Styrene emulsion polymerization in the presence of a maleate-functional surfactant

Dodecylhemiester of maleic anhydride is a very good anionic stabilizer for the emulsion polymerization of styrene. Rather high solid contents may be produced. Up to about 70% of the surfactant can be grafted onto the surface of the particles. Upon floculation with calcium salt, only 3% of the surfactant is left in the washing water. © 1997 John Wiley & Sons, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

J Appl Polym Sci 65: 2289–2296, 1997     

Morphology control of conducting polypyrrole nanostructures via operational conditions in the emulsion polymerization

Polypyrrole (PPy) nanostructures with diameter smaller than 100 nm were synthesized by chemical oxidative polymerization of pyrrole in the presence of cetyl trimethylammonium bromide and sodium dodecyl sulfate as surfactants. Hydrochloric acid was used as dopant, and a solution of potassium peroxydisulfate was used as initiator. The influence of polymerization temperature, feeding strategy, and the type of surfactant on the morphology and conductivity of PPy nanostructures were investigated and well‐described. A simple route just via controlling the operational conditions in the emulsion polymerization is reported to obtain nanostructured PPy with desirable morphology and relatively good conductivity. The analysis results demonstrated that the conductivity of samples is highly affected by their morphology whereas PPy nanofibers exhibited higher conductivity respecting the other morphologies (0.66 S/cm). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44697.     

Synthesis of polystyrene-clay nanocomposites via emulsion polymerization using a reactive surfactant

Summary Polystyrene-clay nanocomposites were synthesized via emulsion polymerization of styrene in the presence of montmorillonite particles and a reactive cationic surfactant as the emulsifier. The reactive surfactant, vinylbenzyldodecyldimethylammonium chloride (VDAC), was synthesized by the quaternization reaction of vinylbenzyl chloride with dimethyldodecylamine. Partially exfoliated nanocomposites were achieved as revealed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Polystyrene-clay nanocomposites prepared by emulsion polymerization have higher glass transition temperature and dynamic modulus than pure polystyrene. Received: 27 February 2001 /Revised version: 14 February 2002 /Accepted: 14 February 2002     

Ionic liquid as surfactant in microwave‐assisted emulsion polymerization

The aim of this work is to study the use of an ionic liquid (IL) as surfactant in emulsion polymerization reactions and to evaluate its effect when these reactions are heated under microwave irradiation. The IL 1‐n‐dodecyl‐3‐methylimidazolium chloride was chosen to replace the surfactant dodecyltrimethylammonium bromide (DTAB) in methyl methacrylate emulsion polymerizations. The conversion evolutions and the final average diameter of polymeric particles were quite similar for reactions using the surfactant DTAB or the IL, showing that the IL acted efficiently as surfactant in emulsion polymerizations. Comparing the polymerization reactions performed under microwave irradiation and conventional heating, reaction rate enhancements were obtained for both DTAB and IL. Using a pulsed scheme, under high‐power microwave irradiation, slightly higher reaction rates and molecular weights were obtained in reactions using IL, in comparison with surfactant DTAB, indicating the existence of some specific effects linked to IL–microwaves interaction. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Electroconductive performance of polypyrrole/graphene nanocomposites synthesized through in situ emulsion polymerization

The present study demonstrates a modified in situ emulsion polymerization (EP) approach convenient for the formation of polypyrrole/graphene (PPy/GN) nanocomposites with harnessed conductivities. A series of PPy/GN nanocomposites were prepared by loading different weight percent (wt %) of GN during in situ EP of pyrrole monomer. The polymerization was carried out in the presence of dodecyl benzene sulfonic acid, which acts as an emulsifier and protonating agent. The microstructures of the nanocomposites were studied by scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared, X‐ray photoelectron spectroscopy, UV–vis spectroscopy, Raman spectroscopy, photoluminescence spectroscopy and thermogravimetric analyses. The electrical conductivities of the nanocomposite pellets pressed at different applied pressures were determined using four probe analyzer. The electrical conductivities of the nanocomposites were considerably enhanced as compared to those of the individual PPy samples pressed at the same pressures. An enhanced conductivity of 717.06 S m^?1 was observed in the sample with 5 wt % GN loading and applied pressure of 8 tons. The results of the present study signify that the addition of GN in the PPy polymer harnesses both electrical and thermal properties of the polymer. Thus, PPy/GN nanocomposites with superior properties for various semiconductor applications can be obtained through direct loading of GN during the polymerization process. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41800.     

