分散聚合法制备单分散交联聚苯乙烯微球

以苯乙烯为单体、二乙烯基苯为交联剂,通过优化反应条件,制备了平均粒径为3.28～9.04 μm的单分散聚苯乙烯微球和平均粒径为6.60 μm的单分散交联聚苯乙烯微球.探讨了单体浓度、引发剂含量、分散稳定剂用量对微球粒径和分散性的影响.热稳定性分析表明:交联聚苯乙烯微球耐热性明显优于线性聚苯乙烯.     

交联剂加入方式对聚苯乙烯微球形貌和分散性能的影响

以醇水混合液为分散介质,偶氮二异丁腈为引发剂,聚乙烯吡咯烷酮为稳定剂,二乙烯基苯为交联剂,采用分散聚合法一步制备了粒径约为1μm的单分散交联聚苯乙烯微球;采用扫描电镜和激光粒度仪等分析微球表面形貌及粒径分布,研究了滴加交联剂开始时间、交联剂浓度、引发剂浓度等对微球形貌和分散性能的影响.结果表明,在实验进行4h时加入交联剂,且交联剂滴加持续时间为2h的条件下,可制得平均粒径为1μm左右的交联聚苯乙烯微球,其具有较好的单分散性和球形度,且表面光滑.     

分散聚合法制备单分散聚苯乙烯微球

以苯乙烯为单体,偶氮二异丁腈为引发剂,聚乙烯吡咯烷酮为分散稳定剂,在乙醇/水的极性反应体系中,使用分散聚合法制备了聚苯乙烯(PS)微球。研究了制备工艺对微球分子量等远程结构参数的影响。研究结果表明:在适合微球形成的单体用量、引发剂和分散稳定剂的浓度、反应温度、时间和乙醇/水的比例等参数下,克服了以往存在的粒径不均匀、分子量较低、微球表面圆整光洁度较低和产率偏低等主要问题,制备了粒径在1.5~3μm之间、粒径分布1.05~1.08、分子量80×104左右、最高得率达97%、球体表面光洁、球形对称均匀且相互不粘连的单分散PS微球。     

单分散聚苯乙烯交联微球可控制备的研究进展

单分散聚苯乙烯交联微球是一类具有高比表面积、吸附性强以及高表面活性的材料,以其优异的疏水性、优越的热稳定性和耐溶剂性能在生物医学、标准计量、电子信息、分析化学、色谱分离等领域具有十分广阔的应用前景,近年来有关交联聚合物微球的制备以及机理研究成为一大热点并且发展较快。本文重点介绍了交联剂存在下分散聚合的反应机理,探讨了单体、引发剂、交联剂、分散剂以及分散介质等对单分散聚苯乙烯交联微球可控制备的影响,展望了聚苯乙烯交联微球的发展趋势和应用前景。     

单分散聚苯乙烯微球的制备及影响因素研究

以聚乙烯吡咯烷酮为分散剂，无水乙醇为反应介质，偶氮二异丁腈为引发剂，采用分散聚合工艺，通过优化反应条件，制备出了粒径为5μm单分散（分散系数≤5％）聚苯乙烯微球。所制备的聚苯乙烯微球标准偏差δ＝0．16μm，分散系数ε＝0．02，且具有良好的球形度，表面非常光滑，无破损，无缺损。对影响单分散聚苯乙烯微球的因素进行了研究，结果表明：随着分散稳定剂用量的增加，聚苯乙烯微球的粒径减小；随着单体和引发剂用量的增加，聚苯乙烯微球的粒径增大。分散稳定剂和单体用量是影响聚苯乙烯微球粒径分布的两个主要因素。     

反应原料组成对单分散苯乙烯微球粒径及其分布的影响

采用分散聚合工艺制备微米级单分散聚苯乙烯微球，并对分散聚合反应的内部影响因素(分散稳定剂、助稳定剂、单体、引发剂)进行了研究．结果表明，随着分散稳定剂和助稳定剂用量的增加，聚苯乙烯微球的粒径减小；随着单体和引发剂用量的增加，聚苯乙烯微球的粒径增大．分散稳定剂和单体用量是影响聚苯乙烯微球粒径分布的两个主要内部因素．     

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。     

室温沉淀聚合制备单分散聚苯乙烯微球

采用沉淀聚合的方法以乙醇/水为混合溶剂、K_2S_2O_8/NaHSO_3为引发剂,室温下引发苯乙烯聚合制备了单分散的聚苯乙烯(PS)微球.研究了反应时间、引发剂用量、反应溶剂中乙醇与水的比例、搅拌速度对聚苯乙烯微球的收率及形貌、单体转化率的影响.结果表明,聚苯乙烯微球的单体转化率、微球的收率和粒径随着反应时间的延长而增加,反应12 h后趋于稳定;当增加引发剂的用量,聚苯乙烯微球的单体转化率、微球的收率和粒径都有所增加,K_2S_2O_8与Na HSO_3用量分别在≤2.0%和1.3%时,能够得到单分散的聚苯乙烯微球;随着反应介质中水含量的增加,聚苯乙烯微球的单体转化率、微球的收率先增加后降低,单分散性变差,水含量在≤40%能够得到单分散的微球;搅拌速度从600 r/min增加到1200 r/min时,微球粒径、收率与单体转化率几乎没有变化.并初步研究了聚苯乙烯微球的形成机理.     

