Transition of Ultrathick Polyamide Tubes into Vesicles with Great Stability

This work reports on the transition of a polyamide ultrathick wall microtubes to microvesicles through self-assembly. An amphiphilic polyamide is synthesized first by the solution polycondensation of sodium isophthalate-5-sulfonate (SIPA) and poly(propylene glycol) bis(2-aminopropyl ether) 2000. Then, its self-assembly in aqueous solution is investigated through direct hydration. The size and morphology of the self-assemblies is investigated by transmission electron microscope (TEM), scanning electron microscope (SEM), atomic force microscope (AFM), and optical microscope (OM) measurements. The result shows that the as-prepared polyamide first self-assembles to thick walled tubes, then these tubes can gradually evolve to ultrathick wall microvesicles with an unusually thick membrane above 330 nm. Both the transition pathway and the mechanism are investigated in micromicroscopy. Most importantly, the microvesicles show great thermal and chemical stability. The novel superstable self-assembly structures as well as the transition mechanism presented here offer a promising perspective for the application in the scope of the biological membrane movements and nanoelectromechanics in medical devices.