蒸馏沉淀聚合法制备窄分散聚二乙烯基苯-co-丙烯腈功能聚合物微球

采用蒸馏沉淀聚合法,利用过氧化苯甲酰(BPO)为引发剂,在不加任何稳定剂和不搅拌的情况下,丙烯腈(AN)和二乙烯基苯(DVB)为共聚单体制备了不同交联度的微米和亚微米窄分散聚合物微球,考查了共聚单体对球体的影响,并用扫描电镜(SEM)和红外光谱对微球进行了表征.     

Reparation of silica/poly(methacrylic acid)/poly(divinylbenzene-co-methacrylic acid) tri-layer microspheres and the corresponding hollow polymer microspheres with movable silica core

 Hollow poly(divinylbenzene-co-methacrylic acid) (P(DVB-co-MAA)) microspheres were prepared by the selective dissolution of the non-crosslinked poly(methacrylic acid) (PMAA) mid-layer in ethanol from the corresponding silica/PMAA/P(DVB-co-MAA) tri-layer hybrid microspheres, which were afforded by a three-stage reaction. Silica/PMAA core-shell hybrid microspheres were prepared by the second-stage distillation polymerization of methacrylic acid (MAA) via the capture of the oligomers and monomers with the aid of the vinyl groups on the surface of 3-(methacryloxy)propyl trimethoxysilane (MPS)-modified silica core, which was prepared by the Stöber hydrolysis as the first stage reaction. The tri-layer hybrid microspheres were synthesized by the third-stage distillation precipitation copolymerization of functional MAA monomer and divinylbenzene (DVB) crosslinker in presence of silica/PMAA particles as seeds, in which the efficient hydrogen-bonding interaction between the carboxylic acid groups played as a driving force for the construction of monodisperse hybrid microspheres with tri-layer structure. The morphology and the structure of silica core, silica/PMAA core-shell particles, the tri-layer hybrid microspheres and the corresponding hollow polymer microspheres with movable silica cores were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy (XPS).     

Preparation of polymer microspheres from solutions

Polymer microspheres are obtained by the dropwise addition of a precipitant, containing a polymeric stabilizer, into a polymer solution, containing a polymeric stabilizer. The polymer and stabilizer concentrations, the stirring speed, and the precipitation temperature determine the size and size uniformity of the microspheres. Seven polymer microspheres of polyimide, poly(ether imide), poly(ether ketone), poly(phenylene oxide), polysulfone, poly(vinylidene fluoride), and cellulose diacetate have been prepared with dimethylacetamide as the solvent, with water as the precipitant, and with poly(vinyl alcohol) as the stabilizer. The size and size uniformity of the obtained microspheres are d = 2.3–25.7 μm and ? = 0.15–0.50, respectively (? = σ/d, where ? is the dispersion coefficient, d is the average diameter, and σ is the standard deviation of the diameter). © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 159–165, 2003     

聚苯乙烯微球表面接枝丙烯腈的研究

采用分散聚合法制备出平均粒径为3.85 μm的窄分布聚苯乙烯微球， 并在此基础上引入第二单体丙烯腈进行共聚反应， 制备出平均粒径为4.02 μm的窄分布苯乙烯-丙烯腈共聚物微球. 对聚苯乙烯微球和苯乙烯-丙烯腈共聚物微球进行了形貌及粒径、红外光谱、差示扫描量热法(DSC)分析， 结果表明丙烯腈基团均匀分布在聚苯乙烯微球表面， 提高了聚苯乙烯微球表面的极性.     

Synthesis of monodisperse poly(divinylbenzene) microspheres

Highly crosslinked monodisperse poly(divinylbenzene) microspheres were produced by precipitation polymerization with acetonitrile as solvent. The radical initiators AIBN, BPO, and ADVN were used. The process does not require stabilizers of any type, and produces monodisperse particles with diameters between 2 and 5 μm, depending on the conditions. These microspheres do not swell or dissolve in any common solvent, and have clean, stabilizer-free surfaces. The particle formation and growth mechanism is proposed to resemble that of dispersion polymerization, except that the particles are stabilized against coagulation by their rigid, crosslinked surfaces rather than by added stabilizers. Spherical particles were formed only at effective crosslinker/monomer or divinyl/monovinyl ratios larger than 1 : 2. © 1993 John Wiley & Sons, Inc.     

两亲高分子微球的合成与表征

通过苯乙烯和聚氧乙烯大分子单体的共聚,合成了粒径在0.5μm～1.5μm的两亲高分子微球.随着聚氧乙烯大分子单体浓度的增加,微球粒径减小.通过扫描电镜,IR等分析手段对微球进行了表征.     

