Polymer particles showing light-induced shape change

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K05999
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Polymer/Textile materials
• Research Institution: Ehime University
• Principal Investigator: Itoh Tomomichi 愛媛大学, 理工学研究科(工学系), 講師 (40363254)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 高分子構造・物性 / 高分子微粒子 / 光操作

Outline of Final Research Achievements

In this study, we developed azobenzene polymer particles showing several light-induced shape changes. Conventional azobenzene particles require exposure to polarized white or blue light on a substrate for shape elongation. First, the dispersion polymerization of an azobenzene monomer afforded unique oval or short cylindrical shapes with controlled sizes and narrow size distributions. Then, polarized optical microscopic observations and wide-angle X-ray diffraction measurements suggest that the azobenzene moiety formed a uniaxially-orientated smectic-layered structure in the particles. Finally, the particle shape was altered by the trans-cis photoisomerization of azobenzene. Interestingly, their shape anisotropy increased by ultraviolet and white-light irradiation. The particle shape was changed in a dispersed medium by unpolarized light. Consequently, the combination of a light source and site varied the light-induced shape changes of the azobenzene particles.

Free Research Field

高分子化学

Academic Significance and Societal Importance of the Research Achievements

微粒子の光形状変化は、条件が温和で操作性に優れるため、バイオマテリアル等への応用が期待できる。従来法では固定した微粒子に異方的な外場を与えることで形状を変化させる必要があったが、本研究による微粒子は異方場を微粒子内に構築しており、照射する外場が等方的な点が学術的に大きく異なる。これにより微粒子を固定する必要がなくなったため、細胞内のような不安定な足場での形状変化を可能にした点で、社会的意義が大きい。