无皂乳液聚合法合成阴离子PS微球及粒径控制

以苯乙烯(St)和丙烯酸(AA)为单体,过硫酸钾(KPS)为引发剂,采用无皂乳液聚合法合成了单分散阴离子聚苯乙烯(PS)微球,并对微球结构和影响单分散性的因素进行了研究。结果表明,AA单体也已共聚到聚合物链上,AA的加入使PS微球粒径减小,并赋予PS微球表面负电性;聚合反应的活化能为42.95kJ/mol,升高聚合温度提高了反应速率;随着KPS用量的增加,PS微球粒径减小,在用量为0.6%时呈现最好单分散性;随着反应介质中丙酮含量增加,聚合物在介质中溶解度增加,使PS微球粒径有所减小,但微球粒径分布有所变宽。     

单分散PS/PAA聚合物微球的研制

以苯乙烯为单体,采用分散聚合法制备了单分散性的聚苯乙烯(PS)微球,然后以PS微球作为种子、丙烯酸(AA)进行无皂种子乳液聚合制备了PS／PAA微球。考察了单体、引发剂、分散剂用量,反应介质极性和交链剂等因素对微球粒径大小及其分布的影响,探讨了分散聚合的反应机理。结果表明,通过改变反应工艺条件,能够制备粒径为1．0～3．0μm、单分散性很好的PS微球;通过无皂种子乳液聚合得到的核壳结构的PS／PAA微球粒径为2．50μm,多分散系数(PI)为0．0325,酸值为10．27mgNaOH／g,其表面带有羧基的特性能进一步扩大应用范围。     

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.     

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.     

带羧基单分散彩色微球的制备

采用两步活性溶胀种子聚合法, 制备了可用于免疫检测的3种不同颜色的表面带有羧基功能基的粒径在400—800 nm之间的彩色单分散微球. 先用无皂乳液聚合法制备出单分散聚苯乙烯种子, 然后用邻苯二甲酸二正丁酯(DBP)作为溶胀剂对微球进行溶胀, 溶涨后的种子模板再用混溶的苯乙烯、二乙烯苯、丙烯酸、双键彩色染料以及引发剂(BPO)溶胀, 升温聚合后得到理想的单分散微球. 考察了DBP和单体用量、各单体配比及染料对微球的形貌和单分散性的影响.     

一种聚苯乙烯荧光微球的制备及发光机理研究

以聚苯乙烯(PS)微球为基质,与乙酰氯通过Friedel-Crafts反应得到具有荧光性质的乙酰化聚苯乙烯微球(PS-AC).红外光谱(FTIR)分析表明苯环上已成功偶联了乙酰基.我们推测PS-AC微球的荧光现象是由聚苯乙烯分子链中的苯环与羰基双键通过π-π共轭形成的刚性平面结构引起的.为了验证该发光机理,以乙基苯和乙酰氯为原料通过Friedel-Crafts酰基化反应合成了一种与荧光微球发光基团具有相似结构的小分子化学物-对乙基苯乙酮.荧光发射光谱分析表明,对乙基苯乙酮与荧光微球在350~400 nm范围内激发光源的激发作用下都能在400~600 nm范围内产生稳定的荧光发射峰.而紫外-可见吸收光谱表明,与PS微球、乙基苯和乙酰氯相比,PS-AC微球与对乙基苯乙酮在300~400 nm范围内出现了新的吸收带,属于新形成的共轭体系的吸收.这种新的共轭体系可以将微球吸收的紫外光或紫光转变成可见的荧光.以上实验结果表明,本研究制备的荧光微球的发光现象是由苯环π键与羰基双键的共轭作用产生的.     

氯乙酰化聚苯乙烯型固相载体的制备

经聚苯乙烯(PS)微球的Friedel-Crafts酰基化反应制备了氯乙酰化PS功能化载体.避免了氯甲基树脂生产中使用氯甲醚等致癌物质,且消除了该生产中的二次交联及多取代等副反应.对催化剂、反应时间、酰基化试剂、PS微球的粒径及溶剂用量等反应条件进行了优化.得到担载量为4.6mmol/g的氯乙酰化PS,且在一定范围内,担载量可通过改变反应条件进行控制.     

量子点@SiO_2微球的水相合成及其在流式分析技术中的应用

通过表面配体交换将巯基硅烷包覆在量子点(QDs)表面,并与过量的硅烷共水解制备出包覆QDs的荧光硅球。该方法通过化学键合避免了QDs的泄露以及QDs荧光性质的改变,而且微球表面富集大量的巯基,为后续的反应提供活性位点。研究了反应时间、温度和搅拌速度对荧光微球形成的影响,优化条件得到了尺寸均一、单分散性的荧光微球。将荧光微球用于流式细胞分析检测,微球的数量和荧光强度能够满足流式分析检测的需要,适合制备成编码微球。     

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.     

