title: Structural control in thin layers of poly(p-phenyleneethynylene)s: photophysical studies of Langmuir and Langmuir-Blodgett films.
abstract: We present the relationship between the spatial arrangement and the photophysical properties of fluorescent polymers in thin films with controlled structures. Eight surfactant poly(p-phenyleneethynylene)s were designed and studied. These detailed studies of the behavior of the polymers at the air-water interface, and of the photophysical properties of their transferred LB films, revealed key structure-property relationships. Some of the polymers displayed pi-aggregates that are characteristic of an edge-on structure at the air-water interface. Monolayer LB films of these polymers showed greatly reduced quantum yields relative to solution values. Other polymers exhibited a highly emissive face-on structure at the air-water interface, and did not form pi-aggregates. The combination of pressure-area isotherms and the surface pressure dependent in situ UV-vis spectra of the polymers at the air-water interface revealed different behavioral details. In addition, the UV-vis spectra, fluorescence spectra, and quantum yields of the LB films provide design principles for making highly emissive films.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Jinsang
authors.initials: J
authors.lastname: Kim
authors.forename: Igor A
authors.initials: IA
authors.lastname: Levitsky
authors.forename: D Tyler
authors.initials: DT
authors.lastname: McQuade
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Swager
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D004987:Ethers / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry; D010777:Photochemistry; D011108:Polymers / Q000737:chemistry*; D019904:Polymethyl Methacrylate / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D000480:Alkynes; D004987:Ethers; D005456:Fluorescent Dyes; D011108:Polymers; D013501:Surface-Active Agents; C436384:phenyleneethynylene; D019904:Polymethyl Methacrylate