沉淀聚合法Poly(DVB-co-EGDMA-co-MAA)功能聚合物微球的制备及表征

采用二乙烯基苯-55(DVB-55)和乙二醇二甲基丙烯酸酯(EGDMA)作为混合交联剂,乙腈为溶剂,偶氮二异丁腈(AIBN)为引发剂,以甲基丙烯酸为功能单体采用沉淀聚合法合成了单分散或窄分散的、表面具有羧基的交联聚合物微球,所得微球的粒径变化范围为0.6～3.8μm.通过调节交联剂DVB-55和EGDMA的投料比,可以对微球的粒径、粒径分布、产率、热稳定性以及表面官能团含量进行有效控制.文中对混合交联剂DVB-55与EGDMA比例的改变对微球的粒径、粒径分布以及产率的影响机理给出了理论解释;对DVB和EGDMA的兼容性研究表明,制备的三元聚合物微球的核拥有比投料比稍多的DVB单元,而微球的外层则以在预聚混合物中占更大比例的交联剂为主.     

壳聚糖修饰PLGA阳离子型纳米微球的制备与表征

采用单乳化-溶剂(O/W)挥发技术制备表面带正电荷的壳聚糖(CHS)修饰聚乙/丙交酯(PLGA)纳米微球(PLGA/CHS), 通过正交试验优化了纳米微球的制备条件. 结果表明, 微球粒径可控制在150～200 nm内, 在pH=4时, 纳米微球表面电位最高为55 mV. 影响微球粒径的主要因素是聚合物的浓度, CHS的分子量和浓度以及介质的pH值对微球表面电位也有明显影响. 制备粒径较小而表面电位较高的PLGA/CHS纳米微球条件为: ρ(CHS)=3 mg/mL, ρ(PLGA)=10 mg/mL, Vo/Va=1/4. SEM图像显示经CHS修饰的PLGA的纳米微球形状规整, 荧光显微观察和XPS分析结果证实CHS包覆于微球表面.     

不同尺寸单分散PMMA/GMA/DVB聚合物荧光微球的制备

采用无皂乳液聚合及种子无皂乳液聚合方法制备了200～800 nm四种不同尺寸的单分散PMMA/GMA/DVB (PMGD)复合微球. 用扫描电镜(SEM)和动态光散射(DLS)对粒径尺寸、形貌进行了表征. 实验发现单体滴加速度是影响种子无皂乳液聚合过程二次成核的关键因素. 用乙二胺对微球表面的环氧基团开环后, 通过在微球表面接枝树枝状PAMAM (d-PAMAM)达到微球表面的官能化的目的, 元素分析和红外光谱实验证明了微球表面d-PAMAM的存在. 最后利用微球表面的活性氨基与四甲基异硫氰酸罗丹明(TRITC)反应, 得到四种尺寸的水分散性的红色荧光微球.     

单分散聚苯乙烯微球的表面皱纹化

首先制备了不同粒径的未交联的单分散聚苯乙烯(PS)微球;而后通过离子溅射技术在PS微球表面沉积了一层均匀光滑的铂(Pt)壳层,得到了PS-Pt核壳结构的复合微球;最后借用溶剂溶胀法诱导微球表面起皱的发生,从而制备了表面带有皱纹微结构形貌的PS微球.系统考察了微球表面Pt层厚度(t)、微球粒径(D)、溶剂组成(即溶胀度)等因素对球面起皱和皱纹形貌的影响,获得了球面皱纹周期与Pt层厚度的指数关系;结合理论分析了其起皱行为,实验结果与理论分析相吻合.此外,将表面起皱与表面等离子体刻蚀技术相结合,实现了表面带有纳米点状凸起与皱纹复合微结构形貌的PS微球的可控制备.     

聚天冬酰胺衍生物对P(MMA-GMA-DVB)微球的修饰

用无皂乳液聚合法合成了不同交联剂含量(单体的20～50wt%)的表面带环氧基团的窄分散的P(MMA-GMA-DVB)(PMGD)复合微球,以L-天冬门酸为原料用磷酸催化溶剂法制备了聚琥珀酰亚胺(PSI),以N,N-二甲基甲酰胺为溶剂将PSI接枝到PMGD微球表面.元素分析结果证明,当微球中DVB的含量为40%时,微球表面修饰的PSI量最多.然后用乙二胺对微球表面剩余的PSI环进行开环,利用微球表面的氨基键合荧光素异硫氰酸荧光素(FITC),得到了荧光微球.     

