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Download fileInsight into a Fast-Phototuning Azobenzene Switch for Sustainably Tailoring the Foam Stability
journal contribution
posted on 28.03.2017, 00:00 authored by Shaoyu Chen, Yanyan Zhang, Kunlin Chen, Yunjie Yin, Chaoxia WangA photoresponsive
surfactant of 4-octoxy-4′-[(trimethylamino)ethoxy]azobenzene
(OTAEAzo) has been synthesized for developing a fast-phototuning foam
switch based on its high sensitivity, reversibility, and fatigue resistance
of the photoisomerization capability. Ultraviolet (UV)-light irradiation
for 1 s enabled conversion from the trans isomer to the cis configuration,
while exposure to visible (Vis)-light for 3 min induced a cis-to-trans transformation, which maintains
an excellent cycling stability for 20 cycles of photoisomerization.
The photoisomerization speed depended on the concentration of OTAEAzo,
and a lower concentration facilitated a faster photoisomerization
process. Because of the low critical micelle concentration (CMC),
OTAEAzo with a small dosage of 0.2 g·L–1 showed
foamability, which accelerated the photoisomerization speed, enabling
it to become a highly efficient switch. The surface activities of trans-OTAEAzo presented distinct differences from those
of cis-OTAEAzo, resulting in the foam stabilization
effects of trans-OTAEAzo (t1/2 = 2.58 min) and the destabilization effects of cis-OTAEAzo (t1/2 = 0.38 min).
Moreover, the foam properties varied slightly in the phototuning cycles.
OTAEAzo with low CMC presents high sensitivity and reversible photoisomerization
capability, providing an environmental and sustainable approach for
tailoring the foam stability.