乙醇或乙醇-水为新的溶剂体系沉淀聚合制备单分散聚合物微球

以三羟甲基丙烷三丙烯酸酯(TMPTA)作交联剂,, 苯乙烯 (St) 作共聚单体,, 偶氮二异丁腈(AIBN)作引发剂,, 在低毒性乙醇和乙醇-水混合物这一新的溶剂体系中沉淀聚合反应4 h制备了单分散交联微球. 通过提高交联剂用量、引发剂用量和改变反应介质中水的用量探讨了提高单体转化率的方法. 结果表明,, 提高引发剂用量和增加溶剂中水的用量都能有效提高单体转化率并制得粒径均匀的微球. 保持其他条件不变,, 在乙醇中使用2 wt% AIBN仅能得到79%的单体转化率,, 提高AIBN用量至6 wt%或在介质中增加水的用量至28 vol%,, 在制得单分散微球的同时单体转化率可以达到95%以上. 文中对微球的形成机理和提高单体转化率的方法给出了理论解释.     

窄分散大粒径交联聚苯乙烯功能微球的合成研究

用分散聚合法，以聚乙烯吡咯烷酮（PVP）为稳定剂，偶氮二异丁腈（AIBN）为引发剂，乙二醇二甲基双丙烯酸酯（EGDMA）为交联剂，一次加料法在醇水介质中制备数个微米交联聚苯乙烯（PS）微球。研究了苯乙烯（St)、丙烯酸（AA）、EGDMA的用量对粒子大小，粒径分布的影响。测量了微球表面羧基的含量。     

Controllable Preparation of Monodisperse Polystyrene Microspheres with Different Sizes by Dispersion Polymerization

Summary: Monodisperse polystyrene (PS) microspheres with different sizes were prepared by dispersion polymerization in dispersion media of ethanol/water and isopropayl alcohol/water, respectively. The effect of polarity of the dispersion medium, stabilizer and initiator concentration on the average sizes and size range were evaluated. The results show that monodisperse PS microspheres with different sizes could be prepared in dispersion media of ethanol and isopropyl alcohol/water when appropriate initiator and stabilizer concentrations were employed, and the latter is a more appropriate medium to prepare uniform PS microspheres. It was found that the microsphere sizes reduced with increasing water content in the dispersion medium. Furthermore, in isopropyl alcohol/water dispersions, the average sizes decreased with increasing stabilizer concentration.     

Synthesis of monodisperse polystyrene microspheres by dispersion polymerization using sodium polyaspartate

We prepared monodisperse polystyrene microspheres by dispersion polymerization using sodium polyaspartate (PAspNa) as a dispersion stabilizer in an ethanol/water medium. The influence of reaction parameters, i.e., the volume fraction of ethanol in the medium, stabilizer concentration, and the monomer concentration, on the average diameter of the prepared polystyrene microspheres and its distribution were investigated. Polystyrene microspheres were successfully prepared, and the average diameter of the prepared monodisperse polystyrene microspheres was controlled by adjusting the reaction parameters. The zeta potential of the microspheres and the time course of conversion, the particle diameter and its distribution, and particle numbers were also examined. It was found that PAspNa as a dispersion stabilizer provides an environmentally benign process for the preparation of monodisperse polymer microspheres by dispersion polymerization.     

乙酸乙酯/乙醇混合溶液中分散聚合制备单分散亚微米级聚丙烯酰胺微球

以乙酸乙酯/乙醇混合溶液为分散介质, PVP为分散剂, 通过分散聚合法合成了单分散亚微米级PAM微球. 在反应初期, 自动加速现象明显. 由于凝胶效应的影响, 分子量随着单体转化率的提高而逐渐增大. 考察了分散剂浓度对最终产物增率的影响, 并用IR光谱对产物的结构进行了表征, 证明分散聚合体系中吸附稳定机理和接枝稳定机理同时存在, 且以后者为主. 同时还研究了混合溶剂比例、分散剂浓度、初始单体浓度和引发剂浓度对微球粒径及粒径分布的影响. 结果表明, 乙酸乙酯/乙醇体积比在5∶5-7∶3范围内, 可得到粒径在200 nm左右, 且分布较窄的PAM微球; 分散剂浓度增大, 粒径减小; 引发剂浓度增加, 粒径增大; 初始单体浓度较高或较低时, 都得不到单分散性微球.     

