. The desorption rate constants were estimated using the Ugelstad/O'Toole, Gilbert and Nomura models. The Ugelstad/O'Toole and Gilbert models suggest an increase in the k′_des value with increasing emulsifier concentration at the highest MIM concentration while the Nomura model proposes no variation in k′_des with an increase in both TW‐60 and MIM concentrations. The polymerization rate increases in the following order with regard to initiator: MIM < ammonium persulfate < dibenzoyl peroxide < 2, 2′‐azobisisobutyronitrile. CONCLUSION: The increase in the rate of polymerization can be discussed in terms of both increased particle concentration and the gel effect. The size of the polymer particles decreases and the number of polymer particles increases with both TW‐60 and MIM concentrations. This behaviour is attributed to the formation of a larger number of smaller monomer and/or polymer particles and higher particle nucleation rate. The observed long nucleation period for the MIM‐initiated polymerization is attributed to the creation of a crosslinked structure and the immobilization of MIM chains. Copyright © 2009 Society of Chemical Industry     

Thermal storage nanocapsules by miniemulsion polymerization

Paraffin wax was nanoencapsulated by miniemulsion polymerization. Low solid content batch polymerizations were carried out and the influence of paraffin wax/methyl methacrylate ratio on polymeriztion kinetics, phase change properties, and thermal stability were investigated. Paraffin concentration controls the nucleation mechanism and nanocapsules particle size. The latent heat capacity increases as the content of encapsulated paraffin wax increases. The maximum amount of encapsulated paraffin wax achieved under the experimental conditions was 60 wt %, presenting a latent heat capacity of 140.3 J/g. Moreover, the encapsulated systems present in all cases better thermal stability than pure paraffin wax. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

细乳液聚合制备含氟丙烯酸酯聚氨酯共聚物

采用细乳液聚合法,制备了稳定的含氟丙烯酸酯聚氨酯细乳液。用FT-IR表征了丙烯酸酯聚氨酯预聚体及其共聚物的结构组成;考查了细乳液的稳定性;用透射电子显微镜(TEM)观察了乳胶粒的形态;用接触角法表征了乳胶膜对水和正十六烷的接触角。     

Kinetics and effect of surfactant and cosurfactant on miniemulsion polymerization of acrylate monomers

The effects of the type and amount of the surfactant and cosurfactant on the miniemulsion polymerization of acrylate monomers were studied, and the comparison of the kinetics between miniemulsion polymerization and conventional emulsion polymerization was discussed in the presence of reactive surfactant allyloxy nonylphenol propyl polyoxyethylene (10), ether sulfate (DNS-86), and reactive cosurfactant stearyl methacrylate (SMA). The results showed that the obtained polyacrylate miniemulsion had a high monomer conversion rate and a low coagulum fraction, which were affected little by the surfactant and cosurfactant type. When the surfactant and cosurfactant amounts were all 2 wt%, the contact angle of the prepared polyacrylate miniemulsion with DNS-86/SMA and the water absorption fraction of the latex film were 39° and 8.3 wt%, respectively. FTIR results confirmed that DNS-86 and SMA took part in the polymerization of acrylate monomers. In the miniemulsion polymerization of acrylate monomers with DNS-86/SMA, monomer droplet nucleation was the main nucleation style.     

细乳液聚合法制备疏水性纳米二氧化硅-丙烯酸酯杂化乳液

采用细乳液聚合法制备了疏水性纳米二氧化硅-丙烯酸酯杂化乳液,研究了杂化乳液薄膜的应力-应变性能,并通过透射电子显微镜、X射线光电子能谱、扫描电子显微镜及凝胶渗透色谱对杂化乳液进行了表征.结果表明:杂化乳液薄膜的拉伸强度、扯断伸长率明显优于纯丙烯酸酯乳液薄膜;在杂化乳液中,二氧化硅被丙烯酸酯包裹,两相的相容性很好;杂化乳液的相对分子质量及其分布基本不随着疏水性二氧化硅用量的增加而变化,与纯丙烯酸酯乳液相当.     

Incorporation of high oil content in polyvinyl acetate nanoparticles produced by batch miniemulsion polymerization stabilized with a polymeric stabilizer

Nanoparticles (NPs) have been widely applied in the biomedical area. In order to satisfy the requirements for biomedical applications, sodium lauril sulfate (SLS) and hexadecane, widely used as anionic surfactant and co‐stabilizer, were successfully replaced by biocompatible compounds, in order to obtain poly(vinyl acetate) (PVAc) NPs via miniemulsion polymerization. The incorporation of high oil content in PVAc NPs was investigated, using different poly(vinyl alcohol) (PVOH) concentrations as polymeric surfactant. Besides the polymeric surfactant, lecithin and Miglyol 812, a triacylglycerol of saturated fatty acids obtained from coconut oil, were used as surfactant and co‐stabilizer, respectively. A high Miglyol 812 content was incorporated in the PVAc NPs and the morphology was investigated by TEM. The influence of PVOH concentration on the droplet nucleation mechanism and final morphology of PVAc NPs was evaluated. High PVOH concentration favored micellar particle nucleation. According to the TEM images, hemispheres nanoparticles were obtained. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41365.     

