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极性高分子多孔微球(EGPM)是由不同比例的甲基丙烯酸乙二醇双酯/甲基丙烯酸缩甘油酯和不同性质与组成的稀释剂存在下悬浮共聚合而制成。用堆积密度、骨架密度、比表面、孔径分布、溶剂吸收量、孔体积、床体积、平衡溶胀及扫描电镜等方法描述了微球的物化与孔结构性质。讨论了共聚多孔微球在聚合过程中致孔的关键——相分离与交联剂及稀释剂的相关性。从分子量-淋出体积标定曲线及对葡聚糖的分离谱图看,EGPM已具有现代亲水性快速凝胶色谱固定相的特征。此外还对水溶性高分子的分子量分散指数和其传质扩散作了初步的探讨。 相似文献
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Pore structure of the porous polydivinylbenzene microspheres is controlled by the degreeof crosslinkage and the diluent used. It is proved by chromatographic results that the higher thedegree of crosslinkage is, the more the micellar pores will be formed, and the nature as wellas the quantity of the diluent determine the real pore structure. Among the structural para-meters of the microspheres, the size and the pore diameter affect the performance in HPLCmostly. The linear sample capacity of the microspheres in 1--2 order of magnitude larger thanthat of the Silica-ODS. According to this result, it could be confirmed that the solute mole-cules penetrate deeply into the skeleton of the polymer network. Based on the polymeric struc-ture with the same chemical composition but different in pore structure, the contribution tothe retention of several organic compounds by Henry's and/or adsorption coefficient has beenstudied. The results obtained show that Henry's coefficient is approximately 80% of thetotal contribution, i. e. dissolution mechanism plays the main role in the chromatographicprocess, especially in case of polar compounds. The experimental result that the chroma-tographic separation relatively slightly depends upon the sueface area of the polymer isanother ovidence. It is better to define this kind of polymeric stationary phase as a sorbentrather than an adsorbent. From the point of view of dissolution mechanism, it is suggestedthat a homogeneous porous polymeric stationary phase constructed with chemically rigid ske-letal structure and sufficiently thin bulk polymeric phase inside the microspheres should bean ideal packing for chromatography. 相似文献
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用粒径约0.5微米季胺化单分散交联聚苯乙烯胶乳与粒径为5~30微米磺化交联聚苯乙烯共聚物微球藉库伦力附聚得到了阴离子交换树脂微球,并对磺化深度,基球和胶乳的粒径比以及交联度等对阴离子交换树脂附聚微球色谱性能的影响进行了分析。用这种阴离子交换树脂附聚微球作为HPIC分离柱的填料;用自制的全多孔强阳离子交换树脂YSG-SO_3H为抑制柱填料,仅用10厘米长的分离柱在约27分钟内即可使F~-、Cl~-、No_2~-、HPO_4~-、Br~-、No_3~-、及SO_4~-等阴离子混合样按顺序全分离。 相似文献
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利用空间排除色谱分离生物高分子,过去都是采用软的亲水性凝胶为柱填料。例如Bio-Gel P(交联聚丙烯酰胺)、Sephadex(交联葡聚糖凝胶)、Sepharose(珠状琼脂糖)、Bio-Gel A(琼脂糖凝胶)等。这些凝胶不能承受较高的柱压,一般只能在0.002-0.02厘米/秒的流速下操作,才能保持凝胶的机械稳定性。这个流速比高效液相色谱所通用的流速约低一个数量级。因此,达到分离平衡的淋洗时间较长,分离周期往往需要几小时。此外,这类软凝胶一般需要较大的进样量方能检出,如对蛋白质的检测就需要毫克级的量。 相似文献
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Polar polymeric porous microspheres of ethyleneglycol dimethacrylate/ glycidylmethaerylate (EGPM) have been synthesized by suspension copolymerization in the presence of diluent with different nature and composition. The correlation of phase separation with crosslinking agent and diluent which are the key points of pore formation during polymerization has been discussed. The physicochemical properties and the porous structure of the microspheres are characterized by apparent density, specific surface area, skeleton density, pore radius distribution, solvent regain, pore volume, bed volume, degree of swelling and the scanning electron microscopy. The molecular weight vs elution volume calibration curve and the chromatogram of dextran separation of the microspheres are also presented. Such a comprehensive evaluation of EGPM shows that it possesses the characteristics of hydrophilic stationary phase for modern gel permeation chromatography. Further, the molecular weight polydispersity and the solute mass t 相似文献
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聚二乙烯苯多孔微球的孔结构受控于交联度及稀释剂,从色谱方法证明交联度高对形成微束孔有利,而稀释剂的质和量则决定真孔的性质。微球的结构参数中以微球的尺寸及孔径对高效液相色谱性能影响较大。微球的试样线性容量比十八烷基硅氧烷键合硅胶大1—2个数量级,说明溶质分子是扩散进入到高分子骨架中的。文中以化学组成相同、孔结构不同的聚二乙烯苯微球为基础,研究了溶解及吸附对几种有机化合物的保留值的贡献,对极性溶质来说,溶解系数约占总贡献的80%。从许多实验结果也说明此类固定相的比表面对色谱的分离度贡献不大。因此称此种固定相为吸着剂较称之为吸附剂更好。可以设想,具有刚性骨架的高分子组成、高分子本体相又足够薄的均匀多孔微球将是一种较理想的固定相。 相似文献
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高活性和耐用性的甲醇氧化电催化剂对于直接甲醇燃料电池的商业可行性至关重要,然而,目前的甲醇氧化电催化剂与预期相去甚远,存在贵金属用量过多、活性平庸、衰减快等问题。在这里,我们报告了锚定在镍铁层状金属氢氧化物(NiFe-LDHs)表面Pt纳米颗粒复合材料,用于在碱性介质中稳定电催化甲醇氧化。基于Pt纳米颗粒的高固有甲醇氧化活性,与商业Pt/C催化剂相比,基底材料NiFe-LDHs在200,000 s循环测试后进一步增强了Pt的抗中毒能力和稳定性。NiFe-LDHs层板上单原子分散的Fe作为锚定位点将Pt纳米颗粒均匀分散在其表面,进一步充分利用了层状金属氢氧化物表面丰富的OH基团,促进邻近Pt位点上毒化中间体的氧化去除。这项工作突出了NiFeLDH在提高甲醇氧化反应整体效率方面的特殊性,为其他甲醇氧化电催化的设计和应用提供了指导。 相似文献
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