Emulsifier‐minor emulsion copolymerization of BA‐MMA‐St‐MAA (or AA)‐N‐MA

A novel emulsion polymerization technique referred to as emulsifier‐minor emulsion polymerization was achieved by the copolymerization of methyl methacrylate, butyl acrylate, and styrene (MMA‐BA‐St) with a combination of water‐soluble ionic monomers [methacrylic acid (MAA) or acrylic acid (AA)] and nonionic monomers (N‐methylol acrylamide). In the technique, water‐soluble monomers play a crucial role in the stabilization of the latex particles as they can be bound to the particle surface and form a hydrate protective layer, which exhibits steric and/or electrostatic effects to prevent particle coagulation. The minor but over its critical micelle concentration emulsifier sodium alkylated diphenyl ether disulfonate (DSB) results in the nucleation of particles mainly by the micelle nucleation mechanism and thus determines the polymerization rate, the particle size, and the number. The film water resistance of the latices can be improved, and the foaming capacity of can be lowered by using technique instead of conventional emulsion polymerization. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2923–2929, 2004     

Polymer–metal composite particles: Metal particles on poly(St‐co‐MAA) microspheres

Poly(styrene‐co‐methacrylic acid) P(St‐co‐MAA) microspheres with a monodisperse size distribution were prepared by emulsifier‐free emulsion copolymerization of St and MAA. The effects of MAA content on the polymerization rate and the content of MAA in the copolymer were investigated by gravimetrical and IR methods, respectively. The results of XPS measurement indicated the presence of a carboxyl functional group. By chemical metal deposition, nickel or palladium particles were formed and deposited on the surface of P(St‐co‐MAA) microspheres to form P(St‐co‐MAA)Ni or P(St‐co‐MAA)Pd composite particles. XRD measurement and TEM observation confirmed that nickel and palladium metal particles in a small size (20–40 nm) were distributed on surface of the copolymer microspheres. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1693–1698, 2000     

含3nm硅溶胶的苯丙杂化乳液的制备与性能研究

在单一乳化剂存在下 ,用原位分散聚合方法制备了含 3 nm硅溶胶的苯丙杂化乳液。通过 FTIR、粒径分析、ζ电位和流变性能测试 ,表征了杂化乳液中的杂化效应、微粒形态及乳液稳定性 ,并与分别由 3 nm和 1 0 nm硅溶胶与苯丙乳液直接共混形成的杂化乳液进行了比较。与直接共混的杂化乳液成膜后的力学性能相比 ,由原位分散聚合形成的 3 nm硅溶胶杂化乳液成膜后 ,显示出较高的拉伸强度、拉伸模量和断裂伸长率。     

Statistical experimental strategies approach to emulsion copolymerization of styrene and n-butyl acrylate

A batch emulsion copolymerization for the preparation of styrene-n-butylacrylate (St/BA) copolymer latexes is investigated. A series of n-butylacrylate-styrene copolymer latexes were obtained by emulsion copolymerization in the presence of K₂S₂O₈ (KPS) as initiator and with/without emulsifier (sodium lauryl sulfate). The effect of such preparation conditions as initiator concentration, the St/BA ratio, reaction temperature, agitation rate, and emulsifier concentration on the polymerization rate, particle size of copolymer latex, and molecular weight distribution of the resulting copolymer (∼ 80% conversion), respectively, is systematically studied using fractional factorial design methodology. Fractional factorial analysis indicates that the effects of the St/BA ratio, reaction temperature, emulsifier concentration, as well as the two-factor interaction of temperature and emulsifier concentration, are the key variables influencing the polymerization rate. At ∼ 80% monomer conversion, statistical analysis clearly isolates emulsifier concentration as the dominant factor affecting average particle size of copolymer latex; results also indicate that the effects of the St/BA ratio, reaction temperature, and emulsifier concentration are major effects influencing the polydispersity of polymer molecular-weight distribution. For 7.30 g KPS/100 g monomer and 500 rpm agitation rate, the conditions for minimizing molecular-weight distribution (∼ 80% conversion) occur for a reaction temperature, St/BA ratio, and surfactant concentration of 70°C, ∼ 3.59/1, and ∼ 2.08 g/100 g monomer, respectively, generating a minimum molecular-weight polydispersity of ∼ 3.0. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 551–563, 1998     

