Nano-scale control of composite polymer films by mass-controlled layer-by-layer sequential adsorption of polyelectrolytes

The mass of polyelectrolyte films adsorbed onto a surface during the deposition of a thin polymer film by a layer-by-layer sequential adsorption process was systematically controlled using a feedback system with a computer. For the deposition process, a quartz crystal microbalance (QCM) with an integrated oscillation circuit was attached to the arm of an automatic slide stainer and the frequency shift during adsorption or rinsing of the polyelectrolytes was monitored by a computer attached to a frequency counter. By feeding back the data acquired by the in situ QCM measurement, the mass of material deposited was controlled and a high quality self-assembly film was produced. This method is termed mass-controlled layer-by-layer sequential adsorption. The accuracy of the layer thickness in the multiplayer film was found to be approximately 1 nm.