二步种子溶胀法制备氯霉素分子印迹聚合物微球及其识别性能

以聚苯乙烯乳液为种球、氯霉素为模板分子、甲基丙烯酸为功能单体、二甲基丙烯酸乙二醇酯为交联剂,采用二步种子溶胀法制备了单分散氯霉素分子印迹聚合物微球(MIPMs).通过扫描电镜(SEM),考察了溶胀比、搅拌速度、水油比、交联剂用量、分散荆用量等对MIPMs形态,粒径大小及粒径分布的影响.并用静态吸附实验考察了微球的吸附识...     

种子溶胀悬浮聚合法制备分子印迹聚合物微球的研究进展

分子印迹聚合物微球是一种具有特异性识别性能的新型高分子材料.种子溶胀悬浮聚合法所制备的印迹聚合物微球可应用于极性环境中,能够满足诸如酶模拟等实际应用环境的要求.本文综述了几种不同的制备分子印迹聚合物微球的种子溶胀悬浮聚合法,并对其研究方向做了展望.     

种子溶胀法制备单分散交联聚苯乙烯微球

采用分散聚合法制备了聚苯乙烯(PS),并以此作为种子,与溶胀剂和单体、交联剂的混合物经二步溶胀聚合法,制备了单分散交联PS微球.讨论了溶胀剂用量、交联剂用量和单体用量对溶胀微球粒径和粒度分布的影响,以及交联剂用量对溶胀微球形貌的影响.结果表明,当溶胀剂的用量为3 g,交联剂为1 g,单体用量为7 g时可制得平均粒径为6.84 μm且单分散性较好的交联PS微球.     

种子溶胀聚合制备苯乙烯-二乙烯苯多孔交联微球

以苯乙烯分散聚合制备单分散种子微球(PS),再用超声分散改进的二步种子溶胀聚合制备了聚苯乙烯-二乙烯苯(PSt-DVB)多孔微球。用光学显微镜、扫描电镜(SEM)和比表面积孔径分布测定仪(BET)等对种子微球和多孔微球的表面形貌及孔结构进行了表征。结果表明,随分散介质极性的增大,所得PS种子微球的粒径变小,相对分子质量增大;固定种子微球用量,随着DBP和DVB用量的增加,交联微球比表面积上升、孔径下降。以乙醇为介质制备种子微球,当DBP体积为1.0 mL,DVB体积为8~10 mL时,能够得到4~7μm单分散性良好的多孔PSt-DVB微球。     

种子溶胀法制备单分散多孔聚合物微球的溶胀动力学研究

以微米级聚苯乙烯为种球,进行了两步种子溶胀法制备多孔聚合物微球的溶胀动力学研究,用光学显微镜、马尔文粒度分析仪、扫描电镜(SEM)和比表面积孔径分布测定仪(BET)等手段,对微球的溶胀形貌和孔结构进行了表征,优选出较好的溶胀条件是:以邻苯二甲酸二丁酯为溶胀剂,用超声乳化方式制备乳液,单位质量种球所用溶胀剂量为1.5mL,在35℃下10h即可完成溶胀,得到粒径分布良好的活化微球。研究发现,超声乳化分散方式的引入,可将溶胀时间由传统的24h缩短至10h,这可能是由于超声波的空穴效应所产生的巨大磁场加速了溶胀平衡状态建立的缘故。     

种子溶胀法制备聚甲基丙烯酸酯类微球

以分散聚合法制得的单分散聚苯乙烯微球为种球,采用改进的两步种子溶胀法制备了粒度均一、高交联、多孔的聚甲基丙烯酸缩水甘油酯-乙二醇二甲基丙烯酸酯微球,并系统探索了稳定剂种类和浓度、活化剂用量、溶胀倍数、致孔剂的种类及比例对微球形态和粒径分布的影响,同时用光学显微镜、扫描电镜、红外光谱及高效液相色谱对微球进行了表征。结果表明,以2μm和4μm的聚苯乙烯微球为种球,当活化剂与种球质量比为4,溶胀倍数为20~40倍,致孔剂为体积比为6∶4的环己醇和甲苯混合溶剂,以质量分数0.2%的羟丙甲基纤维素(以整个体系质量计,下同)为稳定剂时可制得粒径5μm和10μm的单分散高交联多孔的聚甲基丙烯酸酯类微球。     