核/壳型聚硅氧烷丙烯酸酯复合乳液的制备

采用种子乳液聚合的方法制备了具有核/壳结构的聚硅氧烷丙烯酸酯复合乳液,研究了乳化剂、单体的投料方式及配比对乳液性质的影响。结果表明:通过种子乳液聚合,得到了含氢聚硅氧烷/丙烯酸丁酯/苯乙烯/甲基丙烯酸甲酯/甲基丙烯酸（PHMS/BA/St/MMA/MAA）共聚物复合乳液,乳液性能稳定,该乳液所制得的胶膜具有优良的性能。     

Preparation of carboxylated polymer emulsion particles in which carboxyl groups are predominantly localized at surface layer by using the seeded emulsion polymerization technique

It was studied how to localize carboxyl groups at the particle surface in a preparation of styrene (S)/butyl acrylate (BA)/methacrylic acid (MAA) polymer emulsion. The relative distribution of carboxyl groups in the emulsion was determined by conductometric titration method: in serum, at surface, and inside particle. By seeded (two-stage) emulsion polymerization that S–BA–MAA terpolymer emulsion was first prepared at low pH and then second stage polymerization of S–BA was continued at high pH, S/BA/MAA polymer emulsion particles in which carboxyl groups are localized predominantly at the surface could be prepared.     

有机硅氧烷改性醋酸乙烯酯-丙烯酸酯乳液的合成与性能

采用种子乳液聚合,引入乙烯基三甲氧基硅烷(A-171),以十二烷基苯磺酸钠(DSB)和壬基酚聚氧乙烯(20)醚(OP-10)作复合乳化剂,以过硫酸钾(KPS)为引发剂,在反应温度为78±2℃条件下,合成了A-171改性醋酸乙烯酯(VAc)-丙烯酸酯共聚乳液。实验采用单体滴加工艺,考察了配方中丙烯酸丁酯(BA)、甲基丙烯酸(MAA)和A-171用量对共聚物性能和乳液聚合过程的影响,并用红外光谱仪(FTIR)、粒度仪和差示量热扫描仪(DSC)对共聚物的结构及性能进行了表征。结果表明,引入w(BA)=10%~15%(相对于配方中单体总质量,下同)、w(MAA)=4%、w(A-171)=1%到VAc-丙烯酸酯共聚物乳液中,共聚物乳液涂膜的吸水率<5.0%,耐寒性通过10个循环,60℃加速贮存稳定性>100 d。     

Preparation of micron‐size monodispersed PS/P(St/MAA) microspheres by seeded dispersion polymerization

Uniform polystyrene (PSt) particles with the size of 1.9 μm were first prepared via dispersion polymerization, and then used as the seeds in a second‐stage dispersion copolymerization of styrene (St) and methacrylic acid (MAA) to produce carboxyl‐carrying microspheres. The PSt seed particles were swollen by monomer mixture of St and MAA, including an oil‐soluble initiator 2,2′‐azobisiso‐butyronitrile (AIBN), before polymerization. Finally, uniform PS/P(St/MAA) (polydispersity index, PDI = 1.02) microspheres with the size of 2.2 μm were obtained. The average particle size and size distribution of the final microspheres were investigated. MAA contents between 54 and 97 mg/g were detected from the PS/P(St/MAA) particles produced under different conditions. Dispersion medium has great influence on the kinetics of polymerization, due to its effect on the partitioning of monomers, solvents, and initiator in the particle phase, probably as well as on the conformation of the dispersion agent on the surface of the particles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3586–3591, 2006     

