title: Thermoreversible crystallization of charged colloids due to adsorption/desorption of ionic surfactants.
abstract: We report that charged colloids exhibit thermoreversible crystallization via the adsorption of ionic surfactants onto particle surfaces. Due to the temperature dependence of the adsorption quantity, the colloids crystallized upon cooling and melted upon heating. To clarify the influences of surfactant adsorption on the crystallization, polystyrene (PS) particles dispersed in ethylene glycol (EG)/water mixtures were employed, enabling continuous tuning of the adsorption quantity by changing the EG concentration. The thermoreversible crystallization/melting behavior was found to be mainly attributable to changes in the ionic strength of the medium resulting from variation in the concentration of the non-adsorbed ionic surfactant molecules with temperature. We expect that the present findings will be useful for fine control of colloidal crystallization and the further study of colloidal crystallization in low permittivity media.
authors.affiliation: Faculty of Pharmaceutical Sciences, Graduate School of Nagoya City University, 3-1 Tanabe, Mizuho, Nagoya City, Aichi 467-8603, Japan. Electronic address: p112732@phar.nagoya-cu.ac.jp.
authors.forename: Ai
authors.initials: A
authors.lastname: Murakado
authors.affiliation: Faculty of Pharmaceutical Sciences, Graduate School of Nagoya City University, 3-1 Tanabe, Mizuho, Nagoya City, Aichi 467-8603, Japan. Electronic address: toyotama@phar.nagoya-cu.ac.jp.
authors.forename: Akiko
authors.initials: A
authors.lastname: Toyotama
authors.affiliation: Faculty of Pharmaceutical Sciences, Graduate School of Nagoya City University, 3-1 Tanabe, Mizuho, Nagoya City, Aichi 467-8603, Japan. Electronic address: masamonte101@yahoo.co.jp.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Yamamoto
authors.affiliation: Faculty of Pharmaceutical Sciences, Graduate School of Nagoya City University, 3-1 Tanabe, Mizuho, Nagoya City, Aichi 467-8603, Japan. Electronic address: ryota6677@hotmail.com.
authors.forename: Ryota
authors.initials: R
authors.lastname: Nagano
authors.affiliation: Faculty of Pharmaceutical Sciences, Graduate School of Nagoya City University, 3-1 Tanabe, Mizuho, Nagoya City, Aichi 467-8603, Japan. Electronic address: okuzono@phar.nagoya-cu.ac.jp.
authors.forename: Tohru
authors.initials: T
authors.lastname: Okuzono
authors.affiliation: Faculty of Pharmaceutical Sciences, Graduate School of Nagoya City University, 3-1 Tanabe, Mizuho, Nagoya City, Aichi 467-8603, Japan. Electronic address: yamanaka@phar.nagoya-cu.ac.jp.
authors.forename: Junpei
authors.initials: J
authors.lastname: Yamanaka
mesh_terms: D003102:Colloids; D019855:Ethylene Glycol / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D003102:Colloids; D013501:Surface-Active Agents; D014867:Water; D019855:Ethylene Glycol
keywords: Charged colloid; Colloidal crystal; Controlled crystallization; Ethylene glycol; Ionic surfactant