am9b17271_si_002.mp4 (17.55 MB)
Rapid, Localized, and Athermal Shape Memory Performance Triggered by Photoswitchable Glass Transition Temperature
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posted on 2019-11-26, 14:48 authored by Xiao Zhang, Chongyu Zhu, Bo Xu, Lang Qin, Jia Wei, Yanlei YuShape memory polymers that undergo shape recovery at
room temperature
(RT) are desirable for their potential in vivo applications, yet challenging.
Herein, light-triggered athermal shape memory effect of azopolymer
networks is reported by photoswitching the glass transition temperature
(Tg) rather than external heating. Thanks
to the switchable Tg of azopolymer induced
by reversible trans–cis isomerization, the
entropic energy is trapped in low Tg state
(cis-form Tg < RT)
to deform into a temporary shape and fixed in high Tg state (trans-form Tg > RT). Upon exposure to UV light, the reduced low Tg allows release of the entropic energy, realizing
athermal shape recovery of the permanent shape. By exploring the shape
memory performance, we demonstrate diverse light-induced rapid shape
recovery from temporary shape to original shape. Because of the instant,
precise, and spatiotemporal manipulation of light, programmable shape
recovery of surface topography is further extended. We anticipate
that this strategy will provide tremendous opportunities for future
precise medicine devices and soft robotics.