Quantitative analysis on the adsorbed amount and structural characteristics of spin self-assembled multilayer films

In this study, we demonstrate that the adsorbed amount of respective layers in spin self-assembled multilayer films can be controlled and predictable using an empirical power-law equation in terms of spin speed and initial solution concentration. The amount of a pair of polyelectrolytes deposited per bilayer rapidly increases with increasing polyelectrolyte concentration up to 12.5 mM while the solution concentration above 16 mM has no appreciable effect on the adsorbed amount. The adsorbed film thickness per bilayer is shown to be easily controlled from about 5 to 40 Å and proportional to constant power exponents of −0.34 and 0.78 with respect to the spinning speed (Ω) and the mole concentration of polyelectrolytes, respectively. We also demonstrate with synchrotron X-ray reflectivity measurement that the alternating organic/inorganic ultrathin films fabricated by the spin self-assembly process contain highly ordered internal structure and retain unique optical characteristics determined by the boundary condition at both the substrate/multilayer film interface as well as the multilayer/air interface.