Layer-by-layer self-assembly (LbL) is one of the most elegant methods to create various functional materials such as electrical conducting, adsorption, optical and porous materials. The previous studies showed that the porous films using LbL were obtained by immersing dense weak- polyelectrolyte films into an aqueous solution with a specific pH value. We described a novel method to fabricate simply the porous polyelectrolyte film with metal ions; a dense structure transformed into the porous structure by immersing in specific metal ion solutions.<br/>The dense polyelectrolyte films composed of poly(allylamine hydrochloride) (PAH) / poly(acrylic acid) (PAA) were formed by the LbL technique. The porous PAH/PAA films with metal ions were obtained by immersing the dense PAH/PAA films in several concentrations of silver or copper acetate aqueous solutions. The pore size of porous PAH/PAA films were reduced with an increasing concentration of metal ion solution. In addition, the porous films with copper ions had the smaller pore size than these ones with silver ions (Figure 1). The porous transition of the novel method was caused by three phenomena: (a) the formation of a new bond between polyelectrolyte and metal ion, (b) subsequent ionic bond disruption and (c) re-formation (Figure 2).<br/>To the best of our knowledge, this is the first report that the pore size of the porous structure was controlled in the range from microscale (1-10 mm) to nanoscale (50-100 nm) by the concentration or types of metal ions among the reports of LbL technique. These porous films with high surface were available for various applications such as adsorption, separation, catalysis, and optics.

Structural control of self-assembled porous polyelectrolyte films by interaction with specific metal ions

251st National Meeting (2016)

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