聚苯乙烯/银核/壳复合微球的制备及其表征

通过分散聚合法制备了单分散性好,粒径均一的聚苯乙烯(PS)微球.以PS微球为核,用浓硫酸进行表面改性,使其表面带有负电.加入一定量的[Ag(NH3)2]+溶液,由于静电吸引,使其吸附在PS微球表面,通过化学还原的方法制备了PS/Ag核/壳结构复合微球.采用透射电镜(TEM)、扫描电镜(SEM)、红外光谱(IR)、X射线衍射(XRD)以及紫外-可见光谱对PS/Ag复合微球进行表征.结果表明:通过PS微球的表面改性,在其表面引入了磺酸基团,提高了微球表面的电负性和亲水性,对包覆过程起到了很好的促进作用;通过稳定剂(PVP)和不同还原剂(一缩二乙二醇DEG和乙二醇EG)的使用,形成的PS/Ag核/壳复合微球形貌不一样,同时研究表明制备出的PS/Ag复合微球可以用于催化剂催化还原有机染料溶液,表现出很好的催化活性.     

硫化物-高分子复合微球表面形貌与模板组成关系的研究

以N-异丙基丙烯酰胺(NIPAM)和甲基丙烯酸(MAA)为单体, 通过反相悬浮聚合法制备了多种MAA含量不同的阴离子型P(NIPAM-co-MAA)共聚微凝胶. 以这些共聚微凝胶为模板, 在不同表面活性剂存在下, 合成了一系列CuS(CdS、ZnS)-P(NIPAM-co-MAA)无机-有机复合微球材料, 研究了表面活性剂种类, 模板组成等因素对上述硫化物-高分子复合微球表面形貌的影响. 结果表明, 实验条件下所得复合微球表面均具有图案化结构, 该结构明显依赖于表面活性剂的种类和模板微凝胶的组成. 就模型体系而言, 随表面活性剂Span-20、Span-80和Span-85的HLB(亲水亲油平衡)值降低, 微球表面形貌趋于粗糙, 但仍然十分规整; 就模板组成而言, 模板中MAA含量增加使得复合微球的表面形貌变得更加精细. 据此, 认为通过选用合适的表面活性剂和微凝胶模板可以在一定范围内调控这些无机-有机复合微球的表面形貌, 从而为后续应用研究奠定基础.     

聚合物模板微球表面电性对中空二氧化硅微球形貌的影响

分别以过硫酸钾和偶氮二异丁基脒盐酸盐为引发剂,以聚乙烯吡咯烷酮(PVP)为分散剂,在水中引发苯乙烯聚合制备了2种表面分别带负电性和正电性基团的聚苯乙烯(PS)模板微球.在氨水催化下,利用正硅酸乙酯的水解缩合,形成PS/SiO_2复合微球,去除模板后得到中空SiO_2微球,并对其进行FTIR、电子显微镜、TGA以及氮气吸附等分析表征.结果表明,PS模板微球表面的电性决定了OH-的分布,从而导致PS模板微球表面SiO_2壳层不同的形成机制.当以表面带负电的PS微球为模板时,可得到树莓状的中空SiO_2微球;而以表面带正电的PS微球为模板时,得到是表面光滑的,具有介孔结构的中空SiO_2微球.     

草莓型PMMA/SiO2有机-无机复合微球的合成与表征

在纳米二氧化硅水分散介质中,借助于正离子单体甲基丙烯酰氧乙基三甲基氯化铵(MTC)与未改性纳米二氧化硅颗粒之间的电荷作用,通过MTC与甲基丙烯酸甲酯(MMA)的自由基共聚合,制备了草莓型的PMMA/SiO2复合微球.整个制备反应过程中,纳米二氧化硅无需表面处理,体系中无需另外加入乳化剂或助乳化剂,微球表面吸附的纳米二氧化硅对颗粒起稳定作用.详细讨论了纳米二氧化硅初始添加量、MTC浓度对复合微球的平均粒径、复合微球中二氧化硅含量及微球形态的影响.动态光散射粒度分布仪(DLS)测得复合微球粒径在180~300 nm之间,热重分析(TGA)表明复合微球中二氧化硅含量介于16.4%~40.8%之间.透射电镜(TEM)显示所得复合微球具有草莓型结构,二氧化硅于表面富集.     

二氧化钛纳米棒在空心微球表面的定向生长

通过表面预处理和水热法开展了用二氧化钛包覆空心微球的研究, 用扫描电子显微镜(SEM)和X射线衍射仪(XRD)等表征了所得产品, 并探索了各种反应参数对产物形貌和结构的调控作用. 实验结果表明, 空心微球的表面溶胶-凝胶预处理至关重要. 采用表面溶胶-凝胶技术预处理空心微球表面, 然后在一定条件下进行水热反应, 我们在空心微球表面上成功地包覆了垂直于微球表面并紧密排列的锐钛矿型二氧化钛纳米棒. 该材料质轻、耐腐蚀, 有望成为一种新型光催化剂, 应用于治理水体表面的大面积污染.     

