title: Photoinduced reversible change of fluid viscosity.
abstract: We report a reversible photoinduced fluid viscosity change. A small amount of a "photoswitchable" azobenzene-modified cationic surfactant (4-butylazobenzene-4'-(oxyethyl)trimethylammonium bromide, AZTMA) was added to a wormlike micellar solution of cetyltrimethylammonium bromide (CTAB) containing sodium salicylate (NaSal). The trans-AZTMA solution had a remarkably high viscosity as a result of the entangled network of wormlike micelles. UV light irradiation on the trans-AZTMA solution remarkably decreased the viscosity of the solution because the bulky structure of cis-AZTMA is likely to disrupt the network structure of wormlike micelles. This photoinduced viscosity change is perfectly reversible between the trans- and cis-AZTMA solutions.
authors.affiliation: Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan. hisakai@rs.noda.tus.ac.jp
authors.forename: Hideki
authors.initials: H
authors.lastname: Sakai
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Orihara
authors.forename: Hideki
authors.initials: H
authors.lastname: Kodashima
authors.forename: Atsutoshi
authors.initials: A
authors.lastname: Matsumura
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ohkubo
authors.forename: Koji
authors.initials: K
authors.lastname: Tsuchiya
authors.forename: Masahiko
authors.initials: M
authors.lastname: Abe