Application of Polyimide Langmuir-Blodgett Films to Selective Gas Permeation

本研究的目的是在多孔膜上制备聚酰胺Langmuir-Blodgett膜，并考察膜的气体渗透行为。这是朗缪尔-布洛杰特膜的新应用。该项目的问题之一是该工艺需要对乙酸酐和吡啶进行处理，其中多孔的基聚合物(基材)应该具有对该溶剂体系的抵抗力。由聚丙烯制成的“Juragard 240”适合作为基膜。在此基础上成功制备了聚酰胺朗缪尔-布洛吉特薄膜，并将其应用于气体渗透检测。结果表明，随着层数的增加，渗透数呈下降趋势。因此，虽然渗透数受层数的影响，但氮氧渗透比并不随层数的增加而显著变化。这意味着薄膜有少量的缺陷。因此，我们用电化学方法检测了聚酰亚胺Langmuir-Blodgett薄膜中的缺陷。结果表明，聚酰亚胺Langmuir-Blodgett膜的缺陷比通常的脂肪酸膜要少得多。此外，聚酰胺Langmtiir-Blodgett薄膜中的缺陷数目通过改变聚酰亚胺的化学结构而改变，其中一些聚酰亚胺提供了几乎没有缺陷的Langmuir-Blodgett薄膜。尚未解决的问题，氮氧比，应该是这种薄膜未来的问题。

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.