Controlling the Structure of Supraballs by pH-Responsive Particle Assembly.
Supraballs of various sizes and compositions can be fabricated via drying of drops of aqueous colloidal dispersions on super-liquid-repellent surfaces with no chemical waste and energy consumption. A "supraball" is a particle composed of colloids. Many properties, such as mechanical strength and porosity, are determined by the ordering of a colloidal assembly. To tune such properties, a colloidal assembly needs to be controlled when supraballs are formed during drying. Here, we introduce a method to control a colloidal assembly of supraballs by adjusting the dispersity of the colloids. Supraballs are fabricated on superamphiphobic surfaces from colloidal aqueous dispersions of polystyrene microparticles carrying pH-responsive poly[2-(diethylamino)ethyl methacrylate]. Drying of dispersion drops at pH 3 on superamphiphobic surfaces leads to the formation of spherical supraballs with densely packed colloids. The pH 10 supraballs are more oblate and consist of more disordered colloids than the pH 3 supraballs, caused by particle aggregates with random sizes and shapes in the pH 10 dispersion. Thus, the shape, crystallinity, porosity, and mechanical properties could be controlled by pH, which allows broader uses of supraballs.
Department of Applied Chemistry, Faculty of Engineering, Osaka Institute of Technology , 5-16-1 Omiya, Asahi-ku, Osaka 535-8585, Japan.
Takafumi
T
Sekido
Physics at Interfaces, Max Planck Institute for Polymer Research , Ackermannweg 10, D-55128 Mainz, Germany.
Sanghyuk
0000-0002-6535-370X
S
Wooh
Physics at Interfaces, Max Planck Institute for Polymer Research , Ackermannweg 10, D-55128 Mainz, Germany.
Regina
R
Fuchs
Physics at Interfaces, Max Planck Institute for Polymer Research , Ackermannweg 10, D-55128 Mainz, Germany.
Michael
M
Kappl
Department of Applied Chemistry, Faculty of Engineering, Osaka Institute of Technology , 5-16-1 Omiya, Asahi-ku, Osaka 535-8585, Japan.
Yoshinobu
Y
Nakamura
Physics at Interfaces, Max Planck Institute for Polymer Research , Ackermannweg 10, D-55128 Mainz, Germany.
Hans-Jürgen
0000-0001-5391-2618
HJ
Butt
Department of Applied Chemistry, Faculty of Engineering, Osaka Institute of Technology , 5-16-1 Omiya, Asahi-ku, Osaka 535-8585, Japan.
Syuji
0000-0003-2562-9502
S
Fujii