Preparation of polystyrene/clay nanocomposite by suspension and emulsion polymerization

Organophilic montmorillonite was prepared using ion‐exchange method between sodium ions in clay layers and four kind of quaternary ammonium salt. The montmorillonite has the largest d₀₀₁‐spacing, as determined by X‐ray diffraction in modified by di(hydrogenated tallowalkyl) dimethyl ammonium chloride. Polystyrene montmorillonite nanocomposites were obtained by suspension and emulsion polymerization of styrene in the dispersed organophilic montmorillonite. The d₀₀₁‐spacing of clay was determined by X‐ray diffraction (XRD). The thermal stability of organophilic montmorillonite was investigated by thermogravimetric analysis (TGA). POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

In situ preparation of Mg(OH)2/polystyrene nanocomposite via soapless emulsion polymerization

Magnesium hydroxide nanoneedles modified by oleic acid [OA–Mg(OH)₂] were synthesized via alkaline injection into magnesium chloride solution in the presence of oleic acid (OA). The magnesium hydroxide/polystyrene nanocomposite [Mg(OH)₂/PS] was then prepared by soapless emulsion polymerization technique in an aqueous suspension. The Fourier transform infrared (FT–IR) analysis shows that the polystyrene was covalently grafted onto the surfaces of the Mg(OH)₂nanoneedles [OA–Mg(OH)₂]. The dispersion of Mg(OH)₂nanoneedles in polystyrene is uniform as observed by transmission electron microscope (TEM). The grafting percentage was determined by means of elemental analysis (EA). The thermal behavior determined by the differential scanning calorimetry (DSC) indicated that Mg(OH)₂/PS had a higher glass transition temperature than PS matrix, and it can be concluded that Mg(OH)₂ could retard the degradation of PS based on the data of thermal gravimetric analysis (TGA) and differential thermoanalysis (DTA).     

The preparation of uniform polystyrene latices by true emulsion polymerization

Conventional emulsion polymerization of styrene produces some polydispersion in particle sizes in the latex. By carrying out a one-stage polymerization of finely emulsified monomer droplets of styrene formed in a mixture of methanol and water, it is possible to prepare stable latices of polystyrene in which the particles are perfectly uniform in size. The polymer has a relatively low molecular weight, but it is more stable to fragmentation by surfactant solutions than polystyrene prepared by conventional emulsion polymerization, the molecular weight of which is greater. The surface charge density of the particles is higher than that of particles produced by emulsion polymerization, and this probably accounts for the stability of the dispersion during polymerization and of the latex.     

无皂乳液聚合法合成单分散性阴离子聚苯乙烯微球

采用无皂乳液聚合法制备了粒径大小可控且均一的聚苯乙烯微球,研究了反应过程中SDS加入量、反应温度、引发剂加入量及反应介质对聚苯乙烯微球粒径大小及分布的影响。利用傅立叶变换红外光谱仪对微球结构进行了表征。     

Synthesis and characterization of polyvinyl acetate/montmorillonite nanocomposite by in situ emulsion polymerization technique

Exfoliated polyvinyl acetate/montmorillonite nanocomposite (PVAc/MMT) was prepared via in situ emulsion polymerization. The resulting PVAc with various organophilic MMT contents was investigated. In the nanocomposite latex preparation, sodium lauryl sulfate (SLS), ammonium persulfate (APS), and poly (vinyl alcohol) (PVA) are used as anionic emulsifier, conventional anionic initiator, and stabilizer, respectively. The samples were characterized using elemental analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM). The XRD and AFM results demonstrate that the MMT well dispersed at molecular level in the PVAc matrix. Thermal properties of the nanocomposite were studied by using differential scanning calorimetric analysis (DSC). The exfoliated PVAc/MMT nanocomposite showed a higher glass transition temperature and a better thermal stability compared to the pure PVAc.     

硝基苯对傅克酰基化反应制备羧基化聚苯乙烯的影响

在常用的傅克反应溶剂二氯甲烷中添加另一种傅克反应溶剂硝基苯,且酰基化试剂邻苯二甲酸酐(PA)与硝基苯的摩尔比为1时,可大大提高PA的转化率.研究发现,作为傅克酰基化反应的常用溶剂,二氯甲烷和硝基苯的作用是不同的,硝基苯可能参与了傅克酰基化反应的中间过程;研究还发现,硝基苯的加料方式对反应结果的影响,与PA与硝基苯的摩尔比例有关.通过傅克酰基化反应制备了羧基化交联聚苯乙烯微球.     