Model filled polymers. VIII. Synthesis of crosslinked polymeric beads by seed polymerization

Monodisperse crosslinked polystyrene (PS) and polymethacrylate (PMA) beads of sizes greater than 1 μm in diameter are prepared by particle nucleation onto pre-existing polymer seeds in a multistage emulsion polymerization, in the absence of emulsifier. An adequate seed number concentration, which decreases with increasing seed size, is necessary to achieve monodisperse beads. Monodisperse multicomposition beads are prepared by polymerizing styrene onto PMA seeds, but not by polymerizing methyl methacrylate onto PS seeds. Phase separation in growing seed particles or surface polymerization following free radical capture may lead to the formation of asymmetric shaped particles.     

Preparation of fluorescent polystyrene microspheres by gradual solvent evaporation method

Highly cross-linked polystyrene beads of 9.2 μm were synthesized by seed polymerization with styrene as monomer and divinylbenzene as cross linker. Other sized monodisperse PS microspheres were also prepared by varying seed particle diameter and proportion of swelling agents. Furthermore, the polystyrene beads were stained by gradual solvent evaporation method using dyes such as rhodamine 101 and acridine orange. Gradual solvent evaporation method facilitates a high concentration of fluorescent dyes on beads. This is the key to obtain fluorescent beads with high intensity. The results showed that the fabricated fluorescent microspheres could be excited to various wavelengths (such as yellow, green, red and scarlet). Our synthesized microspheres offer high fluorescence emission efficiency compared to commercial fluorescent microspheres in the mean time have other properties in common.     

Synthesis of highly monodisperse quantum dot‐loaded polymer beads by impregnation and precipitation techniques

A novel approach to the synthesis of highly monodisperse quantum dot‐loaded polymer beads by combining impregnation and precipitation techniques was reported. The monodisperse poly(glycidyl methacrylate) (PGMA) beads were first synthesized by dispersion polymerization. Then, the PGMA beads were chemically modified to generate carboxyl groups, and impregnation of cadmium ions (Cd²⁺) inside the beads. Subsequently, the cadmium ions were reacted with thioacetamide to form cadmium sulfide (CdS) quantum dots within the polymer beads. The morphology, structure, and properties of CdS quantum dot‐loaded polymer beads were studied by field emission scanning electron microscope (SEM), transmission electron microscope, fluorescence spectrophotometer, fluorescence microscope, Fourier transform infrared spectroscopy, powder X‐ray diffraction, and thermogravimetric analysis. The results indicated that the CdS quantum dot‐loaded polymer beads had an average size of 1.4 μm, and were highly monodisperse. More interestingly, the CdS quantum dots distributed evenly within the polymer beads, which provide very strong fluorescence intensity. The existence of carboxyl groups on the quantum dot‐loaded polymer beads was measured quantitatively, and was found to be 0.2 mmol/g. These CdS quantum dot‐loaded polymer beads involving functional carboxyl groups would have potential applications in biological immunoassay and photoelectronic fields. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Monodisperse polystyrene particles crosslinked with poly(dimethyl siloxane) diacrylate using dispersion polymerization and their monomer swelling capability

A flexible poly(dimethyl siloxane) diacrylate (PDMSDA) crosslinker was synthesized using different molecular weights of poly(dimethyl siloxane) (PDMS, M _n =550, 1,700, 4,000 g/mol). The monodisperse polystyrene (PS) particles crosslinked with various contents of PDMSDA were prepared by dispersion polymerization, and applied as seed particles in the seeded polymerization. The crosslinking density of the PS particles was determined from the rate of transport of the monomer molecules to the crosslinked seed particles. It was confirmed that the monomer swelling capacity of seed particles and final morphological changes of polymer beads were determined significantly by the crosslinking density of the seed particles. In addition, the morphological change was not observed without the oligomer swelling step in the seeded polymerization due to the hydrophobic property of PDMS. When highly crosslinked seed particles were used in the seeded polymerization, peculiar morphology (doublet structure) of polymer beads appeared.     

High-throughput transformation of colloidal polymer spheres to discs simply via magnetic stirring of their dispersions

In this article, we have successfully demonstrated the high-throughput production of colloidal discs via magnetic stirring of aqueous dispersions of monodisperse, sulfate-stabilized polystyrene (PS) spheres in the presence of a good organic solvent. The organic solvent could be water-miscible, such as tetrahydrofuran, or water-immiscible, such as chloroform. Water-immiscible organic solvents were mixed into aqueous dispersions of PS spheres in the presence of sodium dodecyl sulfate. The geometry of the resulting discs could be easily adjusted by the magnetic stirring time and speed, the stirring bar weight, and the amount of organic solvent. Our strategy is simple, scalable, and hardly dependent on the nature of the organic solvent and the PS sphere diameter; PS spheres with diameters ranging from 200 nm to 5 μm were deformed into discs with almost 100% yield. When organic solutions of fluorescent dyes and nanoparticles were used instead of pure organic solvents for PS sphere liquefaction, fluorescent discs were obtained, underlining the effective, efficient encapsulation of the fluorescent substance in the discs.     

