交联聚苯乙烯单分散微球的制备

微米级粒度均匀的聚合物微球作为功能高分子材料在分析化学、生物化学、标准计量以及某些高新技术领域中应用广泛。制备聚合物微球的传统方法有乳液和悬浮聚合法。乳液聚合只能制备粒径为0．1-0．7μm的颗粒，采用无皂或低皂乳液聚合法制成的单分散聚合物微球粒径接近1μm，但难于达到1μm以上，且后处理比较麻烦；悬浮聚合制备的聚合物微球粒径则一般在100-1000μm之间，且是多分散性的。而分散聚合获得的微球呈单分散性，是制备粒径为1-10μm的单分散聚合物微球的有效方法。     

窄分布聚合物微球的制备及其在氨基酸分析上的应用

采用PVA和DBS-Na复合分散剂,在高速搅拌下(1500～2000转/min),用悬浮聚合法合成了粒度分布较窄的聚合物微球(3～10μm),并考查了聚合反应条件对聚合微球粒度及其分布的影响。最后,对所得磺化微球在氨基酸分析方面的应用进行了试验。     

粒径可控的聚乙烯醇交联微球VA/DVB的制备

以醋酸乙烯酯(VAc)为主单体,二乙烯基苯(DVB)为交联剂,聚乙烯醇(PVA)为分散剂,采用悬浮聚合法制备了交联微球VAe/DVB.重点考察了分散剂用量、搅拌速率、油水两相比例、NaCl用量等因素对交联微球的形成及其粒度的影响.使用甲醇对微球VAc/DVB进行醇解反应,制得了聚乙烯醇交联微球VA/DVB.结果表明:交联微球VA/DVB的物理形态决定于前驱体微球VAc/DVB的形貌与粒径.在悬浮聚合体系中,分散剂用量、搅拌速率与油水两相比是影响交联微球制备的主要因素,当分散剂用量太少(<0.3%)、搅拌速率太慢(<200 r/min)与油水两相体积比太大(>l:4)时,共聚合体系中均不能发生成球过程.控制悬浮聚合的反应条件,可以制备出球形度好、粒径可调控的交联微球VA/DVB.影响醇解反应的主要因素是反应温度,适宜的温度是40℃,反应15 h醇解度可达92%.     

有机颜料酞菁蓝微胶囊的原位微悬浮法制备及其表征

通过简单的超声分散及强力剪切将滤饼中的有机颜料颗粒以初级粒子形式均匀稳定地分散到单体分散液和微悬浮液中的单体小液滴内,经有机颜料单体分散液的预聚处理和原位微悬浮聚合制备得到一系列具有高颜料包裹率和窄粒径分布特点的微米级聚合物胶粒.实验观察和粒径分析DLS证明,预聚处理可明显提高微悬浮体系中单体液滴相的黏度,因而可有效改...     

种子溶胀悬浮聚合法制备分子印迹聚合物微球

 以酪氨酸为印迹分子 ,甲基丙烯酸为功能单体 ,三羟甲基丙烷三甲基丙烯酸酯 (TRIM )为交联剂 ,采用种子溶胀悬浮聚合法在水溶液中制备了一系列分子印迹聚合物微球 (MIPMs)。利用扫描电镜 (SEM)对此微球的粒径大小、粒径分布、表面孔与孔径分布等进行了分析研究 ,探讨了影响其形貌的主要因素 ,并将所得微球用作固定相研究了其分子选择吸附性能。研究表明 ,种子溶胀悬浮聚合法能够制得单分散性较好的、表面带有微孔的分子印迹聚合物微球 ,且该微球呈现出较好的特异吸附性能。     

N-乙烯基咪唑共聚交联微球的制备及其对二氯苯酚的吸附特性

采用悬浮聚合法,以N-乙烯基咪唑(NVI)为主单体、苯乙烯(St)为共单体、乙二醇二甲基丙烯酸酯(EGDMA)为交联剂、聚乙烯醇(PVA)为分散剂,制备了吸附材料PNVI-St交联微球。重点考察了分散剂用量、搅拌速率、油水两相体积比、交联剂用量、NaCl用量对交联微球的成球性能及粒度的影响规律,研究了该微球对二氯苯酚的静态吸附性能。结果表明:分散剂用量、搅拌速率与油水两相体积比是影响交联微球制备的主要因素,在水相中加入电解质NaCl有助于成球过程,控制悬浮聚合的反应条件,可以制备出球形度好、粒径在100~200μm可调控的交联微球PNVI-St。静态吸附实验结果表明:凭借强烈的氢键相互作用,微球表面的咪唑基团对二氯苯酚具有很强的吸附能力,饱和吸附量可达143 mg/g。     

