聚苯乙烯在混合LB膜中的聚集行为

利用LB膜技术制备了聚苯乙烯(PS)和硬脂酸(SA)的混合薄膜.通过观察不同摩尔比例的PS与SA的π-A曲线,研究了SA与PS在空气-水界面的行为.利用紫外可见光谱(UV-Vis)及原子力显微镜(AFM)研究了PS在混合LB膜中的聚集行为.结果表明:PS的聚集现象不仅存在于空气-水界面上,而且它的聚集程度随着膜压的增加而变大.由于聚集程度与PS相的形貌有关,且PS的形貌随着时间而发生变化,也就是PS沉积到基片后,它的形貌发生变化,因此可通过控制膜压得到PS在混合膜中的特定形貌.

AFM study on self-aggregation behavior of polystyrene in mixed Langmuir-Blodgett films

The mixed Langmuir-Blodgett（LB） films of polystyrene（PS） and stearic acid（SA） with different ratios of PS monomer unit to SA molecule and at different deposition pressures were prepared.The occupied area per imaginary molecule at the air-water interface is larger than the calculation value derived from the additivity of the molecular areas of PS and SA.The above results indicated that the two components,namely PS and SA,should prefer to contact with themselves rather than with heteromolecules in the mixed Langmuir films.UV-vis spectra of PS in CHCl3 solution and in mixed PS/SA LB films demonstrated that PS molecules exist in the aggregation form in the mixed LB films.The phase separations of PS and SA in the mixed LB films were observed clearly by atomic force microscope（AFM） and this observation is in a good agreement with UV-Vis results.By observation the morphologies of the mixed PS/SA LB films with different ratios,we found that PS domains are surrounded by SA phases.AFM images of the mixed LB films deposited at different pressures clearly showed that the aggregations of PS molecules become thicker and denser with the increase of deposition pressures.By observing the time-dependent changes in the images of the mixed PS/SA LB films,we found that PS domains continue to self-aggregation with time after the mixed film deposition.