微米级PS-PEDOT核壳型导电微球的合成与拉曼表征

以分散聚合法制备的微米级聚苯乙烯(PS)微球为模板、3,4-乙烯二氧噻吩(EDOT)为单体、过硫酸铵(APS)为引发剂,通过氧化聚合制备了PS-PEDOT核壳型复合导电微球。采用扫描电镜、透射电镜等对导电微球的形貌和结构进行了表征,重点采用拉曼光谱研究了其核壳结构特征。并研究了超声分散、溶液pH以及单体配比对导电微球形貌的影响。实验结果表明:超声的引入可提高导电微球的单分散性,改善微球的形貌。随着pH的降低或单体配比的增加,导电聚合物在PS微球表面的负载量随之增加,当m(EDOT)/m(PS)由0.60增加到1.25时,导电微球的平均粒径由1.76μm增加到1.91μm。     

Morphology of micron-sized monodispersed composite polymer particles produced by seeded polymerization for the dispersion of highly monomer-swollen polymer particles

 Monodispersed polystyrene (PS)/poly(n-butyl methacrylate) (PBMA) composite particles having 9.4 μm in diameter were produced by seeded polymerization for the dispersion of highly n-butyl methacrylate (BMA)-swollen PS particles, and their morphologies were examined. The highly BMA-swollen PS particles (about 150 times the weight of the PS seed particles) were prepared by mixing monodispersed 1.8 μm-sized PS seed particles and 0.7 μm sized BMA droplets prepared with an ultrasonic homogenizer in ethanol/water (1/2, w/w) medium at room temperature. After NaNO₂ aqueous solution as inhibitor was added in the dispersion, the seeded polymerization was carried out at 70 °C. In an optical microscopic observation, one or two spherical high contrast regions which consisted mainly of PS were observed inside PS/PBMA composite particles. In the PS domain, there were many fine spherical PBMA domains. Such morphologies were based on the phase separation of PS and PBMA within the homogeneous swollen particles during the seeded polymerization. Received: 04 June 1997 Accepted: 27 August 1997     

Synthesis and characterization of azoxystrobin hydrophilic molecularly imprinted microspheres

Abstract

In this research, hydrophilic molecularly imprinted microspheres (HMIPs) for azoxystrobin were successfully synthesized through precipitation polymerization. The adsorption capacities of HMIPs for azoxystrobin in water medium were higher than ordinary molecularly imprinted microspheres (MIPs), and HMIPs exhibited good hydrophilic properties. HMIPs and non-imprinted microspheres (HNIPs) were characterized by FT-IR, SEM, laser particle size analyzer and TGA. Comparing with HNIPs, azoxystrobin had a significant influence on morphologys and sizes of HMIPs. The Langmuir adsorption isotherm illustrated each binding site of HMIPs had the same adsorption capacity. The Lagergran pseudo-second-order kinetic model indicated the adsorption process between azoxystrobin and HMIPs was chemical adsorption. BET test illustrated HMIPs had bigger specific surface areas than HNIPs. Selective adsorption indicated that HMIPs had highly specific recognition of azoxystrobin. HMIPs successfully exhibited high selectivity and high hydrophilicity in water medium.     

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。     

微米级可降解性高吸水树脂微球的制备工艺

以淀粉与丙烯酸(AA)/丙烯酰胺(AM)为原料,采用接枝共聚的方法,在低油水比的反相悬浮体系中制备微米级可降解高吸水树脂微球,探讨了油水比、中和度、分散剂、引发剂、交联剂对树脂性能的影响.结果表明,对产物的粒径和吸水倍率影响程度由大到小依次为:丙烯酸中和度、油水比、分散剂用量、引发剂用量、交联剂用量.研究得到的最佳工艺条件为:丙烯酸中和度0.7,油水比2.5∶1,分散剂用量0.7g,引发剂用量(占单体总质量)0.3%,交联剂用量(占单体总质量)0.057%;得到产物的粒径约为1.5μm,吸水倍率为290.93g/g.     

Morphology of micron-sized polystyrene particles crosslinked with urethane acrylate

The morphology of micron-sized polystyrene particles crosslinked with a urethane acrylate crosslinker was studied with different concentrations of urethane acrylate and medium solvency by means of simple dispersion polymerization. The urethane acrylate employed as a crosslinker showed an excellent effect on maintaining the monodispersity of the polystyrene particles at a moderate crosslinker concentration (to about 5 wt%) in terms of the monomer-swellable surface of primary particles. By enhancing the medium solvency, the amount of urethane acrylate incorporated was increased, while the monodispersity of the final particles was maintained. It was believed that the increase in solvency on adding xylene to ethanol solution helped the diffusion of the styrene monomers into the primary particles. At high concentration of urethane acrylate, however, nonspherical particles, ellipsoidal or egg-like singlets and asymmetric doublets, were observed. The increased crosslinking density seemed to repel the styrene monomers during particle growth. Received: 30 June 1998 Accepted in revised form: 9 September 1998     

Monodisperse micron-sized crosslinked polystyrene particles. IV. Effect of network structure on polymerization procedure

Monodisperse micron-sized polystyrene particles crosslinked using urethane acrylate were produced by dispersion polymerization in ethanol solution and the effect of the crosslinked network structure on the polymerization procedure was studied. The influences of the concentrations of the initiator and urethane acrylate on the particle diameter (D _n), the particle number density (N _p), and the polymerization rate (R _p) were found to obey the approximate relationships D _n ∝ [initiator]^0.43 [urethane acrylate]^0.05, N _p ∝ [initiator]^−1.30 [urethane acrylate]^0.19, and R _p ∝ [initiator]^{0.24 ± 0.02}. The power-law dependence of D _n and N _p on the initiator concentration showed a similar trend to that of linear polystyrene reported in the literature. Especially, it was found that urethane acrylate does not have a serious effect on D _n and N _p of the particles produced. The dependence of R _p on the initiator concentration was observed to be higher than that of linear polystyrene, suggesting that there is still competition between heterogeneous polymerization and solution polymerization because of the crosslinked network structure of the primary particle. Received: 1 April 1999 Accepted in revised form: 29 June 1999