STUDY OF THE REORIENTATIONAL MOTION OF RODLIKE MICELLES BY ULTRASONICALLY INDUCED BIREFRINGENCE

本工作的目的是直接测量棒状胶束的取向弛豫时间，并利用超声诱导双折射的方法获得有关棒状胶束稳定性的新信息。改进了光探测器和光学系统，以测量超声诱导双折射(超声诱导双折射光谱)的频率依赖性。为了弄清超声诱导棒状胶粒的双折射，测量了赤铁矿溶胶和聚四氟乙烯(PTFE)胶乳超声诱导双折射的频率依赖性。在5~225 MHz的较宽频率范围内观察到双折射现象。对于棒状胶体颗粒，需要一种新的超声诱导双折射理论，将Oka理论与粘性流体中的转动扭矩相结合。合成了十六烷基二甲基胺氧化物(C16DMAO)，并测量了C16DMAO在20和50 mM水溶液中的超声诱导双折射，其双折射强度在10^&lt；-10；-9&gt；范围内，并且随着接近各向同性向列相转变点而增大。双折射与超声强度的平方根成正比，而赤铁矿溶胶和聚四氟乙烯胶乳的双折射与超声强度成正比。在本实验条件下，未观察到棒状胶束形状的变化。从瞬时双折射的轨迹观察到50 mm溶液的三个不同的取向弛豫过程，取向弛豫时间在0.03-0.04秒之间。这一过程可归结为棒状胶束的复杂纠缠运动。在低胶束浓度范围内，20 mm溶液在35和50ﾟC下的取向弛豫时间分别为0.31s和0.24s。

The purpose of this work is to directly measure the orientational relaxation times of rodlike micelles and to get new information about the stability of rodlike micelles by ultrasonically induced birefringence method. The light detector and optical system were improved to measure the frequency dependence of ultrasonically induced birefringence (ultrasonically induced birefringence spectroscopy). In order to clarify ultrasonically induced birefringence of rodlike colloidal particle, the frequency dependence of ultrasonically induced birefringence was measured for hematite sol and poly (tetrafluoroehylene) (PTFE) latex. The birefringence was observed in the wide frequencyrange from 5 to 225 MHz. A new theory of ultrasonically induced birefringence should be required for the case of rodlike colloidal particle combining the Oka theory with the turning torque in viscous fluids. The hexadecyldimethylame oxides (C16DMAO) were synthesized and ultrasonically induced birefringence was measured for aqueous C16DMAO solutions of 20 and 50 mM.The intensity of the birefringence was in the range 10^<-10>-10^<-9> and increased with approaching to isotropic-nematic phase transition point. The birefringence was proportional to the square root of ultrasonic intensity, while the those of hematite soland PTFE latex were proportional to the ultrasonic intensity. The change of shape of rod like micelles was not observed within our experimental condition. The three different processes of orientational relaxation motions of solutions of 50mM were observed from the trace of the transient birefringence and the orientational relaxation times lied from 0.03 to 0.04 sec. The processes are as cribed to the motion of the complicated entanglement of the rod like micelles. In the range of the low concentration of micelle, the single relaxation was observed and the orientational relaxation times for 20 mM solution at 35 and 50 ﾟC were 0.31 and 0.24 sec, respectively.