Precipitation polymerization in acetic acid: synthesis of monodisperse cross-linked poly(divinylbenzene) microspheres

This paper reports two important results with cross-linked precipitation polymerization. (1) Acetonitrile, a substance harmful to human health, is the most commonly used solvent for the synthesis of cross-linked polymeric microspheres by precipitation polymerization. Here, the much safer acetic acid replaced acetonitrile as a solvent in the precipitation polymerization of monodisperse cross-linked poly(divinylbenzene) (PDVB-55) microspheres. Pumpkin-like particles and microspheres were obtained. XPS results displayed a significant amount of double bonds on the surface of the particles. The effect of monomer content, temperature, and initiator amount on the formed particles were studied. For a DVB loading below 1 vol % at 70 degrees C, monodisperse microspheres with smooth surfaces and narrow diameters were successfully obtained. With a DVB loading of 2 vol % and by observing the shapes of particles obtained with three different temperature(60, 70, and 80 degrees C), we found that more spherical particles were obtained at higher temperatures and pumpkin-like particles were obtained at lower temperatures. No significant differences in morphology or the coefficient of variation (CV) of the particles were obtained for different initiator loadings, whereas the particle diameters could be increased with increased initiator concentrations. (2) In order to obtain a better understanding of the formation mechanism of these particles, time-dependent experiments, for the first time, were conducted in a hydrophobic monomer system. By tracing the whole polymerization process, some important results were found. First, with the polymerization time at 70 degrees C, the particle diameters were found to increase from 800 nm to 3.0 microm, the CV displayed a decrease, and the amount of spheres and the spherical evenness of the particle surfaces improved. Second, by quantitatively calculating the particle number from the yields and diameters data, it is found that starting from 3.1% yield or two hours reaction time the total amount of particles in the system is almost a constant (about 9.6 x 10 (8)/L), which means that no homocoagulation occurred and no new particles were generated after nucleation, and there is a linear relation between cubic diameters and yields. These two results give us a distinct impression that particle growth almost comes from capturing of newly formed oligomers. Based on the above results, a scheme for the particle formation is proposed, which shows that that pumpkin-like particles are caused by a prolonged nucleation including the homocoagulation of primary nuclei. The growth of the particles includes two modes, an in situ surface polymerization of monomer and the adsorption of PDVB-55 oligomers. The differences between results in acetonitrile and in acetic acid (higher yields, smaller size, not spherical but pumpkin-like particles in acetic acid) were due to the lower solubilizability of acetic acid which is the so-called proton-containing solvent with the hydrogen bonding structure.     

A green protocol to prepare monodisperse poly(TMPTMA–styrene) microspheres by photoinitiated precipitation polymerization in low-toxicity solvent

To prepare monodisperse polymer microspheres under mild conditions, a green protocol is set up by means of photoinitiated precipitation polymerization. The work is carried out with three novel parameters, including: new type crosslinker of trifunctionality, low-toxicity solvent, and ambient temperature. Firstly, trihydroxymethyl propane triacrylate (TMPTMA) is selected as the most suitable crosslinker to prepare microspheres under ambient temperature, after comparing the morphology of its polymerization products with those of other two similar crosslinkers, i.e., trimethylolpropane triacrylate and ethoxylated trimethylolpropane triacrylate. In addition, as high as possible concentrations of TMPTMA and styrene are attempted to harvest the largest amounts of microspheres; however, a threshold of monomer concentration is found at 6 %. One kind of low-toxicity solvent, i.e., ethanol, is used as the reaction media to replace the commonly used toxic organic solvents, and it is proven to be the near Θ solvent for the present polymerization. Observation from scanning electron microscopy indicates that photoinitiation is an effective way to control the growth of microspheres, and highly monodisperse microspheres of 2.67 μm are achieved at polymerization time of 120 h. Finally, the reactive vinyl groups on microsphere surface are confirmed, which indicate that the microspheres from this green protocol is in favor of further functionalization and bio-medical application.     

Efficient synthesis of monodisperse,highly crosslinked,and “living” functional polymer microspheres by the ambient temperature iniferter‐induced “living” radical precipitation polymerization

The facile and efficient one‐pot synthesis of monodisperse, highly crosslinked, and “living” functional copolymer microspheres by the ambient temperature iniferter‐induced “living” radical precipitation polymerization (ILRPP) is described for the first time. The simple introduction of iniferter‐induced “living” radical polymerization (ILRP) mechanism into precipitation polymerization system, together with the use of ethanol solvent, allows the direct generation of such uniform functional copolymer microspheres. The polymerization parameters (including monomer loading, iniferter concentration, molar ratio of crosslinker to monovinyl comonomer, and polymerization time and scale) showed much influence on the morphologies of the resulting copolymer microspheres, thus permitting the convenient tailoring of the particle sizes by easily tuning the reaction conditions. In particular, monodisperse poly(4‐vinylpyridine‐co‐ethylene glycol dimethacrylate) microspheres were prepared by the ambient temperature ILRPP even at a high monomer loading of 18 vol %. The general applicability of the ambient temperature ILRPP was confirmed by the preparation of uniform copolymer microspheres with incorporated glycidyl methacrylate. Moreover, the “livingness” of the resulting polymer microspheres was verified by their direct grafting of hydrophilic polymer brushes via surface‐initiated ILRP. Furthermore, a “grafting from” particle growth mechanism was proposed for ILRPP, which is considerably different from the “grafting to” particle growth mechanism in the traditional precipitation polymerization. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