Synthesis of polypyrrole nanoparticles in natural rubber–polystyrene blend via emulsion polymerization

Nanoparticles of polypyrrole (PPy) in 40/60 wt % natural rubber (NR)–polystyrene (PS) blends were synthesized by emulsion polymerization using ferric sulfate [Fe₂ (SO₄)₃], sodium dodecyl sulfate (SDS), and n‐amyl alcohol as the oxidant, surfactant, and cosurfactant, respectively. The NR/PS/PPy blends were characterized by Fourier transform infrared spectroscopy (FTIR), elemental analysis, thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FESEM). FESEM micrographs showed that NR/PS/PPy blends were homogeneous, and PPy nanoparticles were well distributed throughout the binary matrix of NR/PS. The size of PPy particles in the blends was in the range of 26–80 nm. The electrical conductivities of the pellets prepared from NR/PS/PPy blends increased as the composition of PPy nanoparticles was increased, which were in the range of 8.9 × 10^?8 – 2.89 × 10^?4 S/cm. Thermal stability of the blends increased as the content of PPy was increased, as shown by TGA thermograms. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

可聚合表面活性剂 CS-1参与下的苯乙烯浓乳液聚合

合成了一种新型可聚合表面活性剂CS-1并应用于苯乙烯浓乳液聚合。GPC谱图表明聚合过程中同时存在苯乙烯的均聚以及苯乙烯／CS-1的共聚;反应初期苯乙烯／可聚合表面活性剂CS-1的共聚速率快于苯乙烯的均聚速率;均聚苯乙烯的相对分子质量随聚合时间增长有所下降。另外,十二烷基硫酸钠和CS-1体系中转化率数据也表明CS-1参与了苯乙烯的浓乳液聚合。     

乳化剂浓度对苯乙烯乳液聚合成核机理的影响

以苯乙烯（St）为单体、十二烷基硫酸钠（SDS）为乳化剂、过硫酸钾（KPS）为引发剂,重点研究了该乳液聚合体系中乳化剂浓度（[S]）对胶束成核和沉淀成核的影响规律。结果表明,当SDS浓度高于CMC时（[S]≥ 8mmol/L）,体系的成核以胶束成核为主;当[S]=2mmol/L时,体系的成核以沉淀成核为主;当2mmol/L<[S]< 8mmol/L时,体系同时以沉淀成核和胶束成核两种方式成核,且胶束成核所占的比例随着SDS浓度的增加而增大。研究了聚合反应过程中SDS浓度对单位体积水中乳胶粒个数（Np）的影响规律：当[S]≥8mmol/L时,Np∝[S]0.9;当[S]<8mmol/L时,Np∝[S]0.8。     

Effects of agitation in emulsion polymerization of vinyl acetate,ethylene, and N-methylol acrylamide

The emulsion polymerization of vinyl acetate monomer (VAM), ethylene and N-methylol acrylamide (NMA) was carried out in a high pressure stirred reactor using an Rushton flat blade impeller at a rotational speed of 300 rpm under a semi-batch polymerization process, which was subsequently grown by the continuous addition of monomers (VAM, ethylene, and NMA). The particle diameters of the samples withdrawn during polymerization were determined by using capillary hydrodynamic fractionation (CHDF). Also, the number of particles was calculated from the data obtained by CHDF. Coagulum formation was studied. It was found that coagulum formation increased with increasing conversion and auto-accelerated from ca. 20% conversion. The definition of coagulum in this research was presented. The coagulum formation pattern on the impeller was shown. Also, the flow pattern in the reactor under the same geometrical configuration and operating conditions was simulated.     