壳聚糖大分子链的形态调控及其在微悬浮聚合中的分散稳定作用

以易去除可回用的壳聚糖(CS)为分散剂,通过微悬浮聚合制备微米级的软硬质聚合物胶粒.考察不同酸碱度下水相介质中CS大分子链的质子化程度、亲疏水性和形态结构,及其对油水界面处CS存在形态的影响,进而评估其对剪切均质化所制单体液滴的分散稳定作用.发现通过调节体系pH值可较容易地控制CS大分子链的质子化程度、亲疏水性以及在单体液滴表面的吸附效率和铺展程度,进而可在弱酸性环境下调控微悬浮聚合体系中CS的分散能力和稳定效果.特别是当pH值在6.0左右时,CS大分子链质子化程度和亲疏水性适中,链内易形成具有一定内聚密度的高分子链收缩构象、链间易形成由多根CS链缠结而成的疏松聚集状态.在此状态下的CS链对苯丙单体液滴具有较强的分散能力和稳定作用,因而通过微悬浮聚合可制得形态结构规整、分散状态良好的聚合物粒子.进一步与微悬浮聚合常用的无机粉末类和高分子类分散剂进行应用效果比较,发现CS具有形态调控性好、分散稳定效率高、易去除能回用、特别适合制备软质微米胶粒等优点,是一种有别于无机粉末类和高分子类分散剂的新型微悬浮聚合分散剂.     

红霉素分子印迹聚合物微球的制备及性能研究

以红霉素为模板分子,甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,在水相中采用悬浮聚合法制备了红霉素分子印迹聚合物微球。利用扫描电镜对其表面形貌进行了表征,探讨了不同分散剂浓度、水油比、搅拌速度等参数对聚合物微球粒径及粒径分布的影响,重点对聚合工艺进行了优化,并将所得的聚合物用作吸附剂研究了其分子识别与选择性能。研究表明,该方法合成的聚合物微球平均粒径为40~130μm,对模板分子具有较高吸附性能和选择性识别能力,其分离因子达1.83,而动态吸附饱和吸附量则达到了42.59μmol/g。     

分散聚合制备粒度均匀的聚甲基丙烯酸环氧丙酯微球

文中描述了粒度均匀的聚甲基丙烯酸环氧丙酯微球的制备,所采用的是分散聚合方法,系统地研究了溶剂体系、单体浓度、引发剂类型与浓度、稳定剂用量、反应温度等各种聚合参数,对聚合产物粒度及其分散性的影响．在优化反应条件的基础上,制备出了微米级（１～８μｍ）粒度均匀性基本呈现单分散的聚合物微球．     

甲醛分子印迹聚合物微球的制备及其在针式萃取-气相色谱联用技术中的应用

本研究选用甲醛为印迹分子,4-乙烯基吡啶为功能单体,乙二醇二甲基丙烯酸酯为交联剂,采用矿物油包被悬浮聚合法制备高选择性识别的分子印迹聚合物.与本体聚合法相比,此法很好地保护了聚合物的印迹位点,得到的微球形状规则.利用制备的聚合物微球作为吸附剂填充针式萃取装置,并与气相色谱联用分析了气体中的痕量甲醛.实验考察了一系列聚合...     

Covalent Assembly of Hierarchical Particles by Efficient Coupling of β‐Diketones and Benzyl Chloride

A coupling reaction is performed between polymeric nanoparticles and microparticles via the nucleophilic substitution of pendent β‐diketone groups with benzyl chloride. The coupling reaction results in the formation of hierarchical particles, through the nanoparticles being covalently linked onto the microparticles. The coupling reaction is tracked by TEM and SEM, and the formation of covalent C–C bonds through the coupling reaction between the polymeric nanoparticles and microparticles is confirmed by solid‐state ¹³C CP‐MAS NMR spectroscopy and XPS. The proposed coupling reaction between the nanoparticles and the microparticles is believed to be a promising strategy in particle‐surface modification.     

新型微球载体材料——PACA-co-PEG的性能

聚氰基丙烯酸烷基酯;药物载体;生物降解性     

One-pot synthesis of highly folded microparticles by suspension polymerization

A facile method of preparing highly folded cross-linked polymeric microparticles has been developed via one-pot suspension polymerization under high-speed homogenization. The wrinkles result from the evaporation of solvent in the cross-linked microparticles. The effects of microparticle cross-linking density and solvent on the polymer have been studied in detail. It was found that a medium cross-linking density (DVB/St = 0.5 by weight) is optimal for producing the most folded surface and the higher the solvent content, the deeper the surface wrinkles. This method is very simple and in principle can be applied to produce wrinkled microparticles with other chemical compositions.     

A hierarchical model of crystallization in polymeric gels and porous solids

A kinetic model of the crystallization of substances in the volume of an agglomerate of many microparticles or in a polymeric gel in solution with a given composition and temperature was formulated. The model takes into account the diffusion of the crystallizing substance from outside into the space between microparticles in an agglomerate or between polymeric globules in a gel and then from this space into the volume of microparticles (globules) with the simultaneous nucleation and growth of microcrystals of the crystallizing substance. The possibility of simultaneous diffusion of several crystallizing substances, which chemically react with each other to produce product microcrystals, heating of the gel (solid) by the heat of crystallization, pushing the solution out from the space between microparticles, and changes in the volume of the gel (solid) as a result of crystallization is considered. The model was used to develop a classification of crystallization types in gels and porous solids and interpret several phenomena described in the literature. A hypothesis was advanced concerning some unknown phenomena related to crystallization.     