溶胀法制备高强度聚苯乙烯荧光及编码微球

通过对荧光微球制备的传统溶胀法的改进,以二氯甲烷作溶胀剂,0.25%SDS水溶液作分散体系(促进疏水性染料溶胀进入种子微球以增加微球荧光强度),制备出了荧光强度高,单分散性好(平均粒径3.6μm,变异系数3.7%),光学性质稳定,定量染色的绿色、橙色、红色三种荧光微球。将发生荧光共振能量转移的两种染料同时溶胀进种子微球中,制备了能产生双荧光信号的荧光编码微球。     

活化溶胀法大粒径聚甲基丙烯酸甲酯微球的制备

探讨了活化溶胀法制备大粒径聚甲基丙烯酸甲酯（PMMA）微球的方法。首先用无皂乳液聚合法制备了中位径为0．21μm的PMMA种子微球。然后以正庚烷为活化剂、以十二烷基硫酸钠（SDS）为乳化剂进行活化溶胀,再以单体甲基丙烯酸甲酯（MMA）和引发剂偶氮二异丁腈（AIBN）对活化微球进行溶胀,溶胀平衡后升温进行聚合反应,制得了中位径为0．77μm的PMMA微球。     

多孔聚合物微球的制备及其在化妆品中的应用进展

简要介绍了单分散多孔聚合物微球的应用,重点综述了多孔聚合物微球用作化妆品活性物载体时所起的控释和缓释作用;讨论了多孔聚合物微球的合成手段,包括悬浮聚合法、分散聚合法和种子溶胀法,种子溶胀法中的动态溶胀法和二步溶胀法更易得到粒径均一的多孔聚合物微球;同时介绍了其成孔机理和性能表征;最后提出了多孔聚合物合成以及在化妆品应用中目前存在的问题、发展方向和应用前景。     

二步溶胀法制备大粒径共聚物乳胶粒子

以聚乙烯基吡咯烷酮(PVP)作为分散剂,以偶氮二异丁腈(AIBN)作为引发剂,在以水为溶剂的体系中以苯乙烯为单体制备出纳米级种子微球;然后利用二步溶胀法再分别以苯乙烯(St)和甲基丙烯酸甲酯(MMA)为单体,进而制备出微米级的核壳型微球。运用动态激光光散射仪对粒子半径的进行表征,其中以甲基丙烯酸甲酯为单体所制备核壳型微球粒子的半径为953 nm;以苯乙烯为单体所制备核壳型微球粒子的半径为808 nm。     

On activated seed swelling technique

The activated seed swelling technique is one of the promising methods in synthesis of micron‐sized monodispersed polymer particles. However, there are some parameters (eg the interference of acetone residue on particle swelling) that make this method difficult to carry out and even lead to a broad particle‐size distribution. Here, these parameters are studied and how to control them is discussed. The polydisperse seed swelling appeared at lower concentration of acetone and with incomplete evaporation of acetone from the system. The monodisperse swelling and larger particle sizes were achieved at higher concentration of acetone and longer evaporation time using a vacuum pump. These results suggest that the particle size and particle‐size distribution in the activated seed swelling technique can be controlled by the carrier (acetone) and the hydrophobe concentration in aqueous medium before and after the swelling process. Copyright © 2005 Society of Chemical Industry     

Molecular selectivity of tyrosine-imprinted polymers prepared by seed swelling and suspension polymerization