乳液聚合中的反应型乳化剂研究进展

介绍了反应型乳化剂的最近研究进展,并简述了其结构、分类和特点。探讨了可聚合乳化剂应用效果的几个影响因素和最佳可聚合乳化剂行为。对设计和使用可聚合乳化剂具有一定的指导作用。     

Kinetics of emulsion polymerization of styrene using the reactive surfactant HITENOL BC20

The effect of the reactive surfactant HITENOL BC20 (polyoxyethylene alkylphenyl ether ammonium sulfate; 20 U of ethylene oxide (EO)) on the emulsion polymerization of styrene was studied via reaction calorimetry (Mettler RC1; 70°C). For polymerizations carried out above the cmc of BC20, the reaction kinetics and evolution of the number of particles (N_p) resembled those reported using the conventional surfactant sodium lauryl sulfate, indicating that nucleation proceeded by a combination of micellar and homogenous nucleation (Interval I and Stage 2). The reaction rate (R_p) not only increased with increasing initiator (K₂S₂O₈) and surfactant concentrations, as expected, but the increase in rate in Stage 2 was dependent on the initiator concentration and independent of the surfactant concentration. This is consistent with the proposed nucleation mechanisms. The molecular weight increased with increasing surfactant concentration and decreasing initiator concentration as would also be expected for a conventional surfactant. The dependencies of R_p and N_p on the BC20 and initiator concentrations, however, were lower than the classical Smith‐Ewart values (R_p ∝ [E]^0.47–0.52; R_p ∝ [I]^0.21–0.25) although R_p was found to be directly proportional to N_p. Chain transfer to the reactive surfactant is considered a likely source of divergence. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thin polypyrrole films prepared by chemical oxidative polymerization

Polypyrrole (PPY) films with a thickness of 3–4 μm were obtained by chemical oxidation of pyrrole (PY) at the interface of chloroform and water with an oxidant (NH₄)₂S₂O₈. The films were compact and could be removed with a solid plate. The quality and compositions of these films varied with the molar ratios of the monomer and oxidant of the reaction systems. Overoxidation of polypyrrole was observed and confirmed by the characterizations via infrared spectra and elemental analysis of the films. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2169–2172, 1998     

Influence of agitation during emulsion polymerization of acrylic–styrene latexes on end product properties

Emulsion polymerization is influenced by system turbulence due to its heterogeneous nature. System effective agitation is necessary to keep the particles in dispersed phase, to prevent flocculation, to improve mass and heat transfer, phenomena that influence the reaction mechanism and kinetics as well as the final product properties and the properties of the product based on achieved latex. This paper presents the influence of agitation on properties of the product using the obtained latex, especially on its viscosity and rheological behaviour. It also presents the influence of system initial rheology scaling up.     

Application of a non-ionic amphiphilic maleic diester as polymerizable surfactant in free-radical emulsion polymerization

Summary A non ionic amphiphilic maleic diester with a poly(ethylene oxide) hydrophilic chain was used as a copolymerizable surfactant in batch free-radical emulsion polymerizations of styrene and n-butylacrylate. A good stability during the polymerization process was observed together with a high incorporation of the surfactant. Received: 14 December 1998/Revised version: 10 February 1999/Accepted: 10 February 1999     

State estimation for continuous emulsion polymerization

Various aspects of the use of extended Kalman Filters for tracking the states of continuous emulsion polymerization reactors are investigated. The importance of introducing meaningful nonstationary stochastic states to account for unknown impurities, initiator efficiencies, modelling errors, etc. is illustrated. The robustness of these state estimators to unmodelled and unmeasured disturbances, to modelling errors, and to input errors is evaluated. A procedure for selecting an optimal set of on-line sensors is presented. The emulsion polymerization of styrene-butadiene rubber (SBR) is used as the example system.     

