石蜡聚苯乙烯微球的制备

通过悬浮聚合技术合成了石蜡聚苯乙烯微球，研究了合成过程中引发剂浓度及交联剂用量对微球粒径及其分布的影响。     

影响单分散聚苯乙烯微球粒径因素的研究

利用正交实验设计的数学方法进行设计，考察不同因素对微球粒径的影响，以制备出不同粒径的聚苯乙烯微球，主要考察的因素有：温度，引发剂浓度，单体浓度以及离子浓度，同时对其交互作用进行了研究，结果表明，4种因素对粒径影响的排序为：温度，引发剂浓度，离子浓度，单体浓度，其中引发剂浓度与单体浓度的交互作用明显。     

浅谈稳定剂对MMA/MA分散共聚合的影响

以乙醇/水混合溶剂为分散介质,偶氮二异丁腈、聚乙烯吡咯烷酮和双甲基丙烯酸乙二醇酯分别为引发剂、稳定剂和交联剂进行了甲基丙烯烯酸甲酯/丙烯酸（MMA/AA）的分散共聚合研究。用透射电子显微镜和离心式粒径分布仪测定了粒子大小和粒度分布,重点讨论了稳定剂浓度对聚合速率,共聚物微球粒径及粒径分布的影响。发现随着稳定剂浓度的增加聚合速率增加,转化率提高,微球的粒径变小而分散性变好。     

用作颜填料的单分散聚合物微球的研制

以二乙烯基苯（DVB）为单体,偶氮二异丁腈（AIBN）为引发剂,乙腈为溶剂,用沉淀聚合法合成了高交联度的聚合物微球。讨论了反应时间、反应温度、转动速率、单体浓度以及引发剂浓度对聚合物微球粒径及粒径分布的影响,并用扫描电子显微镜（SEM）进行了表征。     

微波辐射无皂乳液聚合法制备PS微球

采用无皂乳液聚合法制备聚苯乙烯（PS）微球，以微波辐射加热方式代替传统油浴或水浴加热方式，研究了聚合体系中引发剂过硫酸钾的浓度、交联剂二乙烯苯与稳定剂α-甲基丙烯酸的体积比、微波功率大小对PS微球形貌、粒径及其分布的影响。结果表明，较传统加热方式，微波辐射加热方式极大地改善了PS微球的球形度和表面形貌。PS微球粒径随着引发剂浓度的增加呈现减小的趋势，随着交联剂与稳定剂体积比及微波功率的增加均呈现先减小后增大的趋势。当引发剂浓度为6.06×10^–3 mol/L、交联剂与稳定剂体积比为2∶1、微波辐射功率为300 W时所制备的PS微球表面光滑、球形度高、粒径分布均匀，平均粒径约为240 nm。PS微球表面带负电荷且分散性良好，并通过Hertz接触理论计算得到PS微球的压缩弹性模量约为2.75 GPa。     

正交试验法研究聚苯乙烯微球分散聚合法的制备

以苯乙烯为反应单体,聚乙烯吡咯烷酮为稳定剂,偶氮二异丁腈为引发剂,乙醇与水为反应介质,采用分散聚合法制备聚苯乙烯微球。实验中选取了PVP浓度、初始单体St浓度、引发剂浓度、分散介质的组成以及反应时间五个因素,每个因素选取了5个水平,设计5因素5水平正交试验表研究各因素对微球粒径变化及对微球单分散性的影响。实验结果表明,对于微球的分散性,各因素影响的大小为TimeStE/WPVPAIBN。对于微球的粒径,各因素影响的大小为E/WPVPTimeStAIBN。同时,成功制备出了平均粒径为0.851,1.133,1.257,1.366,1.747μm,单分散性好的聚苯乙烯微球。     

稳定剂对MMA/MA分散共聚合的影响

以乙醇 /水混合溶剂为分散介质 ,偶氮二异丁腈、聚乙烯吡咯烷酮和双甲基丙烯酸乙二醇酯分别为引发剂、稳定剂和交联剂进行了甲基丙烯烯酸甲酯 /丙烯酸 (MMA/AA)的分散共聚合研究。用透射电子显微镜和离心式粒径分布仪测定了粒子大小和粒度分布 ,重点讨论了稳定剂浓度对聚合速率 ,共聚物微球粒径及粒径分布的影响。发现随着稳定剂浓度的增加聚合速率增加 ,转化率提高 ,微球的粒径变小而分散性变好。提出了该体系分散聚合的接枝稳定机理。     

甲基丙烯酸与淀粉接枝共聚反应研究

用反相悬浮聚合法制备了可溶性淀粉与甲基丙烯酸接枝共聚物。研究了接枝效率、接枝转化率、微球收率与引发剂浓度、单体浓度、反应温度和反应时间的关系，用红外光谱（FT－IR）表征了接枝共聚物，结果表明：引发剂浓度为0．008mol/L，甲基丙烯酸与淀粉质量比为2．5：1，反应温度为50℃，反应时间2h，接枝效率最高，为96％，接枝转化率为39％，微球收率为47％。     

