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

Abstract

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 (ϕMH) 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 ϕMH and the weight fraction of THF/H2O. BCPs with relatively higher ØMH, MH-b-PMMA3k (ϕMH=0.27) and MH-b-PMMA5k (ϕMH=0.16) self-organized into lamellar phases while the BCP sample with relatively lower ϕMH, MH-b-PMMA9k (ϕMH=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-PMMA3k and MH-b-PMMA5k.