Effects of reaction temperature and reaction time on positive thermosensitivity of microspheres with poly(acrylamide)/poly(acrylic acid) IPN shells

We have successfully prepared monodispersed positively thermoresponsive core-shell hydrogel microspheres with poly(acrylamide-co-styrene) [P(AAM-co-St)] cores and IPN(interpenetrating polymer network)-based shells composed of poly(acrylamide)/poly(acrylic acid). The submicron-sized monodispersed P(AAM-co-St) core seeds were prepared by using a surfactant-free emulsion polymerization method, and the IPN-based shell layers were fabricated onto the core seeds by using a method of sequential IPN synthesis. Effects of reaction time and reaction temperature during preparation of IPN on the particle size, monodispersity, and thermoresponsive characteristics of microspheres were investigated. The results show that the sizes of particles with IPN shell layer are smaller than that of seeds, and the change of monodispersity among them is not obvious and the monodispersity of particles prepared under higher reaction temperature is higher than that of seeds and those particles prepared under lower reaction temperature. With increasing reaction time, thermoresponsive characteristics of microspheres increases. While thermoresponsive characteristics of microspheres decreases sharply with increasing reaction temperature. The results display preparation of IPN-structured microspheres is so careful to need longer reaction time and lower reaction temperature.     

微米级单分散共聚物微球的制备

用分散聚合法制备了苯乙烯 甲基丙烯酸甲酯微米级单分散共聚物微球 ,粒径为 5 4 μm .将分散聚合体系与乳液聚合体系进行了比较 ,并对共聚物微球的形貌、粒径分布及共聚情况进行了表征研究 .     

Preparation of styrene/acrylonitrile copolymer microspheres and their composites with metal particles

 Monodispersed poly(styrene-co-acrylonitrile) [P(St-co-AN)] microspheres were prepared by emulsifier-free emulsion copolymerization of St with AN. Fourier transform IR spectroscopy and elemental analysis were used to measure the content of AN in the poly(St-co-AN) microspheres. X-ray photoelectron spectroscopy (XPS) measurements indicated the presence of an AN unit on the surface of the microspheres. The combined results of the elemental analysis and the XPS measurements showed that the copolymer on the surface of the P(St-co-AN) particles was rich in AN compared with that in the interior of the particles. P(St-co-AN)–metal composite particles were prepared by chemical metal deposition. The addition of nickel could improve the distribution of cobalt on surface of the polymer microspheres. The preparation of polymer–bimetal composite particles was tried. Transmission electron microscopy and XRD were used to study the distribution and structure of the deposited metal particles. Received: 30 June 1999/Accepted in revised form: 16 September 1999     

Preparation of magnetic microspheres with thiol-containing polymer brushes and immobilization of gold nanoparticles in the brush layer

Narrow-disperse magnetic microspheres were prepared by alkaline coprecipitation of Fe²⁺ and Fe³⁺ ions within poly(acrylic acid–divinylbenzene) microspheres that were prepared by distillation–precipitation copolymerization. Magnetic microspheres with polymer brushes that contain epoxy groups were prepared by graft copolymerization of glycidyl methacrylate and glycerol monomethacrylate via atom transfer radical polymerization (ATRP) from the magnetic microsphere surfaces. Subsequently, magnetic microspheres with thiol-containing polymer brushes were prepared by treating the epoxy group-containing magnetic microspheres with sodium hydrosulfide. Gold nanoparticles were immobilized in the brush layer of the thiol-containing magnetic microspheres through Au–S coordination. The catalytic activity of the gold nanoparticle-immobilized magnetic microspheres was investigated using the reduction of 4-nitrophenol to 4-aminophenol with sodium borohydride as a model reaction. The catalyst could be reused for over 10 cycles without noticeable loss of catalytic activity.     

氨基两亲高分子磁性微球的制备与表征

采用分散聚合法,以乙醇水为介质,在Fe3O4磁流体存在下,通过苯乙烯与聚氧乙烯大分子单体(MPEO)共聚制备了同时具有两亲性和磁响应性的端基为氨基的高分子微球.改变聚合条件可以得到平均粒径范围在5～80μm,氨基含量为0.01～0.25mmolg的两亲磁性高分子微球.     