Fabrication of hierarchical microparticles by depositing the in situ synthesized surface nanoparticles on microspheres during the seed emulsion polymerization

A general strategy for the synthesis of polymeric hierarchical microparticles containing surface nanoparticles through modified seed emulsion polymerization is proposed. This modified seed emulsion polymerization has a character that suitable amount of monomer miniemulsion is added during the polymerization. The in situ synthesized surface nanoparticles which are resulted from the monomer miniemulsion as well as the shell-forming polymer coagulate on the seed particles and therefore hierarchical microparticles are fabricated. Various polymeric hierarchical microparticles containing 20-36 nm poly(styrene-co-acrylamide), poly(styrene-co-acrylic acid), and polystyrene surface nanoparticles are synthesized following the proposed method. The advantages in the present synthesis including both the well controls in the size, the composition, and the number of the surface nanoparticles and the convenience are demonstrated. The proposed strategy is anticipated to be a general method to fabricate hierarchical microparticles and is believed to have promising application in particle surface modification.     

Synthesis of nonspherical superparamagnetic particles: in situ coprecipitation of magnetic nanoparticles in microgels prepared by stop-flow lithography

We present the synthesis of nonspherical magnetic microparticles with multiple functionalities, shapes, and chemistries. Particle synthesis was performed in two steps: polymeric microparticles functionalized homogenously with carboxyl groups were generated using stop-flow lithography, and then in situ coprecipitation was used to grow magnetic nanoparticles at these carboxyl sites. With successive growth of magnetic nanoparticles, we obtained polymeric particles with saturation magnetizations of up to 42 emu/g microparticle. The growth in the magnetic nanoparticle mean size and polydispersity was determined from the magnetization curves obtained following each growth cycle; nanoparticle sizes were limited by the physical constraint of the effective mesh within the hosting gel microparticle. Particles with spatially segregated domains of varying magnetic properties (e.g., Janus particles, particles with step changes in magnetite concentration, etc.) can be synthesized readily using this approach.     

Fabrication of Porous Titania Particles from Water-in-Oil Emulsions for the Applications of Photocatalyst

In this study, polystyrene nanospheres were synthesized by dispersion polymerization using batch-type reactor for the self-organization with precursor materials inside emulsion droplets. Mechanical homogenization was applied for the emulsification of the polymeric nanospheres and titanium diisopropoxide bis (acetylacetonate) to produce the macroporous titania particles by evaporation-driven self-assembly. Similarly, spherical titania crystallites could be synthesized via self-organization using triblock copolymer instead of polymeric latex beads after successive calcination. The morphologies of the porous particles were observed using electron microscope, and the crystallinity of the porous titania particles was analyzed by powder x-ray diffraction. As a demonstrative application, the macroporous titania microparticles with anatase phase were adopted as photocatalyst for the decomposition of Rhodamine B, and excellent catalytic performance was observed with higher rate constant compared to the result from commercial titania nanocolloid. Collectively, our macroporous titania microparticles were found to be safe catalytic materials for human body minimizing the skin toxicity since the size of the catalysts is in the micron-range.     

Continuous fabrication of biocatalyst immobilized microparticles using photopolymerization and immiscible liquids in microfluidic systems

We report a novel technique for manufacturing polymeric microparticles containing biocatalysts by the behavior of immiscible liquids in microfluidic systems and in situ photopolymerization. The approach utilizes a UV-polymerizable hydrogel/enzyme solution and an immiscible oil solution. The oil and hydrogel solutions form emulsions in pressure-driven flow in microchannels at high values of the dimensionless capillary number (Ca). The resultant hydrogel droplets are then polymerized in situ via exposure to 365 nm UV light. This technique allows for the generation of monodisperse particles whose size can be controlled by the regulation of flow rates. In addition, both manufacturing microparticles and immobilizing biocatalysts can be performed simultaneously and continuously.     

Effect of preparation conditions on properties of polylactide and polystyrene and their composite microparticles made by emulsion solvent evaporation method

In this study, polylactide and polystyrene microparticles have been prepared by emulsion solvent evaporation method. Effects of polymer nature, stirring speed, emulsifier, and concentration of the components on the size, size distribution and morphology of polymeric microparticles have been investigated. 11-Acryloyl-aminoundecanoic acid and its polymer poly(11-acryloyl-aminoundecanoic acid) were tested for comparison with traditional emulsifiers such as sodium dodecylsulfate. Interfacial tension measurement was applied to compare these emulsifiers. Dynamic light scattering and scanning electron microscopy were used to analyze microparticles. Polylactide/polystyrene composite microparticles have been prepared as well; their surface morphology has been studied.