XVI European Chemistry at Interfaces Conference. Vladimir, Russia, May 14-18, 2003 г.
FORMATION OF MONOLAYER AND LANGMUIR-BLODGETT FILMS OF COMB-LIKE SALT OF RIGID-CHAIN POLYAMIC ACID
Goloudina S.I.a, Sklizkova V.P.b, Pasyuta V.M.a, Luchinin V.V.a, Rozanov V.V.c, Klechkovskaya V.V.d, Bronnikov S.V.b, Gofman I.V.b, Kudryvtsev V.V.b
aS.Peterburg State Electrotechnical University, Russia,
bInstitute of Macromolecular Compounds, Russian Academy of Sciences, Russia,
cInstitute for Analitical Instrumentation, Russian Academy of Sciences, Russia
dInstitute of Crystallography, Russian Academy of Sciences, Russia
The possibility of preparation of ordered polyimide (PI) Langmuir-Blodgett (LB) films based on a comb-like polyamic acid salt (PAAS) with multilayer tertiary amine was investigated. Prepolymer was obtained from polyamic acid synthesized by using 3, 3¢, 4, 4¢-diphenyltetracarboxylic acid dianhydride with o-tolidine and tert-amine o, o¢, o¢¢-trihexadecanoyltriethanolamine. The structure of prepolymer and PI was studied by optical and atomic force microscopy (AFM), SAXS, electron diffraction and ellipsometry.
It was shown that PAAS forms well ordered stable monolayers at the air-water interface. Monolayers of tert-amine and PAAS showed phase transition at pressure 27 mN/m. From the compression isotherms, the area per monomer unit of PAAS in monolayer was calculated as 1.58 nm2 (Ao). This value corresponds to area calculation by the Alchemy program. The area of polymer unit at the moment of monolayer destruction (Ac) is close to the cross-section of tert-amine hydrocarbon chains bound to the PAA molecule (1.30 – 1.38 nm2).
PAAS monolayers were transported on the silicon substrate. Y-type of deposition was observed. Transfer coefficient was 1.0 - 1.1. X-ray diffraction pattern of the PAAS LB films has exhibited the Bragg-reflexion, which corresponds to the d-spacing of 5.48 nm. This coincides with the value calculated by the Alchemy program (5.60 nm). This shows that the LB films possess Y-type structure and that tert-amine aliphatic chains are oriented vertically in the layer.
Ellipsometry revealed that as a result of thermal imidization more densely packed polymer chains are formed. Refractive indexes of PI films formed with the aid of chemical and thermal imidization are markedly different. The surface morphology of PAAS and PI LB films was observed by AFM. 3, 7 and 29 layer LB films AFM images were obtained at different values of surface pressure and different types of imidization (thermal or chemical). The AFM images shows micro-domains of different size. Their diameters were analyzed statistically. As a result, micro-domains were shown to form a statistical ensemble described consequently with the model of reversible aggregation [1]. The distribution parameters, aggregation energy and mean diameter were revealed to depend on pattern preparation conditions. Proposals concerning mechanism of the domain formation were derived.
This work was supported in part by the RFBR, project № 02-03-32683.
1. H.G.R.Kilian, R. Metzler, and B.Zink, J. Chem. Phys., 107 (1997), 8697.
Goloudina S.I., Sklizkova V.P., Pasyuta V.M., Luchinin V.V., Rozanov V.V., Klechkovskaya V.V., Bronnikov S.V., Gofman I.V., Kudryvtsev V.V.Formation of monolayer and Langmuir-Blodgett films of comb-like salt of rigid-chain polyamic acid // XVI European Chemistry at Interfaces Conference. Vladimir, Russia, May 14-18, 2003, p.106