Expanding our understanding of a particular process, material, or mechanism usually requires taking a close look at what is going on. Researchers in Japan have now observed the nanoscale behavior of azo-polymer films when triggered with laser light.
High-speed atomic force microscopy combined with a laser irradiation system for the in-situ real-time observation of azo-polymer deformation process. Image Credit: Osaka University
In a study published in Nano Letters, researchers from Osaka University employed tip-scan high-speed atomic force microscopy (HS-AFM) in conjunction with an optical microscope to generate movies of polymer films changing.
Azo-polymers are materials that change when exposed to light since they are photoactive materials. In particular, light modifies their chemical composition, changing the films’ surface. This makes them intriguing for uses like light-triggered motion and optical data storage.
In situ measurement refers to the ability to start these changes using a focused laser light while taking images.
It is usual to investigate changes in polymer films by subjecting them to a treatment, such as irradiating with light and then making measurements or observations afterward. However, this provides limited information. Using an HS-AFM setup including an inverted optical microscope with a laser, allowed us to trigger changes in azo-polymer films while observing them in real time with high spatiotemporal resolution.
Keishi Yang, Study Lead Author and Graduate Student, Osaka University
The HS-AFM measurements allowed researchers to trace the dynamic changes in the surfaces of polymer films in two-frame-per-second movies. It was also discovered that the direction of the polarized light employed affected the final surface design.
More research employing the in situ technique is anticipated to result in an in-depth understanding of the process of light-driven azo-polymer deformation, enabling the full potential of these materials to be realized.
We have demonstrated our technique for observing polymer film deformation. However, in doing so, we have shown the potential of combining tip-scan HS-AFM and a laser source for use across materials science and physical chemistry.
Takayuki Umakoshi, Study Senior Author and Associate Professor, Osaka University
Materials and processes that respond to light play a significant role in numerous areas of chemistry and biology, including sensing, imaging, and nanomedicine. The in situ approach offers the chance to improve understanding and optimize potential and is expected to be used in a variety of optical systems.
Journal Reference:
Yang, K., et. al. (2024) In Situ Real-Time Observation of Photoinduced Nanoscale Azo-Polymer Motions Using High-Speed Atomic Force Microscopy Combined with an Inverted Optical Microscope. Nano Letters. doi:10.1021/acs.nanolett.3c04877.