Preparation of Nano-sized Particles by Using a Centrifugal Force Field in Rotating Porous Media

本工作旨在通过在旋转多孔材料中快速混合含有反应物的液滴，以高生产率制备单分散纳米级颗粒。在第一年，我们表征了由NaCl-aq测试液形成的雾的分散（尺寸分布，电荷1等）。或PAO（聚α -烯烃）。去年对多相接触器的转轴进行了改进，使接触器在高转速下长时间稳定运行。将该新型接触器应用于MMA（甲基丙烯酸甲酯）乳液的微分散，然后用无机稳定剂进行悬浮聚合合成PMMA颗粒。将预搅拌好的MMA O/W悬浮液300 mL送入旋转多孔圆筒眼腔，最终在接触器出口处收集夹带的含有分散微乳液的水雾。经过多次严格的操作，在60℃下开始聚合MMA乳液，得到PMMA颗粒。然后，用激光衍射粒度仪测量了与最终乳液相对应的PMMA粒径分布。结果表明，该接触器的连续相条件（C_<表面活性剂>=0.02wt%, C_<稳定剂>=21.5wt%）适用。随着多孔圆筒转速的增加，微乳液的平均粒径逐渐减小到微米量级。此外，通过以1/2 ~ 1/10的O/W比稀释原始悬浮液，成功地将乳液的平均粒径降低至2μm。根据这些发现，我们得出结论，与传统方法相比，这种带有旋转多孔圆柱体的接触器具有以更高的生产率制备微米级乳液的潜力，通过连续馈送具有最佳分散成分的原始悬浮液。

The present work is aimed at preparing monodisperse nano-sized articles at a high production rate by mixing droplets containing reactants rapidly in rotating porous materials. In the first year, we characterized the dispersion of mists(size distribution, charge one, etc.) formed from test liquid of NaCl-aq. or PAO(poly alpha-olefin). In the last year, the rotating shaft of multiphase contactor was improved to operate the contactor stably at a high rotating speed for a long time. This renewed contactor was applied to the micro-dispersion of MMA(methyl methacrylate) emulsion, followed by the synthesis of PMMA particles by suspension polymerization with inorganic stabilizer. After 300 mL of the pre-stirred O/W suspension of MMA was fed into the eye space of rotating porous cylinder, the entrained mists containing dispersed micro-emulsion were eventually collected at the outlet of contactor. After a serious of operation was repeated several times, the polymerization of MMA emulsion was initiated at 60℃ to obtain PMMA particles. Then, the PMMA particle size distribution, corresponding to that of the final emulsion was measured with a laser diffraction particle sizer. As a result, it was confirmed that the conditions of continuous phase in the conventional method(C_<surfactant>=0.02wt%, C_<stabilizer>=21.5wt%) were applicable to the experiments with this contactor. The average size of micro-emulsion decreased from 100μm of that of initial fed emulsion eventually to micrometer order with the increase in rotating speed of the porous cylinder. Further, the average emulsion size was successfully lowered up to 2μm by diluting the raw suspension at O/W ratio of 1/2 to 1/10. From these findings, we concluded that this contactor with a rotating porous cylinder owns a potential to prepare micrometer-sized emulsion at a higher production rate than the conventional method, by continuously feeding the raw suspension that has an optimum compositions for the dispersion.