沉淀聚合制备聚(季戊四醇三丙烯酸酯-苯乙烯)单分散微球及其形成机理

以季戊四醇三丙烯酸酯(PETA)作交联剂,苯乙烯作共聚单体,偶氮二异丁腈作引发剂,在乙醇或其与水的混合溶剂中沉淀聚合制备了交联聚合物微球.研究了反应时间、交联剂用量以及溶剂中水含量对聚合过程及微球的影响.结果表明当PETA用量在单体质量的5%-35%之间且反应时间不低于6h时可制得单分散聚合物微球.当PETA用量低于20%时,所得微球的粒径随PETA用量的增加逐渐减小,粒径分布逐渐变窄;此后继续提高PETA用量,微球粒径又逐渐增大,粒径分布逐渐变宽.向反应介质中加入水,可明显提高微球产率及单体转化率,但其体积分数达30%时,所得微球分散性变宽.在此基础上对微球的形成机理也进行了讨论.     

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.     

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.     

单分散磁性P(St/BA/MAA)微球的制备

在共沉淀法合成超细磁流体的基础上 ,以苯乙烯 (St)、丙烯酸丁酯 (BA)和甲基丙烯酸 (MAA)为共聚单体 ,在不同的介质体系中采用无皂乳液聚合法制备了单分散 ,粒径范围为 80～ 2 30nm的磁性P(St BA MAA)微球 .详细探讨了介质极性、磁流体中表面活性剂含量对磁性高分子微球粒径和单分散性的影响 .实验结果表明 ,在一定范围内随介质极性降低 ,磁性高分子微球的单分散性提高 ,随表面活性剂用量增加 ,单分散性变差 .总体来看 ,磁性高分子微球的单分散性与其表面静电斥力密切相关 ,过大或过小的静电斥力均会导致磁性高分子微球单分散性的降低 .     

TNT分子印迹聚合物微球的合成与性能研究

以三硝基甲苯(TNT)为模板分子,EDMA为交联剂,采用沉淀聚合法制备了TNT分子印迹微球.讨论了溶剂用量、模板分子用量、功能单体种类等对分子印迹微球的形貌及吸附性能的影响;利用紫外吸收光谱和BET表征了印迹聚合物微球的结合位点相互作用与印迹孔穴结构;通过平衡吸附和选择性吸附实验,研究了印迹聚合物微球的吸附性能和选择性识别性能.结果表明,以丙烯酰胺为功能单体制备的分子印迹聚合物为规则的球形,内部含有分子印迹孔穴,微球的粒径为1～2μm.印迹聚合物微球可在30 min内达到吸附平衡,在1 mmol/L的TNT乙醇溶液中,印迹聚合物微球的平衡吸附量为32.5 mmol/kg,对TNT分离系数为25.19,具有较好的特异性吸附能力,并可选择性识别TNT分子.     

三羟甲基丙烷三丙烯酸酯-苯乙烯沉淀聚合高产率制备高交联单分散聚合物微球

以三羟甲基丙烷三丙烯酸酯(TMPTA)-苯乙烯(St)为单体,偶氮二异丁腈(AIBN)为自由基引发剂,通过在乙醇中的沉淀聚合可制得高交联单分散P(TMPTA-St)聚合物微球.对单体转化率,微球以及可溶性低聚物的产率进行了测试.结果表明,使用10 wt%至60 wt%的交联剂TMPTA进行聚合可获得单分散微球,产率在50%左右.增加TMPTA用量可提高微球产率和单体转化率.增加引发剂AIBN用量对提高微球产率也有促进作用,但同时可溶性低聚物产率也增加.向乙醇中加入水作为反应介质结合适当增加AIBN用量可使单体转化率达到98%,微球产率高于90%.对实验结果进行了解释,对聚合机理进行了讨论.     

Synthesis of polymeric microspheres based on 3‐chloro‐2‐hydroxypropyl methacrylate

In this study polymer microspheres were prepared by precipitation and dispersion polymerizations of CHPMA. The effect of polymerization solvent and type of stabilizer on the particle size, size distribution and yield was investigated. In the polymerization experiments two solvents: benzene and dipropyl ether and three stabilizers: MPEG 750, MPEG 5000, PVAc were used. The possible route to modify the surface of the microspheres to obtain epoxide groups was proposed.