相反转法合成一种水性环氧树脂乳液的研究

用环氧树脂E-44和表面活性剂OP-10合成水性环氧树脂乳化剂,然后在表面活性剂的作用下,采用相反转法,将油包水状态环氧树脂转化成水包油状态的水性环氧树脂。探讨了乳化剂用量、反应温度等对水性环氧树脂粒径和结构的影响。结果表明,合成水性环氧树脂的最佳工艺条件是:以三乙醇胺为催化剂,乳化剂用量为20%时,反应温度为60℃,反应时间为6 h。     

无机-有机纳米复合乳液的原位聚合及其应用

综述了原位乳液聚合法制备无机．有机纳米复合乳液的技术现状及其形成机理，并运用此技术合成了舍无机纳米粒子的压敏胶用无机-有机纳米复合乳液，分析了纳米粒子在制备过程中的分散性能，从纳米粒子引入方式、乳化剂用量、纳米粒子加入量3方面对压敏胶性能进行考查。     

Ion exchange with irreversible reaction in deep fluidized beds

The exchange of CI^? ion between dilute aqueous solutions of hydrochloric acid and the ion exchange resin IRA-425 in fluidized beds was studied in a laboratory size column. Analysis of the experimental data showed that axial mixing of particles in deep beds was incomplete and also that packed and fluidized bed break-through curves were similar. A model is proposed describing the bed as a series of mixing stages for solids with axially dispersed flow of liquid. Data are presented in support of such a concept. An empirical method is proposed for prediction of the break-through curves at various operating conditions, requiring only a very limited amount of experimentation.     

Polymericaly modified clays to preparation of polystyrene nanocomposite by nitroxide mediated radical polymerization and solution blending methods

Polymericaly modified clays that contain an oligomeric poly(styrene‐co‐chloromethyl styrene) ammonium salt have been prepared and used to preparation of polystyrene (PS) nanocomposites. First, PS and poly(styrene‐co‐chloromethyl styrene) [P(St‐co‐CMSt)] were synthesized by nitroxide mediated living free radical polymerization (NMRP) by TEMPO iniferter .Then the copolymer was coupled with N, N‐dimethyl hexadecyl amine to prepare polymeric modifier by anion exchange of chlorine group of chloromethyl styrene (CMSt) by quaternary amine. The synthesized polymeric modifier was mixed with nanoparticle of silica to change the property of clay surface from hydrophilic to hydrophobic via cation exchange of Na⁺ with alkylammonium ions. For synthesizing of nanocomposites, we used polymericaly modified montmorillonite and PS that was synthesized by NMRP technique. Intercalated nanocomposites and in some cases, exfoliated or mixed intercalated/exfoliated nanocomposites of all of these polymers have been produced by solution blending method. The prepared materials were characterized by X‐ray diffraction, Transmission electron microscopy, Fourier‐transform infrared, ¹H nuclear magnetic resonance, and gel permeation chromatography techniques. Effect of layered silicates on thermal properties and glass transition temperature of PS was investigated using TGA and DSC techniques. POLYM. COMPOS., 38:1127–1134, 2017. © 2015 Society of Plastics Engineers     

Surface modification of montmorillonite with novel modifier and preparation of polystyrene/montmorillonite nanocomposite by in situ radical polymerization

Exfoliated polystyrene/organo-modified montmorillonite nanocomposite was synthesized through in situ free radical polymerization by dispersing a modified reactive organophilic montmorillonite layered silicate in styrene monomers. The original montmorillonite (MMT) was modified by a novel cationic surfactant. A cationic initiator, consisting of a quaternary ammonium salt moiety, α-phenyl chloro acetyl chloride moiety, and 9-decen-1-ol moiety, was intercalated into the interlayer spacing of the layered silicate. Modified MMT clays were then dispersed in styrene monomers and subsequently polymerized by a free-radical in situ polymerization reaction to yield polystyrene/montmorillonite nanocomposite. The structure of obtained modifier was investigated by proton nuclear magnetic resonance (¹H NMR) and Fourier-transform infrared (FT-IR) spectroscopy. The exfoliating structure of nanocomposite was probed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Comparing with pure polystyrene, the nanocomposite showed much higher decomposition temperature and higher glass transition temperature (T_g).     

Toughened polystyrene composites by the concentrated emulsion pathway

Rubber–styrene solutions of various compositions and containing a suitable initiator have been polymerized starting from concentrated emulsions in which the above solutions constitute the dispersed phase and solutions of sodium dodecylsulfate in water the continuous phase. Latexes of rubber-modified polystyrene composites have been thus obtained. Solutions of rubber–styrene have been also polymerized by bulk polymerization for comparison purposes. The molecular weights have been determined from intrinsic viscosity measurements, and the mechanical properties of the composites have been studied via tensile testings. Because of the lower mobility of the high-molecular radicals in the concentrated emulsions, higher molecular weights have been obtained by the concentrated emulsion polymerization than by the bulk polymerization method. The tensile properties and toughness of the composites have been determined. While the two polymerization methods provide high, comparable toughness, the concentrated emulsion method generates latexes that can be easily processed in any desirable shape. © 1994 John Wiley & Sons, Inc.     

