共查询到20条相似文献,搜索用时 15 毫秒
1.
Kyung Min Do Haldorai Yuvaraj Min Hee Woo Hyun Gyu Kim Euh Duck Jeong Keith P. Johnston Kwon Taek Lim 《Colloid and polymer science》2008,286(11):1343-1348
A novel synthetic route to prepare polystyrene/SiO2 composite microparticles in supercritical carbon dioxide (scCO2) is presented. Silica particles with the size of 130 nm which were surface-modified with 3-(trimethoxysilyl) propyl methacrylate
were used as seeds in the dispersion polymerization of styrene in the presence of a polymeric stabilizer, poly(1,1-dihydroheptafluorobutyl
methacrylate-co-diisopropylaminoethyl methacrylate) to produce dry composite particles. The transmission electron microscopy analysis revealed
that the composite microspheres contained several silica particles. 相似文献
2.
Reversible addition-fragmentation chain transfer (RAFT) functionalities were anchored to the exterior surface of mesoporous silica nanoparticles (MSNs) without changing the mesoporous structure, RAFT polymerization of styrene was subsequently conducted to graft polystyrene (PSt) onto the exterior surface of MSNs, forming a novel core-shell nanostructure with a mesoporous core and a polymer nanoshell. Fourier transform infrared spectroscopy (FT-IR), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) were used to characterize the produced mesoporous core-shell nanostructure, the results showed that the thickness of the nanoshell increased with the increasing time of polymerization. 相似文献
3.
A. M. Shanmugharaj Won Seok Choi Sung Hun Ryu 《Journal of polymer science. Part A, Polymer chemistry》2010,48(22):5092-5099
Zinc antimonate nanoparticles consisting of antimony and zinc oxide were surface modified in a methanol solvent medium using triethoxysilane‐based atom transfer radical polymerization (ATRP) initiating group (i.e.,) 6‐(2‐bromo‐2‐methyl) propionyloxy hexyl triethoxysilane. Successful grafting of ATRP initiator on the surface of nanoparticles was confirmed by thermogravimetric analysis that shows a significant weight loss at around 250–410 °C. Grafting of ATRP initiator onto the surface was further corroborated using Fourier transform Infrared spectroscopy (FT‐IR) and X‐ray photoelectron spectroscopy (XPS). The surface‐initiated ATRP of methyl methacrylate (MMA) mediated by a copper complex was carried out with the initiator‐fixed zinc antimonate nanoparticles in the presence of a sacrificial (free) initiator. The polymerization was preceded in a living manner in all examined cases; producing nanoparticles coated with well defined poly(methyl methacrylate) (PMMA) brushes with molecular weight in the range of 35–48K. Furthermore, PMMA‐grafted zinc antimonate nanoparticles were characterized using Thermogravimetric analysis (TGA) that exhibit significant weight loss in the temperature range of 300–410 °C confirming the formation of polymer brushes on the surface with the graft density as high as 0.26–0.27 chains/nm2. The improvement in the dispersibility of PMMA‐grafted zinc antimonate nanoparticles was verified using ultraviolet‐visible spectroscopy and transmission electron microscopy. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
4.
Narrow- or monodisperse core-shell polymer microspheres with a dense core and a lightly crosslinked shell with different functional groups, such as ester, hydroxyl, cyano, were prepared by two-stage distillation-precipitation polymerization without any stabilizer. Commercial divinylbenzene (DVB), containing 80% of DVB was polymerized by distillation-precipitation polymerization with 2,2′-azobis(2-methyl propionitrile) (AIBN) as initiator in neat acetonitrile in the absence of any stabilizer as the first stage polymerization and used as the core. When the conversion of DVB was about 35% in the first stage, the second-comonomers with different functional groups, such as methyl methacrylate (MMA), ethyl methacrylate (EMA), butyl methacrylate (BMA), 2-hydroxyethyl methacrylate (HEMA), i-octyl acrylate (i-OA), dodecyl acrylate (DA), methyl acrylate (MA), ethyl acrylate (EA), ethylene glycol dimethacrylate (EGDMA), triethyleneglycol dimethacrylate (TEGDMA), trimethylolpropane trimethacrylate (Trim), and acrylnitrile (AN) together with AIBN were introduced, respectively, into the reaction system and copolymerized with unreacted DVB on the core surface to form a lightly crosslinked functional shell. The resulting core-shell polymer particles were characterized with scanning electron microscopy (SEM) and FT-IR spectra. 相似文献
5.
