Polyimides Langmuir-Blodgett films

Fu]iwara I, Ishimoto C and Seto J 1991 Scanning tunnelling microscopy study of a polyimide Langmuir-Blodgett film J. Vac. Sc/. Technoi. B 9 1148... 

Alignment of nematic liquid crystals by polyimide Langmuir-Blodgett films. Table 11, M. Murata, H. Awaji, M. Isurugi, M. Uekita and Y. Tawada, Japanese Journal of Applied Physics, 31, pp. L189-L191 (1992). Reproduced by permission of Institute of Pure and Applied Physics. 

Section II of this paper contains a description of the mechanism of NEXAFS spectroscopy, experimental setup and the types of information that can be obtained. Section III presents examples of work by others which serve as an important basis for the interpretation of our studies, and also several experiments on oriented polymer films and Langmuir-Blodgett films. Section IV describes a study of the chemical interaction that takes place when chromium metal is evaporated onto spun polymers, including polyimide. Section V describes the results of a study of poly(amic acid) films grown by epitaxy on clean surfaces of copper and chromium, and the effect of annealing to induce imidization. 

Fujiwara et al [51] have used molecular dynamics simulations to interpret the images obtained from STM experiments. The combined use of these two techniques is proving to be a very powerful tool for understanding the conformation of polymer films on surfaces. They showed that the individual polyimide strands observed were aligned parallel to the deposition direction of the Langmuir-Blodgett film. 

Systems that employed HREELS for interfacial-composition determinations included poly(ethylene oxide)-polystyrene diblock copolymer on Si wafers formaldehyde poly(oxymethylene) films on Cu(lOO) and Langmuir-Blodgett films of 4,4 -oxydianiline-pyromellitic dianhydride polyimide on Au and on highly ordered pyrolytic graphite. 

The Langmuir-Blodgett films (LB films) of polyimides deposited on substrates prove to be useful for aligning FLC molecular axes parallel to the transfer direction without rubbing. High-quality alignment promoting the appearance of bistable states has been reported [136]. 

It is therefore understandable that the first HREELS measurements were performed on Langmuir-Blodgett ordered layers, thin polyimide films and conducting polymers (2). Nowadays, almost any polymer surface could be analyzed with HREELS. 

Mono- and multilayer films of polyimides were successfully prepared using Langmuir-Blodgett technique. Monolayer films of polyamic acid long alkylamine salts were prepared at the air-water interface. The mono-layer films were deposited on appropriate plates to produce multilayer films of the precursor to polyimide films. Finaly, the polyimide multilayer films were obtained by treatment of the multilayer films of the polyamic acid amine salts with acetic anhydride and pyridine. The polyimide multilayer films had excellent coating ability giving a very smooth surface. They also exhibited insulating characteristics as reliable as polyimide thick films. 

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