Kinetics and Dynamics of Pressure-induced Phase Transition in Amphiphilic Systems

两亲性分子如表面活性剂和脂类与油和水具有不同的半微观尺度结构。由AOT （aerosolo - ot）、水和癸烷组成的三元微乳液在常温常压下呈油包水的液滴结构，随温度或压力的升高而分离为两相。为了阐明这些跃迁的机理，进行了中子自旋回波实验。结果可以解释为压力诱导转变和温度诱导转变的微观起源不同。用小角中子散射法研究了由非离子表面活性剂C_<12>E_5、D_2O和辛烷组成的体系。温度和压力的影响与AOT相反。首次发现了压力诱导的六方相。采用小角中子散射和小角x射线散射的方法研究了DPPC水溶液在不同温度和压力下随乙醇的加入而发生的结构变化。在中等温度和压力下，首次发现了一个肿胀的凝胶相，其层状重复距离略大于已知相。

Amphiphilic molecules such as surfactants and lipids conform various semi-microscopic scale structures with oil and water. A ternary microemulsion composed of AOT (Aerosol-OT), water and decane has a water-in-oil droplet structure at ambient temperature and pressure, and separates into two phases with increasing either temperature or pressure. In order to clarify the mechanisms of these transitions, neutron spin echo experiments have been carried out. The results could be interpreted that the microscopic origins of pressure-induced and temperature-induced transitions are different.We also investigated the system composed of non-ionic surfactant C_<12>E_5, D_2O, and octane by mean of small-angle neutron scattering. The effects of temperature and pressure were opposite unlike the case of AOT. A pressure-induced hexagonal phase was shown for the first time.A structural change of an aqueous solution of DPPC with adding ethanol and varying temperature and pressure were investigated by means of small-angle neutron scattering and small-angle X-ray scattering. A swollen gel phase, in which the lamellar repeat distance is slightly larger than the known phase, was identified at moderate temperature and pressure for the first time.