A vast number of photo-switchable molecules have been discovered and thoroughly studied. The excitation caused by UV light in azobenzene weakens the central azo-double bond enabling the conversion of cis/trans isomers. For applications such as artificial muscles or photo-activated pumps, one challenge that has plagued success in this area is locking or over cross-linking of the structure, which forbids isomerization in azobenzene at the macroscale or under cross-linking where the materials fall apart. This is especially true for silicon-based hybrid materials. Our group has successfully synthesized a silsesquioxane based network polymer capable of executing isomerization at the macroscale through curving in films and shrinking/swelling in gels. Our films can perform up to five times of self-flipping and gel systems perform size change of up to 17% under irradiation cycling between UV and visible light irradiation. Both systems stay active after dry out/reswell.

Reversible solvent loading and unloading in photo-actuatable silsesquioxane-based network gels

ACS Fall 2020 Virtual Meeting

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