Spin-assembled layer-by-layer films of weakly charged polyelectrolyte multilayer.

We investigate the effect of film deposition methods on the film properties of layer-by-layer assembled polyelectrolyte multilayers. Multilayered structures of linear polyethylenimine (LPEI) and poly(acrylic acid) (PAA) are prepared by using conventional dipping-based assembly as well as spin-assisted assembly. While the polyelectrolyte interpenetration by the diffusion motion of LPEI species is allowed in dipping-based assembly, an instantaneously and kinetically frozen phase of the film deposition is obtainable from spin-assisted assembly. Being kept from the interdiffusion of LPEI, a stratified internal structure is expected in the spin-assisted assembly, which is completely contrasted to the intermixed phase in the dipping-based assembly. The ability to control the inner structure of the multilayered film enables us to manipulate the physical properties or chemical activity of the functionalized thin films. We also demonstrate that the control over the strength of polyelectrolyte interdiffusion on a very top surface can be utilized for a quantitative manipulation on the degree of macromolecular self-assembly of nanomaterials.