Reversible conformation-driven order-order transition of peptide-mimic poly(n-alkyl isocyanate) in thin films via selective solvent-annealing

We report for the first time the conformational and structural details of peptide-mimic poly(n-hexyl isocyanate) (PHIC). PHIC is a representative poly(n-alkyl isocyanate)s, which have received significant attention because of their unique stiff chain characteristics and potential applications in various fields. A well-ordered hexagonal close packing structure of PHIC with 8 ₃ helical conformation was clearly observed in the nanoscale thin films that were selectively annealed with carbon disulfide (CS₂). A well-ordered multi-bilayer structure of the polymer with β-sheet conformation was also clearly formed in the films that were selectively annealed with toluene. In addition, a fully reversible transformation between these two self-assembled structures was demonstrated by consecutive annealings with CS₂ and toluene.