title: Surface morphologies of Langmuir-Blodgett monolayers of PEOnPSn multiarm star copolymers.
abstract: Star polymers composed of equal numbers of poly(ethylene oxide) (PEO) and polystyrene (PS) arms with variable lengths and a large (up to 38 total) number of arms, PEO(n)PS(n), have been examined for their ability to form domain nanostructures at the air-water and air-solid interfaces. All PEO(n)PS(n) star polymers formed stable Langmuir-Blodgett (LB) monolayers transferable to a solid substrate. A range of nanoscale surface morphologies have been observed, ranging from cylindrical to circular domains to bicontinuous structures as the weight fraction of the PEO block varied from 19% to 88% and n from 8 to 19. For the PS-rich stars and at elevated surface pressure, a two-dimensional supramolecular netlike nanostructure was formed. In contrast, in the PEO-rich star polymer with the highest PEO content, we observed peculiar dendritic superstructures caused by intramolecular segregation of nonspherical core-shell micellar structures. On the basis of Langmuir isotherms and observed monolayer morphologies, three different models of possible surface behavior of the star polymers at the interfaces were proposed.
authors.affiliation: Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: Ray
authors.initials: R
authors.lastname: Gunawidjaja
authors.forename: Sergiy
authors.initials: S
authors.lastname: Peleshanko
authors.forename: Kirsten L
authors.initials: KL
authors.lastname: Genson
authors.forename: Constantinos
authors.initials: C
authors.lastname: Tsitsilianis
authors.forename: Vladimir V
authors.initials: VV
authors.lastname: Tsukruk