title: Counterion-induced reversibly switchable transparency in smart windows.
abstract: Smart windows that can reversibly alternate between extreme optical characteristics via clicking counteranions of different hydration energies were developed on glass substrates through the facile spray-casting of poly[2-(methacryloyloxy)ethyltrimethylammonium chloride-co-3-(trimethoxysilyl)propyl methacrylate]. The optical transmittance was either 90.9% or 0% over the whole spectral range when alternately immersed in solutions containing thiocyanate (SCN(-)) or bis(trifluoromethane)sulfonimide (TFSI(-)) ions, respectively. The extreme optical transitions were attributed to formation of microporous structures via the molecular aggregation of polyelectrolyte chains bearing TFSI(-) ions in methanol. Because the smart windows were either highly transparent toward or completely blocking of incident light upon direct counterion exchange, this kind of nanotechnology may provide a new platform for efficiently conserving on energy usage in the interior of buildings.
authors.affiliation: Department of Organic Materials and Fiber Engineering, Soongsil University, Seoul 156-743, Republic of Korea.
authors.forename: Chang Hwan
authors.initials: CH
authors.lastname: Lee
authors.forename: Ho Sun
authors.initials: HS
authors.lastname: Lim
authors.forename: Jooyong
authors.initials: J
authors.lastname: Kim
authors.forename: Jeong Ho
authors.initials: JH
authors.lastname: Cho