光引发RAFT分散聚合制备单分散聚合物微球

使用聚乙二醇基的大分子可逆加成断裂链转移(RAFT)试剂，在乙醇/水介质中通过光引发RAFT分散聚合制备聚甲基丙烯酸甲酯(PMMA)微球。通过扫描电子显微镜(SEM)对聚合物微球的形成进行探究，并研究了实验中各反应条件对聚合物微球粒径以及粒径分布的影响。结果表明：光引发剂的浓度对聚合物微球的粒径和粒径分布影响都不大；大分子RAFT试剂的添加量在6wt%～14wt%范围内都能形成单分散的聚合物微球；随着单体浓度的增加聚合物微球的粒径相应增大。     

聚甲基丙烯酸酯高分子微球的研究

通过分散聚合法制各了微米级单分散聚甲基丙烯酸甲酯微球.考察了不同聚合单体浓度、引发剂、稳定剂浓度和分散介质等因素对聚合体系的稳定性、微球粒径及分布的影响.通过研究发现,粒径随着聚合温度、引发剂浓度、单体用量的增加而增加;而随着稳定剂(PVP)的浓度的增大而减小.     

Uniform Polystyrene Particles by Dispersion Polymerization in Different Dispersion Medium

Using PVP K-30 as steric stabilizer and AIBN as initiator, uniform polystyrene (PS) particles were prepared by dispersion polymerization of styrene in ethanol/water and isopropanol/ water media. The effects of initiator and stabilizer concentration, alcohol/water volume ratio on the average sizes and size range of PS particles were investigated. Unifrom PS particles in the size range of 0.7-1.7 μm were obtained. The results showed that higher stabilizer concentration led to PS particles with smaller average sizes, and higher initiator concentration caused greater average particle sizes. It was also found that the average sizes reduced and size ranges became narrow as the polarity (solubility parameter) of dispersion medium employed was increased.     

Formation of monodisperse polyacrylamide particles by dispersion polymerization: particle size and size distribution

Highly monodisperse polyacrylamide microparticles were directly prepared by dispersion polymerization in aqueous alcoholic media initiated by 2,2′‐azobisisobutyronitrile using poly(N‐vinylpyrrolidone) as a steric stabilizer. Monomer conversion was studied dilatometrically and polymer molecular weight was determined viscometrically. The hydrodynamic diameter of polymer particles and its distribution were measured with a dynamic laser light scattering spectrometer. The number of the nuclei produced in the early stage of the polymerization was found to be constant during the remainder of the polymerization. The influences of various polymerization parameters, such as initiator concentration, monomer concentration, stabilizer content, medium polarity, and polymerization temperature on the particle size and size distribution were systematically investigated. Copyright © 2003 Society of Chemical Industry     

甲基丙烯酸甲酯的乳液聚合

以甲基丙烯酸甲酯为主要原料,过硫酸铵为引发剂,OP-10和十二烷基苯磺酸钠(1∶1)为混合乳化剂,聚乙烯醇为分散剂,用乳液聚合的方法合成了聚甲基丙烯酸甲酯乳液.考察了产品的转化率、粒径、红外光谱、粘度及其热稳定性并进行了表征.与传统的聚合方法相比,该聚合方法具有乳液粒径小且分布均匀、聚合速度快、所获得的聚合物纯度较高以及合成的聚乳液可以直接应用等优点.     

颗粒单分散聚丙烯酰胺凝胶微球的制备

引　言聚丙烯酰胺凝胶具有亲水性强、不易受微生物腐蚀和酶解、理化性质稳定以及结构参数易控制等优点 ,在医学免疫、生物工程领域有广阔的应用前景 .迄今为止 ,国内外虽有不少关于这种凝胶合成及应用的文献报道[1],但其基质微球的制备及相关技术的研究却很少 .近年来 ,人们分别用分散聚合法[2 ,3]、二步溶胀法[4 ,5 ]等合成了不同种类、不同级别的单分散、大粒径聚合物微球 ,并已应用到了许多技术领域 ,但对这些合成技术的规律性研究尚处在初始阶段 .本文在大量实验研究和理论分析的基础上 ,以乙基纤维素为悬浮剂、过硫酸铵为引发剂、苯为…     

微米级单分散聚苯乙烯微球的制备

以苯乙烯(St)为单体、偶氮二异丁腈(AIBN)为引发剂、聚乙烯吡咯烷酮(PVP)为分散稳定剂,在乙醇-水反应介质中,采用分散聚合法制备了微米级单分散聚苯乙烯(PS)微球。分别用电镜扫描和激光粒度仪表征了PS微球表面形貌、粒径及粒度分布,探讨了影响PS微球粒径及粒度分布的诸多因素。结果表明,AIBN用量(以单体质量计,下同)大于5.0%或PVP用量(以单体质量计,下同)小于2%时,PS粒子间有聚并现象;当St浓度为10%、AIBN用量为2.5%、PVP用量为5.5%、醇水质量比为90∶10、聚合温度为70℃时,制备的PS微球粒径为1.612μm、粒度分散系数为0.357,微球单分散性及球形度最佳。     

