Chemistry Colloquium: "Controlling Polymers with Light"

Dr. Si Wu, Department of Polymer Science and Engineering, University of Science and Technology of China
Host: Dr. Jie He

In this talk, I will present synthesis of photoresponsive polymers and controlling their properties and functions with light. My talk contains three parts. In the first part, I will show you that light can switch the glass transition temperature (Tg) of azobenzene-containing polymers (azopolymers) and induce reversible solid-to-liquid transitions of the polymers. [1,2] The azobenzene groups in the polymers exhibit reversible cis-trans photoisomerization. Trans azopolymers are solids with Tg above room temperature, whereas cis azopolymers are liquids with Tg below room temperature. Because of the photoinduced solid-to-liquid transitions of these polymers, light can repeatedly heal cracks in azopolymers, reduce the surface roughness of azopolymer films, and control the adhesion of azopolymers for transfer printing. In the second part, I will introduce red-light-responsive Ru-containing polymers and their applications in phototherapy and reconfigurable materials. [3-5] We synthesized Ru-containing block copolymers (BCPs). The Ru moieties act as light-cleavable groups , singlet oxygen sensitizers and anticancer agents. The BCPs assembled into micelles, vesicles, large compound micelles and other nanostructures. The BCP assemblies can be taken up by cancer cells. Red light can pass through tissue and activate the Ru-containing BCP assemblies. The photoactivated Ru-containing BCP assemblies can inhibit the growth of cancer cells. Photoresponsive Ru complexes were also used to construct reconfigurable surfaces . In the third part, I will present near-infrared light induced release and ligation of polymers assisted by upconverting nanoparticles (UCNPs). [6-8] UCNPs convert NIR light to UV or visible light that can trigger photoreactions Thus, near-infrared light-responsive materials can be fabricated using UCNPs.

References
[1] H. Zhou, C. Xue, P. Weis, Y. Suzuki, S. Huang, K. Koynov, G. K. Auernhammer, R. Berger, H.-J. Butt, S. Wu, Nature Chemistry 2017, 9, 145
[2] W.-C. Xu, S. Sun, S. Wu, Angew. Chem. Int. Ed. 2019, in press
[3] W. Sun, S. Li, B. Haupler, J. Liu, S. Jin, W. Steffen, U. S. Schubert, H. J. Butt, X. J. Liang, S. Wu, Adv. Mater. 2017, 29, 1603702
[4] W. Sun, Y. Wen, R. Thiramanas, M. J. Chen, J. X. Han, N. Q. Gong, M. Wagner, S. Jiang, M. S. Meijer, S. Bonnet, H. J. Butt, V. Mailander, X. J. Liang, S. Wu, Adv. Funct. Mater. 2018, 28, 1804227
[5] C. M. Xie, W. Sun, H. Lu, A. Kretzschmann, J. H. Liu, M. Wagner, H. J. Butt, X. Deng, S. Wu, Nature Communications 2018, 9, 3842
[6] S. Wu, H.-J. Butt, Adv. Mater. 2016, 28, 1208
[7] P. Lederhose, Z. Chen, R. Mueller, J. P. Blinco, S. Wu, C. Barner-Kowollik, Angew. Chem. Int. Ed. 2016, 55, 12195
[8] Z. Chen, S. He, H. J. Butt, S. Wu, Adv. Mater. 2015, 27, 2203

Refreshments will be served at 10:15am. All are welcome.