Dynamic Phase Transition and Crystallization Kinetics of Polymer Colloidal Crystals

虽然胶体晶体的相变和结晶动力学明显遵循经典的成核和晶体生长理论，但它们也与许多粒子的同步涨落现象密切相关。本研究改进了传统的间接观察方法，利用光学显微镜直接观察胶体晶体结晶过程中的平移扩散，分析了胶体晶体的动态相变。1. 单分散聚苯乙烯（0.3-2μm）胶体水悬浮液经离子交换树脂完全去离子6个月以上。2. 在以铂电极为电极，盖玻璃为底板的圆柱形电池中，用光学显微镜观察胶体结晶的时间分布。对记录下来的图像进行对比度增强等符号化处理，然后进行傅里叶变换。3. 利用傅里叶变换分析了胶体晶体中胶体粒子相互位置的相关性。4. 通过施加0.01 ~ 1hz的正弦电场对细胞进行平动扩散分析。5. 在胶体晶体的动态相变过程中，得到了多种粒子运动模式。这些模式与已有的动态光散射测量结果吻合得很好。

Though the phase transition and the crystallization kinetics of colloidal crystals apparently follow the classic nucleation and crystal growth theory, they are also related closely to the simultaneous synchronous fluctuation phenomena of many particles. In this study, improving the conventional indirect observation methods, the dynamic phase transitions of colloidal crystals are analyzed by the direct observation of translational diffusion in the course of crystallization by using optical microscope. 1. Monodispersed polystyrene (0.3-2μm) colloidal aqueous suspension is completely deionized by ion exchange resins for more than 6 months. 2. Time profiles of colloidal crystallization are observed by the optical microscope in originally designed cylindrical cell with platinum electrodes and a cover glass as the bottom plate. These images recorded are symbolized by the enhancement of the contrast, etc., and then they are Fourier transformed. 3. Correlation of mutual positions of colloidal particles of colloidal crystals is also analyzed using the Fourier transformation. 4. Translational diffusion is analyzed by the application of sinusoidal electric field (0.01-1Hz) to the cell. 5. Many modes of particle movement are obtained in the course of dynamic phase transition of colloidal crystals. These modes are agreed well with those already obtained by the dynamic light scattering measurements.