Preparation of micron-size monodisperse polymer particles having highly crosslinked structures and vinyl groups by seeded polymerization of divinylbenzene using the dynamic swelling method

Micron-size monodisperse polystyrene/polydivinylbenzene (PS/PDVB) composite particles having highly crosslinked structures and vinyl groups were prepared as follows. First, 1.9 m-size monodisperse PS seed particles produced by dispersion polymerization were dispersed in ethanol/water (70/30, w/w) solution which dissolved divinylbenzene (DVB) monomer, benzoyl peroxide as an initiator and poly(vinyl alcohol) as a stabilizer. The PS seed particles were swollen with a large amount of DVB monomers to 4.3 m in diameter while keeping good monodispersity by the dynamic swelling method, where water was slowly added, continuously, with a micro feeder into the dispersion. And then, the seeded polymerization of the absorbed DVB was carried out.Part CXXXV of the series Studies on Suspension and Emulsion     

静电层层自组装制备聚苯乙烯微球(核)/MCM-41纳米粒子(壳)阶层结构复合微粒

采用聚苯乙烯磺酸钠(PSS)和聚二烯丙基二甲基氯化铵(PDDA)两种聚电解质, 通过静电层层自组装成功地将MCM-41介孔二氧化硅纳米粒子包覆到聚苯乙烯(PS)微球表面. 实验结果表明, 当以尺寸为1.4 μm的PS微球为核时, 包覆了两个聚电解质双层(PDDA/PSS)2的PS(PDDA/PSS)2(PDDA/MCM-41)复合结构微粒与包覆了一个聚电解质双层(PDDA/PSS)的PS(PDDA/PSS)(PDDA/MCM-41)复合结构微粒相比, 复合结构微粒之间的交联程度降低, 但是MCM-41纳米粒子在聚苯乙烯微球表面的包覆都比较松散, 且产物中存在大量杂质. 而当以尺寸为5 μm的聚苯乙烯微球为核时, MCM-41纳米粒子紧密地包覆在聚苯乙烯微球表面, 复合结构微粒之间只有少量桥连物, 且产物中杂质很少.     

A Facile Method for Preparation of Polymer Particles Having a “Cylindrical” Shape

A facile and novel approach to prepare monodisperse polystyrene (PS) particles having a “cylindrical” shape was discovered. Spherical PS particles prepared by dispersion polymerization were stirred in a polyvinylpyrrolidone (PVP) aqueous solution for several hours using a magnetic stirrer at room temperature. In the presence of PVP, the spherical PS particles deformed into cylindrical shapes following stirring; however, the particles did not deform in the absence of PVP. The deformation rate of the particles was affected by the molecular weight of the dissolved PVP. This stirring method is not only highly efficient and high yielding, but also applicable to other materials such as polymethyl methacrylate. Moreover, the cylindrical particles were successfully applied as particulate surfactants in a Pickering emulsion system, which exhibited excellent stability in comparison to a system using spherical particles as a surfactant. In the first case, the emulsion was left standing for more than 4 months.     

Model filled polymers. IX. Synthesis of uniformly crosslinked polystyrene microbeads

Monodisperse sized crosslinked polystyrene (PS) beads prepared by reaction of styrene (S) and divinylbenzene (DVB), in batch emulsion copolymerization in the absence of emulsifiers, are not uniformly crosslinked, because DVB is more reactive than S. For copolymerization of 1 to 10 mol % DVB and S, within each crosslinked PS microbead, the crosslink density varies by a factor exceeding two and decreases with increased conversion. A semicontinuous copolymerization, involving incremental additions of DVB, produces uniformly crosslinked PS beads. For both copolymerization techniques, T_g correlates well with crosslink density and PS beads are spherical and monodisperse in size. © 1992 John Wiley & Sons, Inc.     

Influence of viscosity within polymerizing particle on the morphology of micron-sized,monodisperse composite polymer particles produced by seeded polymerization for the dispersion of highly monomer-swollen polymer particles

Micron-sized, monodisperse polystyrene (PS)/poly( n-butyl methacrylate) (PBMA) composite particles, in which PS domain(s) were dispersed in a PBMA continuous phase, were produced by seeded polymerization for the dispersion of highly n-butyl methacrylate (BMA)-swollen PS particles (PS/BMA=1/150, w/w) using various concentrations of benzoyl peroxide as initiator in the absence/presence of sodium nitrite (NaNO ₂) as a water-soluble inhibitor. The percentages of the composite particles having double, triple and over PS domains, which were thermodynamically unstable morphologies, increased with a rapid increase of viscosity within the polymerizing particle.