无皂乳液聚合制备多孔聚苯乙烯纳米微球

苯乙烯(St)单体、过硫酸钾(KPS)和二乙烯基苯(DVB)通过无皂乳液聚合,在70℃下反应8 h,合成聚苯乙烯(PS)纳米粒子,PS磺化,得到磺化聚苯乙烯(SPS),通过正庚烷和乙醇溶胀后,水进入粒子内部发生相分离,形成多孔聚苯乙烯PS,在-30 k Pa负压条件下,负载缓蚀剂苯丙三氮唑(BTA)。考察单体量和反应时间对粒子形态的影响。结果表明,采用10 g St,0.05 g KPS,100 mL去离子水,反应2 h后加入0.05 g DVB,可以得到粒径合适、球形完整的PS纳米微球。PS微球磺化6 h,n(乙醇)∶n(水)∶n(正庚烷)=5∶5∶1,造孔10 h时,可得到形貌和孔径合适的多孔SPS纳米微球。SEM、TEM和FTIR表明,多孔SPS微球表面和内部负载上了一定量的缓蚀剂BTA。     

Synthesis and characterization of PS-clay nanocomposite by emulsion polymerization

Summary Polystyrene-Na⁺-montmorillonite(PS-Na⁺-MMT) nanocomposites are prepared by a simple emulsion polymerization. The X-ray diffraction(XRD) and infrared spectroscopy (IR) analysis confirm that polystyrene(PS) macromolecules can be inserted between lamella layers and whose layer separation is consequently higher than in the polymer-free clay. The enhanced thermal properties of composites are measured by differential scanning calorimetry(DSC) and thermogravimetric analysis(TGA) thermogram and indicate that the glass transition and the decomposition onset temperature of obtained nanocomposites are found to be moved to the higher temperature region. The increased Young's modulus of the obtained nanocomposites is ascribed to the intercalation of PS in clay galleries as well as the fine dispersion of clay particles into the polymer matrix. Received: 23 February 1999/Revised version: 26 March 1999/Accepted: 1 April 1999     

The thermal degradation of polystyrene nanocomposite

Nanocomposite formation brings about an enhancement of many properties for a polymer, including enhanced fire retardancy. This study was carried out to determine if the presence of clay causes changes in the degradation pathway of polystyrene. In the case of virgin PS, the degradation pathway is chain scission followed by β-scission (depolymerization), producing styrene monomer, dimer and trimer, through an intra-chain reaction. As the clay loading is increased, the evolved products produced through inter-chain reactions become significant. Due to the barrier effect of the clay layers, the radicals have more opportunity to undergo radical transfer, producing tertiary radicals, and then radical recombination reactions, producing head-to-head structures, and hydrogen abstraction from the condensed phase also occurs. In the presence of clay, the color of solid residues darkens as the clay content increases. It is thought that this color change is caused by the formation of conjugated double bonds in the presence of clay.     

无皂乳液聚合反应机理和制备方法的研究进展

介绍了无皂乳液聚合的反应机理,包括成核机理和核增长机理;概括了无皂乳液聚合的方法及最新研究进展。     

The preparation and properties of polystyrene/functionalized graphene nanocomposite foams using supercritical carbon dioxide

In this work, polystyrene (PS)/functionalized graphene nanocomposite foams were prepared using supercritical carbon dioxide. Thermally reduced graphene oxide (TRG) and graphene oxide (GO) were incorporated into the PS. Subsequently, the nanocomposites were foamed with supercritical CO₂. The morphology and properties of the nanocomposites and the nucleation efficiency of functionalized graphene in foaming PS are discussed. Compared with GO, TRG exhibited a higher nucleation efficiency and more effective cell expansion inhibition thanks to its larger surface area and better exfoliated structure. It is suggested that the factors that have a significant influence on the nucleation efficiency of TRG and GO originate from the differences in surface properties and chemical structure. Furthermore, PS/TRG nanocomposites and their nanocomposite foams also possess good electrical properties which enable them to be used as lightweight functional materials.© 2012 Society of Chemical Industry     

Effects of acrylonitrile content on the properties of clay-dispersed poly(styrene-co-acrylonitrile) copolymer nanocomposite

Summary Clay-dispersed nanocomposites have been prepared by simple melt-mixing of two components, i.e. poly(styrene-co-acrylonitrile) copolymers with different contents of acrylonitrile comonomer and two different kinds of organophilic clay (Cloisite? 25A and Cloisite? 30A), with a twin screw extruder. Dispersion behavior of 10-?-thick silicate layers of clay in the nanocomposites was investigated by using an X-ray diffractometer and a transmission electron microscope. It was found that acrylonitrile comonomer incorporated into poly(styrene-co-acrylonitrile) copolymers accelerates intercalation of the copolymers into the galleries of silicate layers modified with an organic intercalant. The faster intercalation of a matrix polymer leads to the better dispersion of silicate layers in the matrix polymer. Received: 1 May 2000/Revised version: 10 July 2000/Accepted: 24 July 2000     

掺氮TiO_2纳米颗粒稳定的Pickering乳液制备及其触发酶反应

利用烷基硅烷接枝的掺氮TiO_2纳米颗粒稳定W/O型Pickering乳液,研究了TiO_2掺氮量对成乳的影响以及乳液的可见光响应性能,并将其作为微反应器应用于触发脲酶催化尿素生成碳酸铵的反应中。结果表明:在可见光照射下,烷基硅烷接枝的掺氮TiO_2纳米颗粒表面由疏水变为亲水,可引发乳液液滴聚并以及液滴内酶促反应发生。