Development of Novel Scattering and Reflection Techniques for the Study of Dynamics in Polymer Assemblies at Interfaces

点击翻译按钮获取中文摘要

To detect and clariy the specific dynamics in polymers at interfaces, especially polymer monolayer on water surface, we have developed a novel instrument, Surface Dynamic Light Scattering (SDLS). First, we investigated the nanostructure of polymer monolayer on water by utilizing X-ray reflectometrer. The polymer used for monolayer preparation was poly (silacyclobutane)- b-poly(methacrylic acid), which was synthesized in our laboratory. As a result, we found that the hydrophilic layer under water surface is not a simple brush layer but it composed of two layers, i.e. carpet-like layer with high polymer density and polymer brush layer. The carpet layer is thought to be formed to avoid contact between hydrophobia layer and water. Its thickness was almost 15Å independent the polymer chain length and surface pressure. This is a quite novel finding. The brush layer became thicker under high pH condition. Also, salt effect for brush layer structure was also investigated.SDLS instrument was de … More signed with the principle of heterodyne optical system. By a try-and-error, we found that a beam splitting by grating is the best method for SDLS optics. Next, we found that the small vibration of the instrument table has a large effect for SDLS data. Hence, we introduced an active vibration-isolation table for instrument, and it was confirmed that this arrangement is fine for our purpose. A piezo-insulator was installed in the instrument to produce a small artificial wave on water surface system. Typical amplitude was 1 micrometer and the typical frequency was in the range of 100-300 Hz. This surface wave was clearly detected by our SDLS and we obtained the time correlation function with oscillation. This oscillation is a response from polymer monolayer on water. When the frequency 100Hz was added, we observed response frequency at 100, 200, 300 Hz. However, when 200Hz wave was added by piezo, only 100Hz response was observed. This means that the polymer monolayer has a characteristic viscoelasticity. Hence it was confirmed that the SDLS instrument we have developed can be used to obtain quantitative information for monolayer on water surface. Less