Effect of assembly condition on the morphologies and temperature-triggered transformation of layer-by-layer microtubes

摘要

The morphology and temperature-triggered transformation of the LbL microtubes consisting of poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) were investigated as a function of assembly pH, polyelectrolyte molecular weight (MW), and multivalent ions. The as-made microtubes assembled at pH 5.5 (PAH)/5.5 (PAA) showed perforations on the surface, while those assembled at pH 7.5 (PAH)/3.5 (PAA) showed smooth surface without perforations. At the same MW, the microtubes assembled at pH 7.5/3.5 transformed more effectively compared to those assembled at pH 5.5/5.5. The aspect ratio of microtubes assembled at pH 7.5/3.5 decreased from 5 to 2 as the temperature increased from room temperature to 121 A degrees C. Furthermore, transformation of microtubes was facilitated as the MW of polyelectrolytes decreased. The dimensional stability of microtubes was influenced by the MW and added multivalent ions. These results were discussed in the context of the structure of the LbL assemblies.