Self-assembly of maltoheptaose-b-PMMA block copolymer systems: 10nm Resolution in thin film and bulk states

This paper describes the self-assembly of oligosaccharide-based hybrid block copolymers (BCPs) consisting of maltoheptaose (MH) and poly(methyl methacrylate) (PMMA) into 10nm scale lamellar and cylindrical phases depending on the volume fractions of MH (ϕ_MH) and the annealing process. Time resolved SAXS study of the BCP bulk samples during thermal annealing indicated that the BCPs phase separate into 10nm scale periodical structures. The solvent vapor annealing induced self-organizations of the BCP into different phases depending on ϕ_MH and the weight fraction of THF/H₂O. BCPs with relatively higher Ø_MH, MH-b-PMMA_3k (ϕ_MH=0.27) and MH-b-PMMA_5k (ϕ_MH=0.16) self-organized into lamellar phases while the BCP sample with relatively lower ϕ_MH, MH-b-PMMA_9k (ϕ_MH=0.10), self-organized into cylindrical phase by using THF/H₂O=1/4 (w/w). On the other hand, the solvent vapor annealing with larger fraction of THF, i.e. THF/H₂O=2/3 (w/w), induced cylindrical phases for MH-b-PMMA_3k and MH-b-PMMA_5k.