Open AccessReconfiguring Gaussian Curvature of Hydrogel Sheets with Photoswitchable Host–Guest Interactions
Author(s) -
Alexa S. Kuenstler,
Markus Lahikainen,
Hantao Zhou,
Wenwen Xu,
Arri Priimägi,
Ryan C. Hayward
Publication year - 2020
Publication title -
acs macro letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.966
H-Index - 92
ISSN - 2161-1653
DOI - 10.1021/acsmacrolett.0c00469
Subject(s) - azobenzene , swelling , isomerization , self healing hydrogels , soft robotics , materials science , curvature , morphing , photothermal effect , gaussian , chemical physics , nanotechnology , chemical engineering , photothermal therapy , computer science , composite material , polymer chemistry , polymer , chemistry , organic chemistry , computational chemistry , robot , artificial intelligence , geometry , mathematics , catalysis , engineering
Photoinduced shape morphing has implications in fields ranging from soft robotics to biomedical devices. Despite considerable effort in this area, it remains a challenge to design materials that can be both rapidly deployed and reconfigured into multiple different three-dimensional forms, particularly in aqueous environments. In this work, we present a simple method to program and rewrite spatial variations in swelling and, therefore, Gaussian curvature in thin sheets of hydrogels using photoswitchable supramolecular complexation of azobenzene pendent groups with dissolved α-cyclodextrin. We show that the extent of swelling can be programmed via the proportion of azobenzene isomers, with a 60% decrease in areal swelling from the all trans to the predominantly cis state near room temperature. The use of thin gel sheets provides fast response times in the range of a few tens of seconds, while the shape change is persistent in the absence of light thanks to the slow rate of thermal cis-trans isomerization. Finally, we demonstrate that a single gel sheet can be programmed with a first swelling pattern via spatially defined illumination with ultraviolet light, then erased with white light, and finally redeployed with a different swelling pattern.