CHEN Zhijun ZHOU Sikai LU Wenzhong FANG Shaoming JIANG Xiqun & YANG Changzheng . College of Materials Chemical Engineering Zhengzhou University of Light Industry Zhengzhou China . Laboratory of Mesoscopic Material Science Department of Polymer Science & Engineering College of Chemistry & Chemical Engineering Nanjing University Nanjing China 《中国科学B辑(英文版)》2005,48(5):449-458
Manipulation of surface properties of wafer is im- portant in technologies of biotechnology and advanced microelectronics[1,2]. A number of methods have been developed to modify the surface properties[3]. Among them, polymer brush is a well recognized met… 相似文献
6.
Nagase K Mizutani Akimoto A Kobayashi J Kikuchi A Akiyama Y Kanazawa H Okano T 《Journal of chromatography. A》2011,1218(48):8617-8628
Poly(N-isopropylacrylamide) (PIPAAm) brush grafted silica beads, a thermo-responsive chromatographic stationary phase, were prepared through a surface-initiated atom transfer radical polymerization (ATRP) using 2-propanol, N,N-dimethylformamide (DMF), and water as reaction solvents. The rate of grafting PIPAAm on silica bead surfaces was different and found to be dependent on the reactivity of reaction solvent. Temperature-dependent elution profiles of hydrophobic steroids from the prepared-beads-packed columns were found to be different, although the graft amounts of PIPAAm were similar on silica bead surfaces. Especially, prepared beads using 2-propanol exhibited a higher resolution than those using DMF. Calibration curves using glucose and pullulan suggested that beads prepared using DMF prohibited analytes to diffuse into the pores. On the contrary, beads prepared using 2-propanol allowed analytes to diffuse into the pores. The pore diameter of the prepared beads, measured by N(2) adsorption-desorption measurement, suggested that beads using 2-propanol has relatively larger pore diameter than those using DMF. Thus, the reaction solvent in surfaces-initiated ATRP affected the grafting configuration of PIPAAm on porous silica-bead surfaces, leading to the different separation efficiency of stationary phase for bioactive compounds. 相似文献
7.
Polystyrene core microspheres of narrow-size distribution were prepared by dispersion polymerization of styrene in a mixture
of ethanol and 2-methoxy ethanol. Polystyrene/polychloromethylstyrene and polystyrene/poly(chloromethylstyrene-divinylbenzene)
core-shell microspheres of narrow-size distribution were prepared by seeded emulsion polymerization of chloromethylstyrene
or chloromethylstyrene and divinylbenzene in the presence of the polystyrene core microspheres at 71 °C. Core-shell particles
with different properties (size, surface morphology, and composition) have been prepared by changing various parameters belonging
to the emulsion polymerization process, e.g., volume of the chloromethylstyrene and the volume ratio of chloromethylstyrene
to divinylbenzene. Dissolution of the polystyrene core of the polystyrene/poly(chloromethylstyrene-divinylbenzene) core-shell
particles resulted in the formation of crosslinked hollow polychloromethylstyrene microspheres, broken crosslinked polychloromethylstyrene
shells, or particles containing voids, depending on the composition of the polystyrene/poly(chloromethylstyrene-divinylbenzene)
particles. 相似文献
8.
Polytetrafluoroethylene (PTFE)/polyacrylate core-shell nanoparticles were produced via the emulsifier-free seeded emulsion
polymerization of acrylate monomers with PTFE latex as seed. The monomer conversions under different synthesis parameters
were monitored by a gravimetric method. The polymerization conditions for preparing PTFE/polyacrylate core-shell nanoparticles
were surveyed and optimized. The chemical component of the PTFE/polyacrylate particles was confirmed by comparing the Fourier-transform
infrared spectra of PTFE and PTFE/polyacrylate particles. The core-shell structure of the resulting PTFE/polyacrylate nanocomposite
particles was investigated by transmission electron microscopy. The water contact angles of the films prepared from PTFE/polyacrylate
nanocomposite particles showed that the films were hydrophilic, which confirmed that polyacrylate covered the surface of the
PTFE particles. This kind of PTFE/polyacrylate core-shell nanoparticles might advance the compatibility of PTFE with other
materials due to the covering of the polyacrylate shell on the surface of PTFE, which would make them promising in various
fields. 相似文献
9.