Monodisperse polystyrene microspheres prepared by dispersion polymerization with microwave irradiation

Monodisperse polystyrene microspheres with diameters of 200–500 nm were prepared by dispersion polymerization with microwave irradiation with poly(N‐vinylpyrrolidone) as a steric stabilizer and 2,2′‐azobisisobutyronitrile as a radical initiator in an ethanol/water medium. The morphology, size, and size distribution of the polystyrene microspheres were characterized with transmission electron microscopy and photon correlation spectroscopy, and the formed films of the polystyrene dispersions were characterized with atomic force microscopy. The effects of the monomer concentration, stabilizer concentration, and initiator concentration on the size and size distribution of the polystyrene microspheres were investigated. The polystyrene microspheres prepared by dispersion polymerization with microwave irradiation were smaller, more uniform, and steadier than those obtained with conventional heating. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2368‐2376, 2005     

分散共聚合制备PSt-AA-EGDMA功能性单分散微米级交联微球的研究

以苯乙烯(St)为主单体,丙烯酸(AA)为功能单体,乙二醇二甲基双丙烯酸酯(EGDMA)为交联单体,聚乙烯吡咯烷酮(PVP)为稳定剂,偶氮二异丁腈(AIBN)为引发剂,乙醇/水混合溶剂为分散介质,用分散聚合法一步合成了功能性单分散大粒径(10～20μm)交联聚苯乙烯微球.研究了PSt-AA-EGDMA三元分散共聚合体系的动力学,由转化率-时间关联得到动力学方程;R_p=k[I]^0.13([St]^1.87+[AA]^0.13+[EGDMA]^0.2)·(1+[PVP]^0.2)exp(-E/RT).详细讨论了AA,EGDMA,PVP的浓度和溶剂极性对羧基分布的影响,阐述了AA和EGDMA对粒子形态、粒径及粒径分布的影响.     

Preparation of monodisperse polystyrene microspheres: effect of reaction parameters on particle formation,and optical performances of its diffusive agent application

There are three monodisperse polystyrene (PSt) microspheres, 1.10, 3.13, and 5.21 um in diameter were prepared by dispersion polymerization in ethanol/iso-propanol media. 2,2′-azobis(isobutyronitrile) (AIBN) and poly(acrylic acid) (PAA) were utilized as initiator and steric stabilizer, respectively. The effects of the PAA stabilizer, AIBN initiator, St monomer, and EtOH solvent on particle size and size distribution were reviewed in this article. Besides, optical properties including total transmittance (T%) and transmittance haze (H%) were performed when these three monodisperse PSt microspheres were applied as diffusive agents. The results were examined in terms of total interface area in a system, and came up an optimal situation between transmittance haze (H _max% = 65%) and T% when total surface area of particles is around 45,000 cm².     

Preparation of Monodisperse Cationic Microspheres by Dispersion Polymerization of Styrene and a Cation-Charged Monomer in the Absence of a Stabilizer

Cationic polystyrene (PS) microspheres with monodispersity were prepared by dispersion polymerization of styrene and [2-(methacyrloyloxy) ethyl] trimethylammonium chloride (METMAC) in methanol/water system. The effects of METMAC, styrene, and initiator concentration as well as solvent composition on the diameters and size distribution of PS microspheres were systematically investigated. The results indicated that monodisperse cationic PS microspheres could be generated at METMAC concentration less than 2 mol% relative to styrene amount, and too high or low styrene amount was unfavorable to produce cationic PS microspheres. Moreover, it was found that with initiator concentration increasing, the average diameter and the size distribution of cationic PS microspheres also markedly increased. Solvent composition played a significantly important role in the preparation of cationic PS microspheres by dispersion polymerization of styrene and METMAC. Finally, the possible growth and stabilization mechanism of cationic PS microspheres was proposed. The electrostatic repulsion derived from positive charge on the surface of PS microspheres was responsible for the stabilization during dispersion polymerization in the absence of a stabilizer.     

Preparation of monodisperse poly(St‐co‐PETEA) microspheres by precipitation polymerization using ethanol as solvent

Precipitation polymerization of styrene (St) was carried out with pentaerythritol tetraacrylate (PETEA) to produce monodisperse crosslinked microspheres. A much safer ethanol replaced acetonitrile as a solvent in precipitation polymerization of monodisperse crosslinked poly(St‐co‐PETEA) microspheres. Monodisperse crosslinked microspheres with high monomer conversion were achieved within 4 hr. Uniform and well‐separated monodisperse were obtained in ethanol when PETEA concentration varied from 30 vol% to 90 vol% and the particle diameter decreased from 0.75 to 0.58 µm. The particle yield increased from 36.51 to 64.38% by increase in the initiator loading from 1 to 8 wt%. No coagulum occurred between particles when the polymerization time varied from 2 to 10 hr. Copyright © 2010 John Wiley & Sons, Ltd.