中空聚合物微球的制备——种子及核乳胶粒的制备

为了制得具有中空结构的聚合物微球,首先以十二烷基苯磺酸钠(SDBS)为乳化剂,在其用量低于CMC的条件下,进行甲基丙烯酸甲酯(MMA)、甲基丙烯酸(MAA)和丙烯酸丁酯(BA)的乳液聚合,制备了带羧基的种子乳胶粒.然后采用MMA、MAA和二乙烯基苯为单体进行种子乳液聚合,制备了轻度交联的带羧基的核乳胶粒.该核乳胶粒经过核-壳乳液聚合和适当的碱处理工艺就可成为具有中空结构的聚合物微球.采用粒度仪测定了乳胶粒的直径及其分布,采用TEM对乳胶粒结构形态进行了表征.研究了种子及核乳胶粒制备过程中单体加料方式、乳化剂用量及羧基单体种类等因素对聚合稳定性、乳胶粒直径及其分布以及最终的中空聚合物微球结构形态的影响,确定了制备种子及核乳胶粒的最佳工艺条件.在制备种子阶段,SDBS用量为单体总量的0.5%,采用一次性加入单体的进料工艺;在核乳胶粒制备阶段,以MAA为羧基单体,所有单体采用"饥饿式"加料,半连续补加乳化剂并使乳化剂用量为核单体总量的0.15%时可保持聚合稳定性并保证无新乳胶粒生成.     

Using anionic polymerizable surfactants in ultrasonically irradiated emulsion polymerization to prepare polymer nanoparticles

An ionic polymerizable surfactant, sodium sulfopropyl‐laurylmaleate (M12), was synthesized and used as an emulsifier, an initiator, and a comonomer in ultrasonically irradiated emulsion polymerization. FTIR spectra and gravimetric method results indicated that copolymers P(Styrene‐M12) and P(Butylacrlate‐M12) were prepared successfully by ultrasonically irradiated emulsion polymerization and the composition of M12 elevated with the increasing concentration of M12 added. TEM photographs of P(St‐M12) showed that the nanoparticles with small diameters (20–45 nm) were prepared. With the increase of M12 concentration, the particle size became smaller and the size distribution became wider. The P(BA‐M12) particles size was also small (<100 nm) but the size distribution was wide due to the high reactivity of BA. Because surfmer M12 was chemically bonded with the latex particles, the stability of the copolymer latex prepared by ultrasonically irradiated emulsion polymerization was much better than that of the homopolymer latex (PSt or PBA) prepared by the same way. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Polymer microgels prepared by emulsifier‐free emulsion polymerization of unsaturated polyesters and styrene

In the present work polymer microgels were prepared by emulsifier‐free emulsion copolymerization of unsaturated polyesters (UPs) with end carboxyl groups and styrene (St). The nucleation mechanism of UP‐St emulsifier‐free emulsion polymerization was proposed. The effects of the ratio of the monomers to water, pH, and the ratio of UP to St on the stability of polymerization and the yield of microgels were studied. It was found that the polymer microgels can be used to markedly improve the impact strength of UP. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3049–3053, 2000     

Preparation of hemispherical poly(4‐vinylpyridine‐co‐butyl acrylate)/poly(styrene‐co‐butyl acrylate) composite microspheres by seeded preswelling emulsion polymerization

