title: Stepwise Activation of Switchable Glazing by Compositional Gradient of Copolymers.
abstract: Thermotropic glazing is one of the most promising developments for adaptive solar control; however, a monotonic transparent-opaque transition limits its practical application. In this work, to render stepwise activation of the switchable glazing, we prepared multicomposition copolymers having a compositional gradient. By slow addition of the monomers in the reaction mixture during free-radical polymerization, the blend of copolymers with each polymer having different compositions of the monomers could be prepared. We found that the developed copolymers exhibit different thermal behaviors according to the monomer composition, yielding the nearly linear transmittance change over a wide temperature range due to the gradient hydrophilic-hydrophobic balances. By combining prepared copolymers with photothermal graphene oxide as a heat transducer, we demonstrated gradual solar control of the smart window in response to sunlight intensity in outdoor testing.
authors.affiliation: Department of Chemistry, Dong-A University , 37 Nakdong-Daero 550 beon-gil, Saha-gu, Busan, 49315, Republic of Korea.
authors.forename: Eunsu
authors.initials: E
authors.lastname: Lee
authors.affiliation: Department of Chemistry, Dong-A University , 37 Nakdong-Daero 550 beon-gil, Saha-gu, Busan, 49315, Republic of Korea.
authors.forename: Dowan
authors.initials: D
authors.lastname: Kim
authors.affiliation: Department of Chemistry, Dong-A University , 37 Nakdong-Daero 550 beon-gil, Saha-gu, Busan, 49315, Republic of Korea.
authors.forename: Jinhwan
authors.initials: J
authors.lastname: Yoon
keywords: gradient compositions; lower critical solution temperature; smart windows; stepwise solar control; thermotropic hydrogels