Speaker
Description
Light-induced mechanical actuation in materials offers a powerful route to remote, reversible control of shape and function, supporting advances in soft robotics, adaptive optics, and smart surfaces. The development of artificial molecular machines, including light-driven rotary motors, was recognized by the 2016 Nobel Prize in Chemistry for “the design and synthesis of molecular machines”, underscoring the significance of gaining control of light-reversible motion at the molecular scale. Photo-mechanical materials, which hold the intrinsic ability to undergo reversible mechanical deformation in response to light, can be added as a thin active layer into other flexible or mechanically strong materials, inducing substantial bending or actuation of the entire structure, even when the support is significantly thicker than the active photo-mechanical layer itself. Among these light-powered ‘artificial muscles’, azobenzene-containing systems have emerged as a leading platform, where light-induced cis–trans molecular geometric isomerization of the azo dye molecules can drive macroscopic shape changes and control large-scale mechanical properties.
The efficiency of the photo-mechanical effect of thin films of three azobenzene-based polymers, PDR1A, PDR13A and PMMA-co-PDR1A, was determined using a cantilever-based sensor. The polymers were coated onto silicon and mica cantilevers, and the resulting cantilever bending under irradiation with visible light was measured to estimate changes in surface stress, photo-mechanical energy transduction, and overall efficiency. The photo-mechanical response was shown to be robust, repeatable, and quantifiable for all the polymers studied, even when the active polymer layer was much thinner than the cantilever substrate. For 35-µm-thick mica cantilevers coated with PDR1A, photo-isomerization induced rapid and significant cantilever bending in the range of 100s of µm, corresponding to surface stress changes in the range of N/m. These results demonstrate the ability of thin azobenzene polymer films to function as strong, light-driven ‘artificial muscles’ in larger mechanical systems, and demonstrate the cantilever sensor platform as a promising tool for the quantitative characterization of photo-mechanical effects in azobenzene-based polymers.
| Keyword-1 | photo-mechanics |
|---|---|
| Keyword-2 | molecular machines |
| Keyword-3 | azo polymers |