Application of Polyimide Langmuir-Blodgett Films to Selective Gas Permeation

本研究旨在于多孔膜上制备聚酰胺LB膜，并探讨其气体渗透行为。这是Langmuir-Blodgett膜的一个新应用，该项目的问题之一是该过程需要乙酸酐和吡啶的处理，其中多孔基础聚合物（基底）应该对这种溶剂体系具有抗性。由聚丙烯制成的“Juragard 240”适合于此目的作为基膜。在此基础上成功地制备了用于气体渗透检测的聚酰亚胺LB膜。结果表明，随着膜层数的增加，膜的渗透数减小。因此，虽然渗透数受到层数的影响，但氮和氧的渗透比并不随层数的增加而显著变化。这意味着电影有少量的缺陷。因此，我们用电化学方法研究了聚酰亚胺LB膜中的缺陷。结果表明，聚酰亚胺LB膜的缺陷量明显少于普通脂肪酸LB膜。此外，改变聚酰亚胺的化学结构还可以改变聚酰胺LB膜中缺陷的数量，有些聚酰亚胺薄膜几乎没有缺陷。未解决的问题，氮和氧的比例，应该是未来的问题，在这种薄膜。

This research project aims to prepare polyamide Langmuir-Blodgett films on porous films, and examine gas permeation behavior of the films. This is a new application of Langmuir-Blodgett films.One of the problems of this project is that the process requires treatment of acetic anhydride and pyridine, where the porous base polymer (substrate) should have resistance to this solvent system. "Juragard 240" made by polypropylene was suitable for this purpose as the base film. Polylmide Langmuir-Blodgett films were successfully prepared on this base film, which applied to gas permeation examination. It was found that increasing with the number of layers, permeation number decreased. Thus, although the permeation number was influenced by the number of layers, the permeation ratio of nitrogen and oxygen did not change remarkably with increasing the number of layers. This meant the film had a small amount of defects. So, we examined the defect in polyimide Langmuir-Blodgett films using electrochemical method. The result indicated that polyimide Langmuir-Blodgett films had much less amount of defects compared with usual fatty acid Langmuir-Blodgett films. Further more, the number of defects in polyamide Langmtiir-Blodgett films changed by charging the chemical structure of polyimides, where some polyimides offered almost defect free Langmuir-Blodgett films. Unsolved problem, the ratio of nitrogen and oxygen, should be the future problem in such thin films.