Study on the Molecular Motion in Organic Thin Film using Spin Probe Method and Molecular Dynamics

（一）.用自旋探针法研究了两亲分子在LB膜中的取向和分子运动.在不同温度下，测量了5-，10-和16-羟硬脂酸（DXSTA）及其与硬脂酸（STA）和聚烯丙基胺络合物的LB膜在不同磁场与膜法线夹角下的电子自旋共振谱，在分子运动可以忽略的液氮温度下，从角度依赖性确定了精确的分子取向及其分布。温度依赖性表明，亚甲基链的末端部分发生分子运动，而在这些LB膜中保持取向规则性。（二）、用自旋探针法研究了两亲分子在铸膜中的取向和分子运动，并将自旋探针法应用于具有两个长亚甲基链的四烷基氯化铵的铸膜。根据角度变化a ...更多信息 ESR谱的温度依赖性表明，在这些铸膜中，亚甲基链的各向同性运动是由尾部进行的，而亚甲基链的运动则保持在头基附近的取向。（三）、含探针分子的混合LB膜相分离条件的控制研究发现，在含doxyl硬脂酸和全氟癸酸的混合LB膜中，当doxyl单元的位置靠近头基时，不发生相分离。由于探针分子在水表面的单分子膜中的分子占有面积随着探针位置接近亲水基团而由于空间位阻而增加，因此认为探针分子之间的面内内聚力的降低是这种探针分子相分离特性的主要原因。（四）、用分子动力学方法模拟有机薄膜中的分子运动用分子动力学方法对这类体系的计算程序进行了改进，目前已基本达到可以用于实际研究的水平。结果表明，通过对含有自旋探针分子的LB膜的ESR谱及其分析，可以得到这些有机薄膜中分子运动的详细信息。少

(1). Elucidation of orientation and molecular motion of amphiphilic molecules in LB films by spin probe method.Electron spin resonance spectra for the Langmuir-Blodgett (LB) films of 5-, 10-, and 16-doxylstearic acids (DXSTAs) and their mixtures with stearic acid (STA) complexed with polyallyl-amine were measured at various angles between the applied magnetic field and the film normal at various temperatures, From the angle dependence at the liquid nitrogen temperature where molecular motion can be neglected, accurate molecular orientation and its distribution were determined. From the temperature dependence, it was shown that end part of methylene chain did molecular motion, while the orientation regularity is kept in these LB films.(2). Elucidation of orientation and molecular motion of amphiphilic molecules in cast films by spin probe method.The spin probe method was applied to cast films of the tetraalkylammonium chloride with two long methylene chains. From the angular variation a … More nd the temperature dependence of the ESR spectra, it was shown that the isotropic motion was carried out by the tail part of methylene chain, while the motion of the methylene chain kept the orientation in the vicinity of the headgroup in these cast films.(3). Control of phase separation condition of mixed LB films containing probe molecules.It was found that in mixed LB films containing doxylstearic acid and perfluorodecanoic acid phase separation did not occur when the position of doxyl unit is closer to head group. Since the molecular occupation area of the probe molecule in monomolecular film on water surface increases due to the steric hinderance as the probe position approaches to the hydrophilic group, it was suggested that that decrease in the in-plane cohesion force between probe molecules was a main cause for the phase separation characteristics of such probe molecule.(4). Simulation of the molecular motion in organic thin films using molecular dynamics methodThe calculation program of such system by the molecular dynamics method which had advanced the improvement until now reached the level which can be almost used for actual research. As the result, it is expected that detailed information can be obtained on the molecular motion in these organic thin films from the ESR spectra of LB films containing spin probe molecules and their analysis with this program. Less