title: AFM study of micelle chaining in surface films of polystyrene-block-poly(ethylene oxide) stars at the air/water interface.
abstract: A series of three-arm star block copolymers were examined using atomic force microscopy (AFM). These stars consisted of a polystyrene core composed of ca. 111 styrene units/branch with poly(ethylene oxide) (PEO) chains at the star periphery. Each star contained different amounts of PEO, varying from 107 to 415 ethylene oxide units/branch. The stars were spread as thin films at the air/water interface on a Langmuir trough and transferred onto mica at various surface pressures. Circular domains representing 2D micelle-like aggregated molecules were observed at low pressures. Upon further compression, these domains underwent additional aggregation in a systematic manner, including micellar chaining. At this point, domain area and the number of molecules/domain increased with increasing pressure. In addition, it was found that longer PEO chains led to greater intermolecular separation and less aggregation. These AFM results correspond to attributes seen in the surface pressure-area isotherms of the stars. In addition, they demonstrate the viability of AFM as a quantitative characterization technique.
authors.affiliation: The George and Josephine Butler Polymer Research Laboratory, Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Logan
authors.forename: Pascal
authors.initials: P
authors.lastname: Masse
authors.forename: Brian
authors.initials: B
authors.lastname: Dorvel
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Skolnik
authors.forename: Sergei S
authors.initials: SS
authors.lastname: Sheiko
authors.forename: Raju
authors.initials: R
authors.lastname: Francis
authors.forename: Daniel
authors.initials: D
authors.lastname: Taton
authors.forename: Yves
authors.initials: Y
authors.lastname: Gnanou
authors.forename: Randolph S
authors.initials: RS
authors.lastname: Duran