Tyrosine-imprinted microspheres have been prepared in an aqueous system by seed swelling and suspension polymerization, using trimethylolpropane trimethacrylate (TRIM), acrylamide (AM) as well as methacrylic acid (MAA), linear polystyrene and toluene as crosslinker, functional monomers, seeds and porogens, respectively. The size distribution proved to be greatly influenced by the ratio of water:TRIM (W/T) and the concentration of dispersant. When W/T was 46:1 (v/v), 4.6% (by mass) of poly(vinyl alcohol) (PVA) was used as dispersant, the molar ratios of tyrosine, MAA, AM and TRIM were 1:8:8:17, the polymer beads had the better size monodispersity, and the average size was 135 µm, while the sizes of the pores on the beads surfaces ranged from 1.25 µm to 9.0 µm. The adsorption behaviour and molecular selectivity of the beads were analysed using liquid chromatography; the results showed that the adsorption behaviour of the beads followed the rule of Langmuir, and the value of saturated absorption was 0.197 mmol g⁻¹. The tyrosine-imprinted polymers exhibited an inherent selectivity for tyrosine; when phenylalanine was used as the competing molecule the separation factor α was up to 1.91. However, the control polymers did not have this special molecule-selection capability, and the relative separation factor β was about 1.82 compared with the imprinted polymers. © 2002 Society of Chemical Industry     

Synthesis of snowman-shaped microparticles by monomer swelling and polymerization of crosslinked seed particles

Nonspherical snowman-shaped micro-sized particles were synthesized via monomer swelling and the polymerization of crosslinked seed particles. Monodispersed crosslinked polystyrene microspheres and methylmethacrylate were used as seed particles and the swelling monomer, respectively. Methylmethacrylate (MMA) induced crosslinked polystyrene microparticle swelling; however, compared to polystyrene, MMA is relatively hydrophilic. As a result, phase separation was observed, resulting in monomer-swollen, cross-linked particles protruding from the surface of the seed particles. By changing the monomer-to-particle weight ratio from 4 to 8, the ratio of the size of the head to the body of the snowman-shaped particles was varied from 0.3 to 0.7. The morphologies of the snowman-shaped particles were predicted using Surface Evolver software, and the simulation was applied to show the unique self-organization morphologies of snowman-shaped particles. We synthesized snowman-shaped microparticles by swelling and polymerizing cross-linked PS seed particles with methylmethacrylate. The monomer-swollen, cross-linked particles exhibited protrusions from the surface of the microparticles due to the phase separation of seeds from the particles. The size of the protrusion or head of the snowmanshaped particles was controlled by changing the monomer-to-particle weight ratio during the swelling process. Simulations were applied to estimate the aspect ratio of snowman-shaped particles and their self-assembled morphologies.     

Preparation and adsorption selectivity of deltamethrin molecularly imprinted polymers by two-step seed swelling method

Deltamethrin (DM) is one of the most efficient pyrethroid insecticides, which is widely applied to the control of insect pests in tea. In this work, efficient molecularly imprinted polymers (MIPs) were synthesized using DM as the template and acrylamide as the functional monomer, in conjunction with two-step seed swelling polymerization. Scanning electron microscopy, Fourier transform infrared spectroscopy, and Brunauer–Emmett–Teller surface area analysis confirmed the staggered pore structure and the presence of binding site in DM MIPs. The adsorption properties of the DM MIPs were also investigated based on assessing equilibrium adsorption as well as kinetic modeling and solid-phase extraction. Isothermal equilibrium adsorption experiments show that the adsorption behavior is consistent with the Freundlich and Halsey models, indicating heterogeneous multilayer specific adsorption. Fitting of the kinetic data demonstrates that chemical adsorption could be the rate-limiting step in DM extraction, which is consistent with a pseudo-second-order kinetic model. Using the imprinted polymers as solid-phase extraction filler, the DM recoveries from various teas were greater than 80% and exceeded those of the structural analogs cypermethrin, lambda-cyhalothrin, and bifenthrin. These results confirm that the MIPs exhibit specific adsorption of this analyte. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47415.     

