6th International Symposium «Molecular Order and Mobility in Polymer Systems». Saint Petersburg, june 2-6, 2008.
SURFACE STRUCTURE OF LANGMUIR-BLODGETT FILMS OF COMB-LIKE RIGID-CHAIN POLYIMIDE PRECURSOR AND CORRESPONDING POLYIMIDE
S.I. Goloudina1, V.V. Rozanov2, V.M.
Pasyuta1, V.P. Sklizkova3, V.V. Kudryavtsev3
1St.Petersburg State Electrotechnical University, St.Peterburg, Russia
2Institute for Analytical In-strumentation, Russian Academy of Sciences, St.Petersburg, Russia
3Institute of Macromolecular Compounds, Russian Academy of Sciences, St.Petersburg, Russia
goloudina@mail.ru
Nanoscale films of polyimides formed as a result of prepolymer LB film imidization are used in creating micro- and nanoelectronic, optoelectronic and nanosystem devices. The polyimide films are quite promising in those fields of application since they are characterized by high thermal, chemical and mechanical resistance, and also since it is possible to form on a solid substrate nanolayers with thicknesses of 0.5 nm and more. To solve the problem of thin polyimide films fabrication with predictable characteristics it is of great importants to investigate the film surface structure and to understand its formation mechanism.
In the present work polyimide films were obtained by the thermal imidization of LB films of comb-like rigid-chain polyimide precursor (alkylammonium salts obtained from tert-amine o, o', o''- trihexadecanoyltriethanolamine and a polyamic acid based on dianhydride of 3, 3', 4, 4'- biphenyltetracarboxylic acid and o-tolidine (BPDA-oTD)).The LB film of polyamic acid alkylammonium salt (PAAS) contained 29 layers. Surface structure of LB films have been studied by the confocal laser scanning microscopy (CLSM) and atomic-force microscopy (AFM). The film surface was analyzed at different scales of the surface area, from larger scanning areas to smaller (from 50x50 to 1.5x1.5 mkm2 ). This allowed us to monitor variations in the surface structure morphology at different measurement scales and to characterize the film surface structural organization by going from the micro- to nanolevel.
Based on the CLSM and AFM measurements, we can separate out three levels of PAAS
LB film surface structural organization. The presence of light and dark regions,
as well as of light sports in the CLSM images character the PAAS LB films
heterogeneity at the micron level. At the sub-micron level, AFM is the most
informative method for the film relief characterization and interpretation of
heterogeneity observed in CLSM measurements. Further reduction of the image
scale makes it possible to reveal the domain-type structure of the prepolymer
and corresponding polyimide film surfaces and estimate the domain dimensions
(50-100 nm). The formation mechanism of the domain structure was proposed.
S.I. Goloudina, V.V. Rozanov, V.M. Pasyuta, V.P. Sklizkova, V.V. Kudryаvtsev Surface structure of Langmuir-Blodgett films of comb-like rigid-chain polyimide precursor and corresponding polyimide // 6th International Symposium «Molecular Order and Mobility in Polymer Systems». Saint Petersburg, june 2-6, 2008. Book of Abstracts, P-145.