Photo-responsive traveling of small-particles modified with azobenzene groups as molecular motors in a liquid crystal

• Azobenzene(Azo) groups have modified micro-particles(MP) as molecular motors.
• The Azo-modified MPs (Azo/MPs) could be manipulated by light in a liquid crystal.
• The Azo/MP can be transported a few millimeters by scanning light in nematic phase.
• The motional behavior suggests to be induced by disorder of liquid crystals.
• The disorder could be induced by continuous trans-cis-trans isomerization of Azos.

Remote control of small objects by external stimuli has become a critical technology with applications in research fields such as biotechnology and industrial fabrication technology. In a nematic liquid crystal, 5CB, we have achieved remote control of the azobenzene-modified microparticles (Azo/MPs) by light stimuli. The light-driven Azo/MPs were prepared by modification of photo-responsive Azo groups as molecular motors. A couple of Azo/MPs could be transported a few millimeters for 160 s by scanning the sample stage in the irradiation region at 33 °C. As results from UV–visible extinction spectroscopy and from phase evaluation under irradiation, the motion behavior suggests to be correlated with generation of micro-sized disorganization regions like isotropic phase on the nematic phase of the 5CB. The disorganization region could be generated by photo-induced continuous trans-cis-trans isomerization of Azo groups under light irradiation.

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