Seeded preswelling emulsion polymerization was carried out by using monodispersed poly(4‐vinylpyridine‐co‐butyl acrylate) [P(4VP‐BA)] particles as the seed, and styrene and butyl acrylate as the second‐stage monomers under different polymerization conditions, to obtain hemispherical polystyrene (PST)‐rich–P4VP‐rich microspheres. Prior to polymerization, toluene was added into the preswelling system together with the second‐stage monomers. It was found that, with the increase of the amount of toluene, the particle morphology showed a tendency toward desirable hemispherical structure, and the colloidal stability of composite latex was improved. When the weight ratio of toluene/seed latex was increased up to 7.5/40 (g/g), the stable hemispherical latex could be obtained. However, when toluene was not added, the coagulum formed on the wall of the reactor during polymerization, and the composite particles with multiple surface domains (such as sandwich‐like, popcorn‐like) were formed. In addition, the final morphology of composite particles was influenced by the polarity of the seed crosslinker and the hydrophilicity of the second‐stage initiator, which could affect the mobility of poly(styrene‐co‐butyl acrylate) [P(ST‐BA)] chains. The morphology development during the polymerization was investigated in detail, and a schematic model was derived to depict the formation mechanism of hemispherical P(4VP‐BA)/P(ST‐BA) composite microspheres. The results revealed that the mobility of the P(ST‐BA) chains influenced the diffusion of the P(ST‐BA) domains on the surface of the P(4VP‐BA) matrix. When the mobility of the P(ST‐BA) chains allowed small‐size P(ST‐BA) domains to coalesce into one larger domain, complete phase‐separated morphology (hemisphere) could be achieved. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3811–3821, 2003     

Synthesis of well‐defined,functionalized polymer latex particles through semicontinuous emulsion polymerization processes

The design of a semicontinuous emulsion polymerization process, primarily based on theoretical calculations, has been carried out with the objective of achieving overall independent control over the latex particle size, the monodispersity in the particle size distribution, the homogeneous copolymer composition, the concentration of functional groups (e.g., carboxyl groups), and the glass‐transition temperature with n‐butyl methacrylate/n‐butyl acrylate/methacrylic acid as a model system. The surfactant coverage on the latex particles is very important for maintaining a constant particle number throughout the feed process, and this results in the formation of monodisperse latex particles. A model has been set up to calculate the surfactant coverage from the monomer feed rate, surfactant feed rate, desired solid content, and particle size. This model also leads to an equation correlating the polymerization rate to the instantaneous conversion of the monomer or comonomer mixture. This equation can be used to determine the maximum polymerization rate, only below or at which monomer‐starved conditions can be achieved. The maximum polymerization rate provides guidance for selecting the monomer feed rate in the semicontinuous emulsion polymerization process. The glass‐transition temperature of the resulting carboxylated poly(n‐butyl methacrylate‐co‐n‐butyl acrylate) copolymer can be adjusted through variations in the compositions of the copolymers with the linear Pochan equation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 30–41, 2003     

单分散聚苯乙烯微球的制备

以苯乙烯单体为原料,过硫酸钾为引发剂,采用了无皂乳液聚合法制备单分散性较好的聚苯乙烯微球。为了使制备方法更加完善,主要研究了离子强度,引发剂浓度,聚合单体的浓度,乳化剂添加量等各因素对得到的聚苯乙烯微球粒径、分散度的影响,同时对得到的聚苯乙烯微球用扫描电镜(SEM),激光粒度仪进行表征,结果表明合成的聚苯乙烯微球表面光滑,单分散性好,球形度好,平均粒径约100nm。     

水性上光油用苯丙共聚乳液的合成及性能表征

以苯乙烯(St)、丙烯酸丁酯(BA)和马来酸酐(MAH)为共聚单体,过硫酸钾(KPS)为引发剂,十二烷基硫酸钠(SDS)/壬基酚聚氧乙烯醚(OP-10)为复合乳化剂,采用半连续加料的乳液聚合法合成出一种水性上光油用苯丙共聚乳液。考察了玻璃化转变温度(Tg)、引发剂和乳化剂含量等对该乳液单体转化率、平均粒径、黏度和表干时间等影响,并对该乳液的热稳定性能进行了研究。结果表明:当w(引发剂)=0.6%、w(复合乳化剂)=1.2%和m(MAH)∶m(BA)∶m(St)=4.6∶36.3∶50.5时,该乳液具有良好的综合性能,完全满足水性上光油的使用要求,并且可在高温环境中使用。     

