Synthesis of Molecularly Imprinted Polymer Particles by Suspension Polymerization in Silicon Oil

Molecular imprinting is a method to prepare polymers with recognition site of desired and predetermined selectivity1. Molecularly imprinted polymers (MIP) are prepared by copolymerizing functional and cross-linking monomers in the presence of a molecular …     

Preparation of Composite Polymer Particles by Seeded Dispersion Polymerization in Ionic Liquids

Summary: Submicron-sized monodisperse PS particles were prepared by dispersion polymerization of styrene in ionic liquids with poly(vinylpyrrolidone) as stabilizer. Seeded dispersion polymerization of MMA was subsequently carried out with PS seeds in [Bmim][BF₄] to prepare PS/PMMA composite particles. Observation of the obtained particles of ultrathin cross-sections with a scanning and transmission electron microscope revealed that no secondary nucleation occurred during the seeded dispersion polymerization and that the particles have a core-shell morphology consisting of a PS core and a PMMA shell. Successful preparation of PS/PMMA composite particles in an ionic liquid has thus been demonstrated. Moreover, PS/PAA (PS-core/PAA-shell) composite particles were prepared by seeded dispersion polymerization in [DEME][TFSI], illustrating that hydrophobic/hydrophilic composite particles can be readily prepared in the ionic liquid.     

Magnetic Polymer Composite Particles Via In situ Inverse Miniemulsion Polymerization Process

We aimed at preparing magnetic iron oxide particles by the oxidation-precipitation method in order to encapsulate these particles in polymer matrices composed of poly(acrylamide-styrene sulfonic acid sodium salt). Nanocomposites were synthesized by the incorporation of surface treated magnetic nanoparticles in the synthesized polymers via in situ inverse mini-emulsion polymerization process. The study parameter was the ionic monomer content in the synthesized polymers. The structure and the morphology of the magnetic nanogels were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM). FTIR and XRD showed that pure magnetite was formed and successfully encapsulated in the composite nanoparticles. The polymer encapsulation could reduce the susceptibility to leaching and could protect the magnetite particle surfaces from oxidation. The ionic monomer content had a great effect on the magnetization behavior. Magnetite prepared by the oxidation precipitation method, of 50 nm mean particle size, was embedded successfully into the polymer nanogels with a reasonable magnetic response, as proved by vibrating sample magnetometer measurement. Magnetic nanocomposites were proven to be super-ferromagnetic materials.     

种子聚合法制备非球形聚合物颗粒的研究进展

十年前,光子晶体的需求促进了非球形颗粒的研究热潮。非球形颗粒由于其对称性下降,带来了新的性能和应用前景,成为当前材料领域研究的热点,得到了较广泛研究,目前其制备方法包括种子聚合法、自组装法、粒子聚集法、微流体法和机械拉伸法等。本文简述了种子聚合法的发展历程,介绍了种子聚合法制备非球形聚合物颗粒的相关机理,以种子微球材质分类综述了种子聚合法制备非球形聚合物颗粒的形貌和结构控制技术进展,概述了其潜在的应用领域,展望了可能的发展趋势。     

Magnetic Molecularly Imprinted Polymer Particles Synthesized by Suspension Polymerization in Silicone Oil

Summary: Magnetic nanoparticles have been prepared by a co‐precipitation method and modified with methacryloxypropyltrimethoxysilane. Magnetic molecularly imprinted polymer particles have been prepared by suspension polymerization in silicone oil. The particles possess a high affinity to the template molecules and are rapidly separated under a magnetic field.

SEM photograph of magnetic MIP particles.     

Preparation of Polystyrene Particles by Dispersion Polymerization in an Ionic Liquid

Submicron‐sized monodisperse polystyrene (PS) particles were successfully prepared by dispersion polymerization of styrene in an ionic liquid, N,N‐diethyl‐N‐methyl‐N‐(2‐methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide ([DEME][TFSI]) at 70 °C with poly(vinyl pyrrolidone) (PVP) as a stabilizer. At the optimum PVP and styrene concentrations with regard to preparation of stable polymer particles, the number‐average diameter and coefficient of variation were 350 nm and 5.7%, respectively. The particle size increased with a decrease in the PVP concentration and an increase in the styrene concentration. Moreover, we succeeded in producing PS particles by thermal polymerization in the absence of a radical initiator at 130 °C in [DEME][TFSI] using a conventional reactor (not autoclave) utilizing the advantages of non‐volatility and thermal stability of the ionic liquid.

