title: Controlling the size of nanostructures in thin films via blending of block copolymers and homopolymers.
abstract: The effects of molecular weight and concentration of poly (methyl methacrylate) (PMMA) homopolymer or symmetric short polystyrene-block-poly (methyl methacrylate) (PS-b-PMMA) diblock copolymer on the size of the nanostructures of its blends with symmetric long PS-b-PMMA diblock copolymer have been investigated by atomic force microscopy. By careful controlling of the film thickness, solvent selectivity, and annealing time, PMMA cylindrical microdomains oriented normal to the film surface were obtained in all thin films. With the addition of both low- and high-molecular-weight PMMA homopolymers, the cylindrical domain sizes increased although it was less obvious for the lower molecular weight homopolymer. In contrast to the homopolymer, adding the short chain diblock copolymer resulted in a decrease in the cylindrical domain size, which was ascribed to the reduction of the interfacial tension and increase in the stretching energy.
authors.affiliation: State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, People's Republic of China.
authors.forename: Juan
authors.initials: J
authors.lastname: Peng
authors.forename: Xiang
authors.initials: X
authors.lastname: Gao
authors.forename: Yuhan
authors.initials: Y
authors.lastname: Wei
authors.forename: Hanfu
authors.initials: H
authors.lastname: Wang
authors.forename: Binyao
authors.initials: B
authors.lastname: Li
authors.forename: Yanchun
authors.initials: Y
authors.lastname: Han