Adsorption of protein on the surface of thermosensitive poly(methyl methacrylate) microspheres modified with the N-(2-hydroxypropyl)methacrylamide and 2-(methacryloyloxy)ethyl phosphorylcholine moieties

A series of microspheres composed of methyl methacrylate (MMA) and N-(2-hydroxypropyl)methacrylamide (HPMA), and/or 2-(methacryloyloxy)ethyl phosphorylcholine (MPC), i.e., binary copolymer microspheres [poly(HPMA-co-MMA)_KPS and poly(HPMA-co-MMA)_ABIP] and ternary ones [poly(HPMA/MPC-co-MMA)_KPS and poly(HPMA/MPC-co-MMA)_ABIP], were prepared by emulsifier-free emulsion copolymerization using potassium peroxodisulfate (KPS) or 2,2′-azobis[2-(imidazolin-2-yl)propane] dihydrochloride (ABIP) as initiators. The decrease in ζ-potential of the polymer microspheres is caused by the addition of the HPMA and/or MPC moieties. Equilibrium water content of poly(HPMA-co-MMA)_ABIP showed a remarkable swelling change with a change in response to temperature: the hydrated conformation at 28°C and the dehydrated one at above 40°C. The adsorption of protein on the polymer microspheres also changed in response to change in temperature. The ternary polymer microspheres effectively suppressed the adsorption both of Alb and Glo, less than binary ones. A series of polymer microspheres are expected to apply as a novel drug carrier with both thermosensitive and nonthrombogenic functions. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3349–3357, 1997     

Porous monodisperse poly(divinylbenzene) microspheres by precipitation polymerization

The precipitation polymerization of commercial divinylbenzene in acetonitrile containing up to 40 vol. % toluene or other cosolvents is shown to produce novel porous monodisperse poly(divinylbenzene) microspheres. These microspheres have diameters between 4 and 7 μm, total pore volumes of up to 0.52 cm³/g, and surface areas of up to 800 m²/g. As no surfactant nor stabilizer was used in the preparation of these particles, their surfaces are free of any such residues. The particles were slurry-packed into stainless steel columns for size exclusion chromatography evaluation, and the results show an exclusion limit at molecular weights of 500 g/mol. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1543–1551, 1998     

Preparation of narrow or monodisperse poly(ethyleneglycol dimethacrylate) microspheres by distillation-precipitation polymerization

Highly crosslinked narrow or monodisperse poly(ethyleneglycol dimethacryltae) (polyEGDMA) microspheres were prepared by distillation-precipitation polymerization in neat acetonitrile with 2,2′-azobis(2-methyl propinitrile) (AIBN) as an initiator. The polymer microspheres with clean surfaces due to the absence of any added stabilizer in the reaction system were formed simultaneously through a precipitation manner during the distillation of acetonitrile off the reaction system. The effects of the solvent, initiator concentration, monomer concentration and comonomer (divinylbenzene, DVB) fraction on the formation of the microspheres were investigated. Narrow- or monodisperse particles with spherical shape and smooth surface were obtained with diameters between 1.18 and 2.50 μm with monomer loading lower than 3.13 vol%. The surfaces of the microspheres became rougher, some elliptic particles and doublet or triplet appeared with the increase of monomer concentration (as high as 3.75 vol%). The yield of polymer microspheres was increased from 31% to 75% with the increase of EGDMA fraction from 0 to 100% when EGDMA was copolymerized with DVB. The resulting polymer microspheres were characterized with scanning electron microscope (SEM) and Fourier transform-IR spectra.     

Synthesis of core‐shell poly(divinylbenzene) microspheres via reversible addition fragmentation chain transfer graft polymerization of styrene

Styrene has been grafted from crosslinked poly(divinylbenzene) core microspheres by both reversible addition fragmentation chain transfer (RAFT) polymerization and conventional free radical polymerization. The core microspheres were prepared by precipitation polymerization. Crosslinked poly(DVB) core microspheres containing double bonds on the particle surface can be used directly to graft polymers from the surface by RAFT without prior modification of the core microspheres. The RAFT agent 1‐phenylethyl dithiobenzoate (PEDB) was used: Particle sizes increased from 2 μm up to 3.06 μm, and the particle weight increased by up to 6.5%. PEDB controls the particle weight gain, the particle volume, and the molecular weight of the soluble polymer. PEDB was also used to synthesize core poly(DVB) RAFT microspheres that contain residual RAFT end groups on the surface and within the particle. Styrene was subsequently grafted from the surface of these core poly(DVB) RAFT microspheres. The generated microspheres were characterized by ¹H‐NMR spectroscopy, focused ion beam (FIB) milling, Coulter particle sizing, and size exclusion chromatography. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5067–5076, 2004     

磁性聚合物微球的制备及其热重曲线的特征分析

采用改进的种子乳液聚合法制得了微米尺度表面羧基功能化的超顺磁性复合微球.通过动态光散射粒度仪(DLS)、透射电子显微镜(TEM)、振动样品磁强计(VSM)对所制备的磁性功能聚合物微球的各项性能进行了表征.通过热失重分析(TGA)、热质联用分析(TGA-MS)、拉曼光谱(RS)、X射线光电子能谱(XPS)对磁性功能聚合物...     