     

The Effect of Cyclodextrins in Polymer Particles Synthesis

The free radical polymerization of styrene in water in the presence of β-cyclodextrin (β-CD) is described.It is found that β-CD could greatly accelerate the polymerization,enhance the final conversion of monomer.The particle-size distribution of the final polymer is also improved than that without β-CD in the system.     

In Situ Incorporation of Doxorubicin in Copolymer Particles During Suspension Polymerization

Summary: This work reports the kinetic behavior and the molecular properties of obtained copolymers during vinyl acetate and methyl methacrylate suspension copolymerizations in presence of doxorubicin. The obtained spherical particles are intended for use as chemoembolization agents. It is shown that the presence of doxorubicin in the reaction medium promotes significant changes in the copolymerization kinetics and final molecular weight averages of the polymer product.     

Synthesis of Very Small Polymer Particles by Catalytic Polymerization in Aqueous Systems

The preparation of aqueous dispersions of very small particles (size < 30 nm) of various polymers (polyethylenes, stereoregular 1,2-polybutadiene, and polyalkenamers) by catalytic polymerization with a water-soluble catalyst, or with microemulsions of lipophilic catalysts is reviewed.     

Microspheres Sensor Based on Molecularly Imprinted Polymer Synthesized by Precipitation Polymerization

IntroductionSincethepiezoelectricbulkacousticwave (BAW)sen sorswereappliedinliquidphaseinthe 1980s ,manypapershavebeenreported .1,2 However,theapplicationofBAWsen sorsbasedonmasseffectislimitedbecauseoflackofthespecialselectivitytotheanalyte.Variousmethodshavebeenproposedtosolvethisproblem ,especiallytheapplicationofthebiomaterials .3Unfortunately ,theresultwasnotsogoodasexpected,duetotheinstinctdisadvantageofthebiomateri als ,e.g .,poorstability ,shortlifespan ,althoughpossess inghighselec…     

Shaping Polymer Particles by Carbon Nanotubes

We report the formation of poly(propylene) spherical and ellipsoidal particles templated by carbon nanotubes via solution crystallization. With an increase in nanotube loading, the particle shape changes from sphere to ellipsoid. In the intermediate concentration range, both spherical and ellipsoidal shapes coexist. The particle size decreases with an increase in nanotube loading.

     

Synthesis of Poly(methyl methacrylate) Nanosize Particles by Differential Microemulsion Polymerization

Poly(methyl methacrylate) nanosize particles were synthesized by a differential microemulsion polymerization process. Sodium dodecylsulfate and ammonium persulfate were used as the surfactant and initiator, respectively. The effects of reaction conditions on the particle size have been investigated. A particle size of less than 20 nm in diameter has been achieved with surfactant/monomer and surfactant/water weight ratios of 1:18 and 1:120, i.e. much milder conditions than those previously reported in the literature.

TEM image of nanoparticles prepared via differential microemulsion polymerization.     

浓乳液双相聚合方法制备异形聚合物粒子

采用浓乳液双相聚合方法,成功制备了聚丙烯酸丁酯(PBA)的异形粒子,通过在连续相中引入聚合物隔层,大大提高了浓乳液聚合过程中的稳定性,探讨了隔层种类对浓乳液稳定性的影响,并研究了浓乳液分散相体积分数和交联剂用量对PBA粒子异形程度的影响,并结果表明,浓乳液双相聚合过程中,分散相体积分数越高,交联剂用量越高,PBA粒子的异形程度越大。     

Preparation of Bowl-Like Polymer Particles via Multi-Step Emulsion Polymerization and Alkali Post-Treatment

Summary : Monodisperse P(BA-MMA-MAA-EGDMA)/P(St-MAA-DVB) core/shell latex particles were first synthesized by a four-step emulsion polymerization, and a new kind of latex particles with “bowl-like” morphology were obtained by post-treating the resultant core/shell particles under alkali condition. Results indicated that the feeding rates of the monomer mixture and initiator aqueous solution were the key parameters to obtain monodisperse core/shell latex particles in the emulsion polymerization process, and the latex particles with “bowl-like” morphology could be generated only when the treatment temperature was equal or higher than 70 °C.     