Vincent Ladmiral 《European Polymer Journal》2009,45(10):2788-8953
Monodisperse zinc sulfide (ZnS) particles of diameters ranging from 120 to 400 nm were prepared and then coated with a thin layer of silica (SiO2). After the surface modification with an alkoxyamine derivative, polystyrene (PS) brushes of chain lengths ranging from 30,000 to 114,000 in Mn with relatively low polydispersities less than 1.5 in Mw/Mn were successfully grafted by surface-initiated nitroxide-mediated polymerization, where the Mn and Mw are the number- and weight-averaged molecular weights, respectively. The graft density reached a value as high as 0.9 chains nm−2. These core-shell hybrid particles (ZnS@SiO2-PS) were highly dispersible, without any aggregation, in various solvents good for PS, also forming a monolayer at the air-water interface by spreading its solution. The transmission electron microscopic observation of the monolayers deposited on a solid support revealed two-dimensionally close-packed arrays of particles. These monolayers exhibited a beautiful structural color dependent on the angle of incident light because of such an ordered array of the ZnS cores with a high refractive index. Hollow spheres constituted of a SiO2 shell with well-defined, high-density PS brushes were first synthesized by selective dissolution of the ZnS core from the ZnS@SiO2-PS hybrid particle. 相似文献
10.
Polymer modification of colloidal particles by spontaneous polymerization of surface active monomers 总被引:1,自引:0,他引:1
Adsorption and spontaneous polymerization of head- or tail-type surface active monomers having long methylene chains on colloidal
silica and δ-alumina were investigated. Both head-type and tail-type ammonium monomers on silica in chloroform or tetrahydrofuran
had the maximum adsorption on the respective adsorption isotherm. Above the monomer concentration giving the maximum adsorption,
it was observed that the monomer formed micelles or clusters in bulk solution with removal of adsorbed water molecules from
the silica surface. At the monomer concentration giving the maximum adsorption, heating the silica suspension containing the
monomer at 40°C or 60°C in tetrahydrofuran or chloroform solution resulted in spontaneous polymerization. The composite particles
formed by polymerization were observed to have many spots consisting of polymer on the surface. Therefore, it is suggested
that the monomers are concentrated by micelle-like aggregation on the silica surface and consecutively spontaneous polymerization
takes place. Adsorption of an anion-type monomer having a carboxyl group on δ-alumina, which exhibited a positive ζ potential
in neutral aqueous solution, was higher than that on colloidal silica, but did not spontaneously polymerize on alumina.
Received: 13 June 1998 Accepted in revised form: 19 August 1998 相似文献
11.
Facile fabrication of pH-sensitive core-shell nanoparticles based on HEC and PMAA via template polymerization 总被引:1,自引:0,他引:1
Youwei Zhang Qiaorong Jin Jiongxin Zhao Chengxun Wu Qingqing Fan Qimin Wu 《European Polymer Journal》2010,46(7):1425-24
Taking advantage of the specific hydrogen bonding interactions between the components, core-shell nanoparticles based on poly(methacrylic acid) (PMAA) and hydroxyethyl cellulose (HEC) can be efficiently prepared via facile one-step polymerization of MAA on HEC template in water. Various techniques were used to characterize in detail the sizes, morphology, and structures of the nanoparticles, as well as the interactions between the components. The core-shell structures of the nanoparticles were confirmed by TEM observation. Dynamic light scattering and fluorescence spectrometry were used to monitor the polymerization process, which indicates a size decrease and a hydrophobicity increase of the nanoparticles. A mechanism was proposed to explain the formation of core-shell nanoparticles during the template polymerization. The obtained nanoparticles are stable against urea, salt, temperature and in the storage; meanwhile, they exhibit pH-response: the volume of the nanoparticles increased more than six times as pH value of the medium increased from 2.8 to 3.7. 相似文献
12.
Synthesis of ZnO/polystyrene composites particles by Pickering emulsion polymerization 总被引:2,自引:0,他引:2
ZnO/polystyrene composite particles were synthesized by Pickering emulsion polymerization. ZnO nanoparticles were first prepared by reaction of zinc acetate and sodium hydroxide in ethanol medium. Then different amount of styrene monomer was emulsified in water in the presence of ZnO nanoparticles either by mechanical stirring or by sonication, followed by polymerization of styrene. Two kinds of initiators were used to start the polymerization, azobisisobutyronitrile (AIBN) and potassium persulfate (KPS). The X-ray diffraction pattern verified the crystal structure of ZnO and FT-IR spectra evidenced the existence of ZnO and polystyrene (PS) in ZnO/polystyrene composite particles. Different morphologies were observed for the composite particles when using different initiators. From TEM photographs, AIBN-initiated system produced mainly core-shell composite particles with PS as core and ZnO as shell, while KPS-initiated system showed both composite particles and pure PS particles. Two schemes of reaction mechanism were proposed to explain the morphologies accordingly. Both systems of composite particles showed good pH adjusting ability. 相似文献
13.
