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

自旋探针法和分子动力学研究有机薄膜中的分子运动

基本信息

批准号：
08650971
负责人：
SUGA Kosaku
金额：
$ 1.34万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

项目摘要

(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

(1).用自旋探针法解析LB膜中两亲分子的取向和分子运动。测定了5-、10-和16-羟基硬脂酸（DXSTAs）及其与聚烯丙基胺络合的硬脂酸（STA） Langmuir-Blodgett （LB）膜在不同温度下的外加磁场与膜法向之间的不同角度下的电子自旋共振谱，从液氮温度下分子运动可以忽略的角度依赖中，确定了准确的分子取向及其分布。温度依赖性表明，在LB膜中，亚甲基链末端发生分子运动，而取向的规律性保持不变。用自旋探针法解析铸膜中两亲分子的取向和分子运动。采用自旋探针法制备了两长亚甲基链四烷基氯化铵的铸膜。从ESR光谱的角度变化和温度依赖性来看，亚甲基链的各向同性运动是由亚甲基链的尾部进行的，而亚甲基链的运动保持在头基附近。(3)含探针分子LB混合膜相分离条件的控制。研究发现，在含有羟基硬脂酸和全氟癸酸的混合LB膜中，当羟基单元的位置更靠近头基时，不会发生相分离。由于随着探针位置靠近亲水性基团，由于空间位阻的作用，探针分子在水表面单分子膜中的分子占据面积增大，这表明探针分子间面内内聚力的减小是导致探针分子具有相分离特性的主要原因(4)。用分子动力学方法模拟有机薄膜中的分子运动，使分子动力学方法的计算程序得到了很大的改进，目前已经达到了几乎可以用于实际研究的水平。因此，利用该程序对含有自旋探针分子的LB薄膜的ESR光谱进行分析，有望获得这些有机薄膜中分子运动的详细信息。少