Encapsulation of magnetic particles via miniemulsion polymerization of styrene. II. Effect of some parameters on the polymerization of styrene

Effects of some parameters on the polymerization of Styrene (St) during encapsulation of iron oxide particles via miniemulsion polymerization have been investigated. At the early stage of reaction, polymerization rate increased slightly with the increase of sonicating time, and then it leveled off. The polymerization rate increased with the increase of KPS at the early stage of polymerization, which tendency is analogous to the result of polymerization of St in miniemulsion without the presence of iron oxide particles. The increase of iron oxide not only decreased the polymerization rate but also resulted in poorer monodisperse of the particles when keeping the amount of dispersant constant. The dispersant played an important role in the encapsulation of magnetic particles via miniemulsion polymerization of St. It not only made the iron oxide disperse well in monomer droplets but also led to a much faster polymerization than that of no dispersant in system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

通过细乳液聚合方法制备自交联型有机硅乳液

苯乙烯与甲基丙烯酸-3-三甲氧基硅丙酯(M PS)经细乳液聚合,制得了稳定的自交联型的水分散涂料,用透射电子显微镜(TEM)、动态光散射仪(DLS)和红外光谱(IR)表征了乳胶粒的形态和结构。发现与传统乳液聚合相比,细乳液聚合法可显著提高乳液的稳定性,且M PS加入量的增加会导致乳液稳定性降低。     

细乳液聚合制备聚丙烯酸酯共聚细乳液的研究

以正十六烷为助稳定剂,十二烷基硫酸钠为乳化剂,采用细乳液聚合法合成了聚丙烯酸酯共聚乳液.研究结果表明,当乳化剂质量分数为3%,助稳定剂质量分数为2%时,乳液粒子平均粒径为89.5 nm,乳液稳定性好.成膜后综合性能优异.此外,在聚合体系中引入2%的交联剂N-羟甲基丙烯酰胺,胶膜的耐水性和拉伸强度有显著的提高.     

Vinyl polymerization by metal complexes. XVIII. Kinetics of the polymerization of acrylonitrile initiated by imidazole-copper-(II) complexes

A study on the kinetics and mechanism of the polymerization of acrylonitrile initiated by imidazole and 2-substituted imidazole-copper-(II) complexes was made in dimethyl sulfoxide solution at 40–70°C. The rate of polymerization, Rp, could be expressed as follows: The overall activation energies of these polymerization processes are in a range from 14.2 to 69.1 KJ mole^-1. From the data of electronic spectra and electron paramagnetic resonance, it was confirmed that the polymerization in question could be initiated by free radicals which were formed by the reduction of copper-(II) complex to copper-(I) complex, and the latter formed a new complex with polyacrylonitrile resulted.     

以含氟预聚物为助稳定剂的苯乙烯细乳液聚合

以苯乙烯(St)和甲基丙烯酸十二氟庚酯(G04)的无规共聚物(PSF)作为助稳定剂,进行St的细乳液聚合,考察了不同含氟量的PSF对转化率、聚合速率R_p、液滴粒径和成核粒子数的影响。结果表明,当含氟量由0增加到34.9%,转化率由67.5%增加到80.1%,R_p由0.75×10^-2 mol · L^-1·min^-1提高到1.74×10^-2 mol ·L^-1·min^-1;PSF的含氟量对细乳化后液滴粒径的影响较小,但对聚合过程中成核粒子数有较大影响。当含氟量由0增加到34.9%时,反应3 h后,体系成核粒子数由每升1.83×10^16个增加到2.07×10¹⁶个,并初步分析了PSF可以单独作为助稳定剂的作用机理。     

含氟丙烯酸酯共聚物细乳液的制备及表征

采用细乳液聚合法,制备了稳定的含氟丙烯酸酯(FA)、甲基丙烯酸甲酯(MMA)和丙烯酸丁酯(BA)的三元共聚细乳液.用FT-IR表征了聚合物的结构组成;考查了细乳液的稳定性、乳胶膜的吸水性及耐溶剂性;用接触角法表征了乳胶膜的表面自由能.     

细乳液聚合纳米乳胶荧光颜料的制备

采用细乳液聚合法制备了纳米乳胶荧光颜料,研究了溶剂黄43用量,乳化剂、助乳化剂种类和用量,引发剂用量和超声波处理时间对纳米乳胶荧光颜料性能的影响。结果表明,纳米乳胶荧光颜料较佳的制备工艺为:溶剂黄43、十六烷(HD)和过硫酸铵(APS)的质量分数分别为1.5%、1.5%和0.8%(以单体质量计),乳化剂1-烯丙氧基-3-(4-壬基苯酚)-2-丙醇聚氧乙烯(10)醚硫酸铵(DNS-86)用量为0.019 11 mol/L,超声波处理时间9 min,在该条件下制备的纳米乳胶荧光颜料的粒径为162.1 nm,具有较高的耐热和离心稳定性,纳米乳胶荧光颜料的最大荧光发射波长517 nm,最大吸收波长425 nm。     

聚合法水性聚氨酯的生产工艺

水性聚氨酯是一种环境友好型材料。比较了水性聚氨酯的多种合成方法,从预缩聚系统、乳化分散系统、脱溶前缓冲系统、脱溶系统、产品包装系统、真空及溶剂回收系统等方面介绍了大产能聚合法间歇工艺生产水性聚氨酯的工艺流程,总结了该工艺特点。