Synthesis and property of polystyrene particle with smart surface by emulsion polymerization using “giant” surfactant

The colloidal particles with switchable surfaces (i.e. smart surfaces) have attracted great attention for numerous potential industrial applications. We report here a novel approach for the fabrication of polymeric particles with smart surfaces by emulsion polymerization using “giant” surfactant. Specifically, the “giant” surfactant was obtained by incorporating poly(4-vinylpyridine) chains onto the one bulb of snowman-shaped polystyrene particles, and then used as emulsifier for the emulsion polymerization at pH = 2.00. The nearly monodisperse waxberry-like polystyrene particles were prepared with dual-size roughness surfaces, and the particulate film exhibited reversibly pH-switchable superhydrophobic property due to the pH-sensitivity of P4VP chains and the surface topology. This property enabled the particles could be used to effectively sequester hazardous anions from the wastewater.     

种子乳液聚合法制备纳米SiO_2/苯丙复合乳液

采用种子乳液聚合工艺,用经硅烷偶联剂改性后的纳米SiO2原位合成了纳米SiO2/苯丙复合乳液。通过正交实验确定了最佳原料配比和聚合工艺条件,并对复合乳液性能进行了分析与表征。结果表明,当功能单体的用量为单体总量的5%、阴离子乳化剂十二烷基硫酸钠(SDS)与非离子乳化剂辛基苯基聚氧乙烯醚(OP-10)质量比为1颐1、复合乳化剂总量3%、纳米SiO2含量为单体总量的1.5%、聚合温度为80℃时,可制备具有良好综合性能的复合乳液,其涂膜耐水性、硬度、附着力等均优于普通苯丙乳液。该复合乳液乳胶粒粒度呈单峰分布,平均粒径为101nm,具有核/壳结构。     

New green surfactants for emulsion polymerization

Nonylphenol ethoxylates (NPEOs) are widely used as surfactants for emulsion polymerization and for post adding stabilization for latex applications in formulations with high filler content. However, the current exposure situation of NPEOs in Europe gives rise to environmental concern, despite of the fact that some industry associations have already pro-actively taken measures to phase out these chemistry of their products, e.g. the European detergent industry (AISE) by a voluntary commitment. As a consequence, the EU Commission has recommended to implement a risk reduction strategy, which foresees the ban of all applications leading to direct emissions to waste water and strict emission controls for all other technical processes using NPEOs as surfactant. The effectiveness of the risk reduction measures will be monitored by the authorities. In case that the environmental concentrations of NPEOs and their metabolites do not decrease by at least 70 percent, additional risk reduction measures for technical applications are planned. In one of the major fields of application, alkyl phenol-free emulsifiers with a more favorable ecological profile are becoming key ingredients for eco-friendly emulsion polymers and polymer dispersions: the Disponil^® AFX-Series (Cognis) is a NPEO-free surfactant system for emulsion polymerization and polymer dispersant also as a supposition for getting the European eco-label for indoor paints and varnishes.

These new non-ionic surfactant system exhibits an effective performance during polymerization and as post reaction stabilizers. These products are environmentally compatible, mostly derived from natural renewable resources and readily biodegradable. The underlying chemistry is in compliance with relevant indirect food contact applications [BfR recommendations, respectively, FDA CFR 21 (federal drug administration)], and a dossier to register the surfactants in the positive list of the EU Directive 2002/72/EC for application in plastic has recently been submitted.

Clear, high solid liquids at room temperature, these surfactants are easy to handle and very effective with regard to controlling particle size, film properties and overall latex stability. This paper summarizes their chemical and surface properties, as well as their performance in model emulsion polymerization formulations for architectural coatings.     

反相乳液聚合合成聚丙烯酰胺

以甲苯为介质,Span80/Span20为乳化剂,叔丁基过氧化氢/亚硫酸氢钠氧化还原体系为引发剂,采用反相乳液聚合制备了分子量高达9.4×106的聚丙烯酰胺乳液。研究了乳化剂种类及用量、引发剂种类及用量、油水比、单体浓度,反应温度对共聚物相对分子量、聚合转化率以及聚合反应速率的影响。其最佳聚合配方及工艺条件为:油水体积比为1.4,单体浓度30%,引发剂用量0.003%,乳化剂用量12%,聚合温度30℃。