title: Synthesis, self-assembly and photophysical properties of oligo(2,5-dihexyloxy-1,4-phenylene vinylene)-block-poly(ethylene glycol).
abstract: We describe the synthesis and characterization of a family of diblock copolymers with 5 units of a dihexyloxy-phenylenevinylene block (OHPV) connected to a series of poly(ethylene glycol) (PEG) chains of different average lengths (12, 45 and 115 PEG units: OHPV5-b-PEG12, OHPV5-b-PEG45, OHPV5-b-PEG115). All three polymers underwent self-assembly in ethanol, a good solvent for the PEG units, but poor for the OHPV segment. The nature of the structures formed depends sensitively on the length of the PEG block. OHPV5-b-PEG115 formed long fiber-like micelles of uniform width, whereas OHPV5-b-PEG45 formed fragile broad ribbons. We also obtained thin ribbons with OHPV5-b-PEG12 but they tend to fold and twist upon themselves. The structures obtained were characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM), as well as by wide-angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC). In addition, their photophysical properties were examined by UV-vis, steady state fluorescence and fluorescence decay measurements. The results of these experiments indicate that the OHPV groups pack differently in the fiber-like micelles of OHPV5-b-PEG115 than in the lamellar structures formed by OHPV5-b-PEG45.
authors.affiliation: Department of Chemistry, University of Toronto, 80 St. George St, Toronto, ON, Canada M5S 3H6. mwinnik@chem.utoronto.ca.
authors.forename: Chun
authors.initials: C
authors.lastname: Feng
authors.forename: M Jose
authors.initials: MJ
authors.lastname: Gonzalez-Alvarez
authors.forename: Yin
authors.initials: Y
authors.lastname: Song
authors.forename: Isaac
authors.initials: I
authors.lastname: Li
authors.forename: Guangyao
authors.initials: G
authors.lastname: Zhao
authors.forename: Gregory
authors.initials: G
authors.lastname: Molev
authors.forename: Gerald
authors.initials: G
authors.lastname: Guerin
authors.forename: Gilbert
authors.initials: G
authors.lastname: Walker
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Scholes
authors.forename: Ian
authors.initials: I
authors.lastname: Manners
authors.forename: Mitchell A
authors.initials: MA
authors.lastname: Winnik