From Event: SPIE Organic Photonics + Electronics, 2018
The development of polymers with switchable glass transition temperatures (Tg) can address scientific challenges, including the healing of cracks in high-Tg polymers and the processing of hard polymers at room temperature without using plasticizing solvents. In this talk, I will show you that light can switch the Tg of azobenzene-containing polymers (azopolymers) and induce reversible solid-to-liquid transitions of the polymers (Nature Chemistry 2017, 9, 145). The azobenzene groups in the polymers exhibit reversible cis-trans photoisomerization. Trans azopolymers are solids with Tg above room temperature, while cis azopolymers are liquids with Tg below room temperature. Because of the photoinduced solid-to-liquid transitions of these polymers, light can reduce the surface roughness of azopolymer films, repeatedly heal cracks in azopolymers, and control the adhesion of azopolymers for transfer printing. The photoswitching of Tg provides a new strategy for designing healable polymers with high Tg and allow for control over the mechanical properties of polymers with high spatiotemporal resolution.
Si Wu, "Photoswitching of Tg of azopolymers induces reversible solid-to-liquid transitions (Conference Presentation)," Proc. SPIE 10740, Molecular Machines, 1074009 (Presented at SPIE Organic Photonics + Electronics: August 23, 2018; Published: 18 September 2018); https://doi.org/10.1117/12.2319609.5836543625001.
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