Monodispersed composite particles prepared via emulsifier‐free emulsion polymerization using waterborne polyurethane as microreactors

Monodispersed polystyrene particles in submicrometer size were intriguingly prepared through emulsifier‐free batch‐seeded emulsion polymerization using nonmonodispersed waterborne polyurethane (WBPU) beads as microreactors. Different feed ratios of styrene (St)/WBPU for the preparation of composite particles were investigated, and the size–growth course was experimentally followed. The morphology and dispersity of the particles were characterized by scanning electron microscopy together with dynamic laser scattering particle size analyzer. Their inside structure was further characterized by transmission electron microscopy with ultramicrotomy combined with X‐ray photoelectron spectroscopy for the composite particles' surface analysis. The probable grafting polymerization of St from WBPU was verified by Fourier transform infrared spectroscopy and nuclear magnetic resonance instrument. The obtained composite particles were again employed as the seeds in the emulsion copolymerization of methyl methacrylate. As a result, the formed multilayered composite particles with reverse core–shell structure were also monodispersed and spherical. The mechanism of the formation of the monodispersed particles was proposed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40985.     

核壳结构苯丙乳液上光油的研制

采用预乳化工艺及半连续种子聚合法,通过St-BA-MMA-AA四元共聚反应,制得了具有核壳结构的苯丙乳液。讨论了乳胶粒子大小及形态对MFT的影响,并研究了乳化剂用量、阴／非离子乳化剂配比、核壳两阶段乳化剂配比及功能性单体的用量及加入方式对乳液性能的影响。     

有机硅改性丙烯酸酯乳液的性能研究

采用-γ甲基丙烯酰氧基丙基三甲基硅烷(KH570)改性丙烯酸酯类聚合物,合成了丙烯酸酯乳液,研究了单体配比、乳化剂用量、聚合方法对乳液性能的影响。结果表明单体配比为MMA﹕BA﹕MAA=54﹕44﹕2、乳化剂用量为3%时乳液的综合性能较好。     

阳离子型PAE/St/BA共聚物乳液的结构与性能

以过硫酸铵(APS)为引发剂,吐温80(Tween-80)和OP-10为乳化剂,自制的不饱和聚酰胺多胺环氧氯丙烷树脂(PAE)、苯乙烯(St)和丙烯酸丁酯(BA)为原料,采用乳液聚合的方法制备PAE/St/BA共聚物乳液。通过傅里叶变换红外光谱(FTIR)、热重分析(TGA)、Zeta电位及粒径分析、静态接触角和扫描电镜(SEM)对乳液的结构和性能进行了表征,并研究了不饱和PAE树脂用量对乳液施胶性能的影响。结果表明,当聚合反应中不饱和PAE树脂用量为3%(以乳液质量计),乳液用量为0.6%(以施胶液质量计)时,PAE/St/BA共聚物乳液施胶效果较好。     

Preparation and structure control of hollow polymer particles: Influence of seeded emulsion polymerization and alkalization treatment process

Hollow polymer latex particles containing a hydrophilic core were prepared by seeded emulsion polymerization with MAA/BA/MMA/St as comonomers, followed by stepwise alkalization treatment with ammonia. The size and morphology of composite latex particles was determined by TEM. The effects of the seeded emulsion polymerization conditions and alkalization treatment on the size and hollow structure of latex were investigated. The results showed that the optimum content of crosslinking agent in the shell polymers was about 0.5–1.0 wt %, emulsifier was about 0.8–1.1 wt %, and the core/shell weight ratio was 1/7. To obtain uniform hollow latex particles with large size, the starved feeding technique should be adopted in seeded emulsion polymerization, and the neutralization temperature should equal to the T_g of the shell polymer. Then, the obtained polymer particles under this condition had an excellent hollow structure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009