Preparation of P(MBA‐co‐MAA)/Zr(OH)4/P(EGDMA‐co‐MAA)/TiO2 Tetra‐layer Hybrid Microspheres and the Corresponding ZrO2/TiO2 Double‐shelled Hollow Microspheres

Double‐shelled zirconia/titania (ZrO₂/TiO₂) hollow microspheres were prepared by the selective removal of the polymer components via the calcination of the corresponding tetra‐layer poly(N,N′‐methylenebisacryl amide‐co‐methacrylic acid) (P(MBA‐co‐MAA))/Zr(OH)₄/poly(ethyleneglycol dimethacrylate‐co‐methacrylic acid) (P(EGDMA‐co‐MAA))/TiO₂ hybrid microspheres. These tetra‐layer microspheres were synthesized by the combination of the distillation copolymerization of N,N(‐methylenebisacryl amide‐co‐methacrylic acid (MBA) or ethyleneglycol dimethacrylate (EGDMA) crosslinker and methacrylic acid (MAA) for the preparation of polymer core and third‐layer as well as the controlled sol‐gel hydrolysis of inorganic precursors for the construction of zirconium hydroxide (Zr(OH)₄) and titania (TiO₂) layers. The thicknesses of zirconia and titania shell‐layers were conveniently controlled via varying the feed of zirconium n‐butoxide (Zr(OBu)₄) and titanium tetrabutoxide (TBOT) during the sol‐gel hydrolysis, while the sizes of polymer layers were tuned through a multi‐stage distillation precipitation copolymerization. The structure and morphology of the resultant microspheres were characterized by transmission electron microscopy (TEM), X‐ray diffractometer (XRD), X‐ray photoelectronic spectroscopy (XPS), and thermogrametric analysis (TGA).     

锰-二茂铁基配位聚合物微球的制备与表征

采用溶剂热法制得了一系列锰-二茂铁基配位聚合物微球,系统研究了反应时间、反应物浓度等因素对配位聚合物微球的形貌和尺寸的影响规律,采用SEM、TEM、PXRD、EDX和FTIR等方法研究了微球的形貌、尺寸和结构等.发现通过调节反应时间,可使微球的尺寸约在4 ～9 μm范围内变化,提高反应物浓度可使微球从光滑的球形结构向核...     

Preparation and Characterization of Titania-grafted Poly（styrene-divinybenzene） Nanocomposite Microspheres

Titania-grafted poly（styrene-divinylbenzene）（TiO2/PSt-DVB） nanocomposite microspheres were prepared by an open-ring reaction and radical grafting copolymerization method. The TiO2 nanoparticles were first modified by attachment of epoxy groups to their surfaces to provide reactive groups that could covalently bond to the polymer （PSt-DVB） microspheres. The nanocomposite obtained was characterized by FTIR, SEM, XRD, and TGA analyses as well as UV-Vis spectrophotometry. The results indicated that the TiO2 nanoparticles were uniformly grafted onto the surface of the polymer microsphere producing grain sizes of about 5―10 μm. The modified TiO2 showed better UV absorbing property than the unmodified form, and the nanocomposite also retained the same UV absorbing property as the free modified TiO2 nanoparticle.     

MICRON CORE-SHELL PARTICLES PREPARED BY GRAFTING POLYMERIZATION OF METHYL METHACRYLATE FROM NARROW DISPERSE SURFACE OF CHLOROMETHYLATED POLYDIVINYLBENZENE VIA ATRP

Grafting of poly(methyl methacrylate) from narrow disperse polymer particles by surface-initiated atom transfer radical polymerization (ATRP) was investigated. Polydivinylbenzene (PDVB) particles were prepared by dispersion polymerization with poly(N-vinyl pyrrolidone) (PVP) as the stabilizer. Chloromethylated PDVB was used as initiating core sites for subsequent ATRP of methyl methacrylate with CuBr/bpy as catalyst system. It was found that poly(methyl methacrylate) was grafted not only from the particle surfaces but also from within a thin shell layer, leading to particles size increases from 2.38-3.00μm with a core-shell structure particles. The grafted core-shell particles were characterized with FTIR, SEM, DSC.