Monodisperse poly(p-chloromethylstyrene) microbeads by dispersion polymerization

In this study, an alternative dispersion polymerization method for the para isomer of chloromethylstyrene was proposed. Highly monodisperse poly(p-chloro-methylstyrene) (PCMS) particles in the size range of 1.67–3.75 μm were obtained. The monodispersity and the isolation yield of PCMS particles were significantly improved relative to the methods available in the literature. Azobisisobutyronitrile and polyacrylic acid were selected as the initiator and the steric stabilizer, respectively, in the dispersion medium composed of ethanol and methoxyethanol. The results indicated that the particle size increased with increasing initiator concentration. An increase in the stabilizer concentration led to a decrease in the particle size. The methoxyethanol/ethanol ratio was found as one of the most important parameters controlling the average size and the size distribution. Contrary to the tendencies noted in the literature, the particle size decreased with increasing polymerization temperature.     

均匀设计的甲基丙烯酸甲酯分散聚合反应研究

基于均匀设计方法对甲基丙烯酸甲酯（MMA）的分散聚合反应进行了试验设计，并通过回归分析，建立了聚甲基丙烯酸甲酯（PMMA）粒子相关性能参数（PMMA相对分子质量、粒径大小及分布）和各变量（单体质量分数、稳定剂用量、引发剂用量和反应介质溶度参数）之间的回归方程。根据回归方程进行了分散聚合反应的配方优化，得到了约束条件下的MMA分散聚合反应配方，实测值与预测值比较结果表明，回归方程的预测值与优化配方制备的PMMA粒子的各项性能实测值之间的相对偏差在10％以内，对试验配方设计有指导作用。     

Production of polymethylmethacrylate particles by dispersion polymerization in aqueous media with ceric ammonium nitrate

Polymethylmethacrylate particles with narrow size distributions with different sizes in the range of 1.25–4.58 μm were produced by dispersion polymerization of methylmethacrylate (MMA) in ethanol/water media, by using 2,2′-azobisisobutyronitrile (AIBN) (as an initiator), (PVP) poly(vinyl pyrrolidone) (as a stabilizer), and ceric ammonium nitrate (CAN) (as a coinitiator and also as a costabilizer). Particle size was increased by increasing the initiator concentration and the ethanol: water ratio, and by decreasing the monomer: dispersion medium ratio and the PVP and CAN concentrations. The addition of CAN in the recipe of the MMA polymerization improved the monodispersity, and also increased the monomer conversion rate. © 1996 John Wiley & Sons, Inc.     

Polymerization of vinyl pivalate in supercritical carbon dioxide and the saponification for the preparation of syndiotacticity-rich poly(vinyl alcohol)

This paper reports a successful free-radical dispersion polymerization of vinyl pivalate in supercritical carbon dioxide using poly(1H,1H-dihydroperfluorooctyl acrylate) and dimethylsiloxane-g-pyrrolidone carboxylic acid (Monasil PCA) as stabilizers. In both cases, no spherical polymer particles were obtained, which might be due to the high solubility of poly(vinyl pivalate) (PVPi) in supercritical carbon dioxide. The effects of the reaction time, pressure, temperature, monomer loading, stabilizer concentration and initiator concentration on the polymer yield and molecular weight of PVPi were also investigated. In addition, the formation of poly(vinyl alcohol) via saponification of the resulting PVPi is described.     

Drop coalescence processes in suspension polymerization of vinyl chloride

A tracer dye technique was used to investigate the effect of turbulence intensity, stirring time, and the type and concentration of the suspending agent, partially hydrolyzed poly(vinyl acetate) (PVA), on the coalescence rate of vinyl chloride monomer (VCM) droplets in an agitated liquid–liquid dispersion. It was found that the extent of coalescence rises slowly with mixing time, is roughly proportional to the agitation speed, and decreases sharply when the concentration of stabilizer is increased. Coalescence rate depended on the degree of hydrolysis of the stabilizer. The method of addition of initiator during VC suspension polymerization was also studied and its effects on the polymerization conversion and final PVC particles' properties were determined. It was found that the polymerization reaction occurs more uniformly in all the VCM droplets when the initiator was predissolved in the VCM prior to reaction compared with the case when the initiator was predispersed in the continuous water phase. Also, for the same reaction time, the conversion was higher in the former case. During polymerization, the concentration of PVA in the aqueous phase decreased substantially and the porosity of the polymer particles was reduced. © 1996 John Wiley & Sons, Inc.