Facile preparation of self-assembled polymer nanotubes by proton beam irradiation

We report the self-assembled nanotube formation and its polymerization from a sugar-based amphiphile 1 having a diacetylene functional group by proton beam irradiation. The self-assembled nanotubes were staibilized by photoreaction without the induction of any morphological changes. To further verify the polymerization of the self-assembled organic nanotube 1, we carefully measured the FT-Raman spectrum to examine changes in the diacetylene moiety of the self-assembled 1 by proton beam. After irradiation by proton beam for 30 s, the vibrational band for the diacetylene group at 1481 cm(-1) (V(C triple bond C)) completely disappeared whereas a new band appeared at 1510 cm(-1), which corresponds to the C = C stretching vibration region. This finding indicates that the irradiation method by proton beam is useful not only to polymerize self-assembled nanostructures with no morphology changes, but also to synthesize new functional nanomaterials.