Tyrosine imprinted polymer beads with different functional monomers via seed swelling and suspension polymerization

Molecularly imprinted polymers (MIPs) in bead form were prepared by seed swelling and suspension polymerization with trimethylolpropane trimethacrylate (TRIM) as crosslinker and tyrosine as template. The appearance of the beads was found to be greatly influenced by the concentration of polyvinyl alcohol (PVA) used as dispersant and the ratio of water to TRIM (W/T) during polymerization. When W/T was 46:1 (V/V) and the concentration of PVA‐water solution was 4.6 (%m/m), the result was more desirable size distribution with fewer misshapen beads. A series of imprinted polymers with methacrylic acid (MAA), acrylamide (AM), 2‐vinylpyridine (VP) and 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) as functional monomers (FM), respectively, were prepared, where the molar ratio of tyrosine, FM and TRIM was chosen as 1:16:17. The molecule adsorbing and selecting analysis of the polymers showed that although all the imprinted polymers adsorbed the templates following the rule of Langmuir and exhibited an obvious molecule selecting capability compared with their control polymers (CP), the adsorbing constant and the separating factor were much different when the functional monomers varied. AMPS worked better than the other FM in the present work with a higher value of asymptotic maximum solid phase concentration (0.282 mol/kg), adsorbing constant (198.81/mol), and a larger separating factor (1.93) when phenylalanine was used as the competitive molecule.     

溶剂与溶胀促进剂对神华煤溶胀行为的影响

采用体积法研究了甲苯、四氢萘、甲醇、二甲亚砜、N,N-二甲基甲酰胺(DMF)和乙醇胺(MEA)5种纯溶剂及1∶1的MEA-DMF混合溶剂对神华烟煤的溶胀行为,考察了Fe(NO3)3、Fe2(SO4)3和FeSO4添加量为0.5%(以铁占煤质量计)作为溶胀促进剂的性能。结果表明:MEA-DMF混合溶剂的溶胀效果优于5种单一溶剂。铁盐Fe(NO3)3明显促进煤溶胀,在80℃,24h和剂煤比5∶1条件下MEA-DMF混合溶剂与Fe(NO3)3协同可使溶胀率超过3.0。对溶胀处理后的神华煤FT-IR表明DMF、DMF-MEA溶胀处理以及与Fe(NO3)3协同溶胀处理后明显削弱了煤羟基氢键间的缔合作用,其中,经DMF-MEA与Fe(NO3)3协同溶胀处理的这一变化最为明显。     

Polyelectrolyte swelling of polyamidobenzimidazole

Conclusions An extreme character of the swelling of PABI fibres in DMAc-water mixtures has been detected. The maximum is observed in the region of a 10% water content.The peculiarity in swelling has been explained by the manifestation of a polyelectrolyte nature of the polymer.Translated from Khimicheskie Volokna, No. 5, pp. 34–35, September–October, 1987.     

Cyclic swelling of clays

Changes in free swelling and swelling pressure of different types of clays in response to varying cycles of wetting and drying have been studied. It can be shown that cyclic tests lead to a gradual destruction of the durable contacts in the clay structure and their transformation into less durable ones. At the same time, a reconstruction of the structure of the clays takes place, manifested by the destruction of large micro-aggregates and by disorientation of structural elements. All these phenomena result in great swelling with increase in the number of wetting cycles. Between cycles 3 and 20 the expansibility is at its maximum and may be 1.3–10 times as much as that after one wetting cycle. Cyclic swelling leads to an overall equilibrium in the system, when the internal energy of the clay is minimal and the bound water content is at its maximum. Clay in this state exhibits its maximum moisture uptake (W′_s), the meaning of which is of thermodynamic character and depends neither on the initial soil density and moisture, nor on the scheme of cyclic tests adopted.