Presenter Profile

Professor Kiyoshi Kanie Kiyoshi Kanie is a Professor in International Center for Synchrotron Radiation Innovation Smart at Tohoku University in Sendai (Concurrent post: Institute of Multidisciplinary Research for Advanced Materials). He received his PhD from Kyoto University in 2000. He held research associate positions at the University of Tokyo and Tohoku University before being appointed an Associate Professor at Tohoku University in 2008 and a Full Professor in 2019. His research interests encompass, the design and synthesis of functional materials, liquid phase synthesis of functional inorganic nanoparticles with controlled size and shape and the development of organic-inorganic hybrid materials with dynamic functions. He was the recipient of the Science Award of the division of colloid and curface chemistry of the Chemical Society of Japan in 2010 and received the Japan Institute of Metals and Materials meritorious award in 2014.

TALK TITLE
Dynamic Control of Magnetic Nanoparticle Arrays by Surface Modification with Liquid-Crystalline Dendron

KEYWORDS
Nanoparticle, Self-organization, Liquid Crystal

ABSTRACT
Magnetic nanoparticles (NPs) exhibit unique magnetic properties depending on their interparticle magnetic interactions. Since the interactions mainly depend on their interparticle distance, dynamic control of NP arrays is expected to allow flexible control of their magnetic properties. However, control of the magnetic NP arrays is still a challenging issue because of strong magnetic attraction among magnetic NPs which causes aggregations. Our previous study demonstrated that surface modification of NPs with liquid-crystalline (LC) dendron is a powerful technique to control the NPs array dynamically due to thermal phase transition.1,2) Since the resulting dendrimers form sparse arrays, suppression of magnetic attraction among NPs is also expected by dendron modification. In this study, we have developed LC dendron-modifiedFe3O4 NPs to control magnetic NP-based array (Fig. 1).

Fig. 2 shows TEM images of Fe3O4 NPs before and after dendron modification. The particle diameter was calculated to be 6.8 ± 0.6 nm with no change in their size and shape during the reaction. On the other hand, the interparticle distance increased to 12.9 ± 1.0 nm from 8.7 ± 1.0 nm and well-ordered 2D hexagonal array was observed after dendron modification. It indicated that the self-assembling property of LC dendron was successfully introduced into Fe3O4 NPs. In addition, structural analysis by grazing incidence small angle X-ray scattering revealed that the array structures changed dynamically due to thermal phase transition. These results demonstrated that LC dendron modification enables us to control magnetic NP-based array. The self-assembling behavior of dendron-modified Fe3O4 NPs will be discussed.

1) K. Kanie, M. Matsubara, X. Zheng, F. Liu, G. Ungar, H. Nakamura, A. Muramatsu, J. Am. Chem. Soc., 134, 808 (2012).

2) M. Matsubara, W. Stevenson, J. Yabuki, X. Zeng, H. Dong, A. Muramatsu, G. Ungar, K. Kanie, Chem, 2, 860-876 (2017).