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RESEARCH PRODUCT

Fine-Tuning of the film thickness of ultrathin multilayer films composed of consecutively alternating layers of anionic and cationic polyelectrolytes

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We have recently introduced a new method of creating ultrathin films [1–3] based on the electrostatic attraction between opposite charges. Consecutively, alternating adsorption of anionic and cationic polyelectrolytes leads to the formation of multilayer assemblies. Multilayer buildup is easily monitored by small angle x-ray scattering (SAXS). The total thickness of the multilayer assemblies increases linearly with the number of adsorbed layers, indicating a stepwise and regular deposition process. — Here, we report on the fine-tuning of the total film thickness by changing the ionic strength of the solvent from which the polyelectrolytes are adsorbed. When the anionic polyelectrolyte is adsorbed from solutions containing 1.0, 1.5, and 2.0 mol/l NaCl, the average thickness of each oppositely charged layer pair is precisely adjusted to 17.7 A, 19.4 A, and 22.6 A, respectively.