聚合物/水两相界面自由基引发聚合制备不对称粒子

报导了一种新的制备不对称粒子的简单方法. 首先, 利用旋转涂膜法在云母片表面涂上一层聚4-乙烯基吡啶(P4VP)薄膜, 并且P4VP薄膜中分散有自由基引发剂偶氮二异丁腈(AIBN)和二乙烯基苯(DVB); 然后将云母片插入溶解有N-异丙基丙烯酰胺(NIPAM)的水溶液, 在氮气保护下升高温度, 实施自由基聚合. 聚合起始阶段, AIBN分解的自由基主要是在P4VP薄膜中引发DVB聚合. 由于相分离, DVB聚合后形成的PDVB在P4VP中形成粒子. 随着聚合的进行, 由于PDVB粒子的不断长大或向水/P4VP界面迁移, 使得粒子的一侧暴露在水相中. 在界面上, PDVB粒子上的大分子自由基或AIBN新分解产生的自由基与PDVB中剩余双键继续反应形成的大分子自由基引发水相中的NIPAM反应, 从而在粒子的一侧形成PNIPAM接枝; 而PDVB粒子的另一侧则嵌在P4VP膜中, 不会参加接枝反应. 最后, 实施与P4VP层分离后即可得到两亲性的PDVB-PNIPAM不对称粒子.     

分散聚合法合成磁性高分子微球

在磁流体存在下,以聚乙二醇(w=4000)为分散剂,乙醇/水为分散介质,进行苯乙烯—丙烯酸—二乙烯基苯的分散聚合,合成具有磁核的聚苯乙烯微球。磁性聚苯乙烯微球的红外光谱显示出磁性氧化铁的特征吸收峰(580cm~(-1)),微球内部磁性氧化铁含量可控制,500-4000μg/g之间。考察了磁流体、聚乙二醇、分散介质和丙烯酸对微球磁响应性和粒径的影响。合成了粒径为1-10μm的磁性高分子微球。     

Modification of Cross-Linked Rubber Particles by Free Radical Polymerization

The synthesis of polystyrene chains covalently bound to the surface of cross-linked rubber particles from recycled tires (ground tire rubber, GTR) was investigated via free radical polymerization in situ by using azobisisobutyronitrile (AIBN) and dibenzoyl peroxide (BPO) as initiators. Indeed, the graft polymerization provides a significant route to modify the physical and chemical properties of these particles allowing to improve their compatibility with other polymers. Polymerization reactions were carried out in bulk by changing the styrene/GTR ratio as well as the amount of free radical initiator. Appreciable amounts of polystyrene (PS) were grafted on GTR when BPO was used as confirmed by particle characterizations.     

Polymer Brushes by Nitroxide‐Mediated Polymerization

This review article describes the preparation of polymer brushes by nitroxide‐mediated radical polymerization using either the ‘grafting to’ or the ‘grafting from’ approach. The use of TEMPO as a classical initiator is intensively described. More sophisticated nitroxides are also included in the discussion. Brush formation on flat surfaces such as wafers and also on particles is reported. Finally, some applications of polymer brushes are presented.

     

种子溶胀法制备单分散高交联聚苯乙烯微球

以分散聚合法制得平均粒径为1.80μm的聚苯乙烯微球为种子,与溶胀剂和单体、交联剂的混合物经二步溶胀聚合法,制备了单分散高交联聚苯乙烯微球。讨论了单体浓度和醇水比对种球的影响,以及溶胀剂的种类、溶胀剂浓度、交联剂浓度、溶胀温度和搅拌速度等因素对交联聚苯乙烯微球粒径及分散系数的影响。用扫描电子显微镜、离心式粒度分析仪及DSC分析测试技术对微球的外观形貌、粒径大小及分布和玻璃化转变温度分别进行了表征。结果表明,当溶胀剂质量分数为25%、交联剂质量分数为23%、溶胀温度30℃、搅拌速度为150r/min时,可制得平均粒径为6.20μm且单分散性较好的高交联聚苯乙烯微球。