Min Jiang Zhaohui Zheng Xiaobin Ding Xu Cheng Yuxing Peng 《Colloid and polymer science》2007,285(9):1049-1054
Novel fluorinated polyurethane hybrid latexes in the size range of 40–50 nm, fluoroalkyl acrylate as fluorinated monomers,
with various fluorine content (F% = 9∼26 wt%) were successfully prepared via emulsion polymerization process without traditional emulsifier. The waterborne
polyurethane, which was synthesized by using isophronediisocyanate, dimethylol propionic acid, polyethylene glycols, etc.,
served not only as copolymerizable macromonomer but also as polymeric high molecular weight emulsifier. The structures of
polyurethane macromonomer and fluorinated polyurethane were characterized by Fourier transform infrared and H1-NMR. Particle size, zeta potential, micromorphology of the latex par.ticles, and surface properties were investigated by
dynamic light scattering, potential particle size analyzer, transmission electron microscopy, and contact angle measurement,
respectively. Results illustrated that the advantage of this process is that the size of fluorinated polyurethane hybrid particle
is less sensitive to the composition. Furthermore, it was showed that fluorinated polyurethane latex particles had core-shell
structures, especially when the content of fluorine was 26.08 wt%. Moreover, there was an obvious migration of fluorinated
groups to the surface during the formation of fluorinated polymer films, although fluorinated groups were covered by polyurethane
in latex particles. 相似文献
14.
利用硅烷偶联剂引发法制备核壳结构金属铝纳米粒子(Al NPs)@聚合物, 并研究了聚合反应时间和单体浓度对核壳结构尺寸的影响. 首先合成了硅烷偶联引发剂{2-溴-2-甲基-[3-(三甲氧基硅基)丙基]丙酰胺}, 并通过在甲苯中回流的方法, 将其锚定在金属铝纳米粒子表面. 然后, 在粒子表面引发甲基丙烯酸甲酯的原子转移自由基聚合, 形成聚甲基丙烯酸甲酯(PMMA)壳层. 通过核磁共振波谱仪(NMR)和傅里叶变换红外光谱仪 (FTIR)证明了引发剂和PMMA的成功接枝. 透射电子显微镜(TEM)图像表明, PMMA改性后的金属铝纳米粒子的尺寸和形貌基本不变, 且被厚度约为15 nm聚合物壳层完整均匀地包覆. 此外, 利用动态光散射(DLS)进一步揭示了聚合时间和单体浓度对核壳结构水合直径(Dh)的影响, 发现延长聚合时间或增加单体浓度均可显著提高核壳结构尺寸. 相似文献
15.
The in situ radical transfer addition polymerization of styrene from silica nanoparticles was carried out by the free radical polymerized of styrene in the presence of mercaptopropyl-modified silica nanoparticles as chain-transfer agent. The effects of the amount of the initiator, polymerizing temperature and polymerizing time on the convention of styrene (C) and the percentage of grafting were investigated. Results of elemental analysis, IR, X-ray photoelectron spectrometer and transmission electron microscope demonstrated that the desired polymer chains have been covalently bonded to the surface of the silica nanoparticles. A C of 42.56% and a PG of 38.10% could be achieved with the optimal condition. The polystyrene grafted silica nanoparticles could be separated and used as nanofiller for polymers. 相似文献
16.
以氯金酸为前驱体,十二烷基硫醇和硼氢化钠分别作为稳定剂和还原剂,采用相转移法制备了单分散的金纳米粒子.将金纳米粒子通过乳液聚合的方法制备了纳米金/聚苯乙烯复合粒子.通过紫外-可见吸收光谱(UV-Vis)研究了纳米金和纳米金/聚苯乙烯复合粒子的光吸收特性,使用傅立叶变换红外光谱(FT-IR)、X射线衍射(XRD)、透射电子显微镜(TEM)和动态光散射(DLS)对产物的组成、晶体结构、形貌、以及粒径进行了表征.结果表明,复合粒子为粒径分布较窄的球形,其中的金纳米粒子为面心立方结构.热失重分析(TGA)说明制备的纳米金/聚苯乙烯复合粒子具有很好的热稳定性. 相似文献
17.
Periyayya Uthirakumar 《European Polymer Journal》2004,40(11):2437-2444
Polystyrene/montmorillonite (PS/MMT) nanocomposites were prepared by in situ free radical intercalative polymerization, using 1, 3 and 5 wt% of a new cationic radical initiator-MMT hybrid. The corresponding nanocomposites were designated as PS/MMT-1, PS/MMT-3 and PS/MMT-5, respectively. The silicate layers were well exfoliated and randomly dispersed in the PS/MMT-1 and PS/MMT-3, but were less exfoliated in the PS/MMT-5, due to the predominant extra-gallery polymerization over the intra-gallery polymerization. The unique properties of nanocomposites resulted from the strong interactions between the nano-sized silicate layer surfaces and the polymer chains. The onset temperature of thermal degradation, and the glass transition temperature, increased with increasing hybrid content, up to 3 wt%. The molecular weights of the PS in the PS/MMT-1 and PS/MMT-3 were less than those calculated theoretically, due to the predominant intra-gallery polymerization. 相似文献
18.
