Size Determination of Ultra Fine Particles and Molecular Assembly in Supercritical Fluids

光子相关光谱法是一种能在几秒钟内测定纳米级微粒尺寸的强有力的原位分析技术。我们尝试了用光子晶体散射仪测量高压液体和超临界流体中的颗粒尺寸.制作了具有耐压圆柱形光散射池和高精度蓝宝石管的PCS。结果表明，采用5 μ L进样环的进样器，可以像常规液相色谱一样进样悬浮在甲醇中的微粒.为了进行耐压泄漏试验，研究了压力对尺寸测量的影响。在298 K、30 MPa的甲醇介质中，测量了粒径分布较窄的硅溶胶颗粒，其粒径与常压下的测量结果基本一致。这一事实表明，PCS可用于测量高分散的亚微米颗粒的尺寸 ...更多信息 压力和高密度相。当使用在甲醇中的聚苯乙烯胶乳颗粒时，在压力仅增加到1MPa期间，颗粒尺寸增加到标称直径的1.2倍，然后在2至30MPa的压力范围内几乎恒定。可以得出结论，聚苯乙烯聚合物可以在相对较低的压力下与甲醇溶胀.在20 MPa和313 K下对超临界CO2中聚苯乙烯乳胶粒的粒径测量结果表明，随着时间的延长，观测到的乳胶粒粒径增大，计算得到的多分散指数也变大。实验结果表明，聚苯乙烯乳胶粒子团聚速度较快，但在超临界CO2中的甲醇溶液作为样品澄清时的溶液，无法确定甲醇对聚苯乙烯乳胶粒子团聚的影响.在20 MPa和313 K下，通过Lobe方法估计的甲醇和二氧化碳的二元混合物的粘度与在混合物溶剂中由PCS测量计算的粘度相当一致，并且在二氧化碳含量小于60体积%的区域，根据颗粒尺寸假设与纯甲醇中的值相同。从这项研究中，纯溶剂或混合溶剂的粘度可以通过具有已知尺寸的均匀颗粒的PCS来测量。然而，这种测量方法的关键方面是选择合适的探针颗粒，这些颗粒在溶剂中形成稳定的悬浮液以了解粘度。少

Photon correlation spectruscopy (PCS) is one of the poweful in situ techniques to determine size of fine particles of nanometer order within a few second analysis time. We tried the size measurement of particles dispersed in high pressure liquid and supercritical fluid by using PCS.1. PCS was made, which had the pressure-resistant cylindrical light scattering cell with a high precision sapphire tube. It was found that an injector with a 5muL sampleloop could be used to injectparticles suspended in methanol, as usual way of a conventional liquid chromatography.2. The effect of pressure on the size measurement was carried out, with the purpose of the leak test for the pressure-resistant. Colloidal silica particles with a narrow size distribution in methanlo were measured under up to 30 MPa at 298K.The observed particle diameter agreed with the size measured at an atmospheric pressure. This fact indicates PCS could be used as the size measurement of sub-micron particles dispersed in high … More pressure and high dense phase.3. When polystirene latex particles in methanol were used, the particle size increased to 1.2 times larger than the nominal diameters during the pressure increased only up to 1 MPa, and then was almost constant under the pressure ranges from 2 to 30 MPa. It might be concluded that polystirene polymer could swell with methanol at the relatively low pressure.4. The results of the size measurement of polystirene latex particles in supercritical carbon dioxide at 20 MPa and 313 K indicated that the observed particle diameters increase with time and the calculated polydispersed indexes also become large. We concluded the polystirene latex particles agglomerated quickly, but could not determined the effects of methanol in supercritical carbon dioxide on the particle agglomeration, which was used as the solution at the sample preparation.5. The viscosity of the binary mixure of methanol and carbon dioxide at 20 MPa and 313 K estimated by Lobe's method was fairly agree with the viscosity calculated from PCS measurements in the mixture solvent and from particle size assuming same value as in pure methanol, at the region of less carbon dioxide content than 60 volume %.6. From this study, the viscosity of the pure or mixture solvent can be measured by PCS with uniform particles known size. However, the crucial aspect of this measuring method is the selection of suitable particles for a probe which form a stable suspension in the solvent to know the viscosity. Less