Layer-by-layer self-assembly and disassembly of single charged inorganic small molecules: towards surface patterning.

The patterning of layer-by-layer (LbL) polyelectrolyte multilayers with metal ions is important for the facile fabrication of circuits or selective catalysis. The strategy includes two issues: the incorporation of metal ions and their controlled assembly-disassembly, which require a good understanding of the assembly mechanism. Therefore, we explored the LbL assembly between a polycation, poly-(diallyldimethylammonium chloride) (PDDA) and an inorganic single charged molecule, [AuCl4](-), which could assemble at pH = 3.7 and disassemble at lower pH values. Moreover, we have demonstrated that the driving force in the assembly is a ligand-to-metal charge transfer interaction. Combining the controlled assembly-disassembly of PDDA-[AuCl4](-) multilayers and photolithography, we obtained a surface pattern of PDDA-[AuCl4](-) multilayers.