A series of poly(butyl acrylate-co-methyl methacrylate)/poly (ethyl acrylate-co-acrylic acid) interpenetrating polymer network (IPN) was synthesized in latex form by emulsion polymerization. The multiphase morphology of the latex particles was studied after two-stage polymerization by using transimission electron microscope (TEM), the result indicated that the morphology of the particles comprises gradient shell structure, cellular structure and core-shell structure. The change of morphology might stem from emulsion polymerization by radiation initiation or chemical initiation and the weight composition of poly(EA-co-MMA) seed latex which formed the core. By radiation techniques, we successfully synthesized poly( BA-co-MMA)/poly(EA-co-AA) latex of core-shell structure having (42-8)/(46-4) weight compositions. The PA core-shell structure latex applied to textile as a water proofing coating showed higher water-pressure and easier handling than that with PA homogeneous phase structure latex. 相似文献
19.
Yi-Wen Chung Ing-Chi Leu Jian-Hong Lee Min-Hsiung Hon 《Colloids and surfaces. A, Physicochemical and engineering aspects》2006,290(1-3):256-262
High-quality polystyrene (PS) colloidal photonic crystals in large area were fabricated in 24 h via a capillary-enhanced process. Then, the photonic crystals with core-shell structure were obtained by incorporating silica nanoparticles into the interstitial space of opal template via a dipping process. The filling ratio (Vsilica) of interstitial space could be manipulated by dipping colloidal crystals into suspensions with different concentrations of silica nanoparticles, which in turn renders the obtained core-shell photonic crystals. The absorptive peak of opal without dipping process is at 445 nm as measured by UV–vis spectrometry. The filling ratios of 0.130, 0.167 and 0.253 can be calculated according to the modified Bragg's Law, which corresponds to the absorptive peaks for core-shell opals at 453, 463 and 469 nm obtained from suspensions with silica nanoparticles of 0.017, 0.122, and 0.244 wt%, respectively. Therefore, by using this dipping process, the characteristic absorption wavelength for photonic crystal will be varied easily, efficiently and cost effectively than that by traditional methods for constructing opal from monodispersed colloids of different diameters. 相似文献
20.
Guang Huang Zhichao Xiong Hongqiang Qin Jun Zhu Zhen Sun Yi Zhang Xiaojun Peng Junjie ou Hanfa Zou 《Analytica chimica acta》2014
Zwitterionic hydrophilic interaction chromatography (ZIC-HILIC) materials have been increasingly attractive in glycopeptide enrichment. However, the traditional ZIC-HILIC materials are modified with monolayer zwitterionic molecules on the surface, therefore, the hydrophilicity, detection sensitivity and loading capacity are limited. In this work, we synthesized novel silica nanoparticles with uniform poly(2-(methacryloyloxy)ethyl)dimethyl-(3-sul-fopropyl)ammonium hydroxide (PMSA) brushes grafted onto the surface via reversible addition-fragmentation chain transfer (RAFT) polymerization (denoted as SiO2-RAFT@PMSA). The resulting SiO2-RAFT@PMSA nanoparticles demonstrated low detection limit (10 fmol) and high recovery yield (over 88%) for glycopeptide enrichment from tryptic digest of human IgG. The SiO2-RAFT@PMSA nanoparticles were further applied for the analysis of mouse liver glycoproteome, a total number of 303 unique N-glycosylation sites corresponding to 185 glycoproteins was reliably profiled in three replicate nano-LC–MS/MS runs. Significantly, more glycopeptides were identified than those of nanoparticles, monolayer MSA molecules modified SiO2@single-MSA and nonuniform multi-layer PMSA brushes coated SiO2@PMSA, as well as commercial ZIC@HILIC beads and Click Maltose beads. The excellent performance of SiO2-RAFT@PMSA nanoparticles results from the non-fouling property, a large quantity of functional molecules and suitable link arms provided by uniform PMSA brushes, as well as efficient interaction between glycopeptides and uniform PMSA brushes. It is concluded that the synthesized SiO2-RAFT@PMSA nanoparticles exhibit great potential in glycoproteome analysis. Moreover, this strategy to modify nanopaticles with uniform polymer brushes via RAFT polymerization can also be explored to design other types of materials for bioseparation application. 相似文献