Flavylium-Supported Poly(<i>N</i>‑isopropylacrylamide):
A Class of Multistimuli Responsive Polymer
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Abstract
A new
multistimuli responsive polymer was prepared by means of
the free-radical copolymerization of <i>N</i>-isopropylacrylamide
and a vinyl flavylium derivative. The polymer shows response to temperature
(conferred by the <i>N</i>-isopropylacrylamide units) and
pH and light stimuli (conferred by the flavylium moieties). The polymer
follows the typical pH dependent network of chemical reactions of
flavylium compounds in water that was studied by means of UV–vis
spectroscopy and stationary fluorescence emission. Regarding the temperature
response, the presence of the flavylium cation in the polymeric chains
reduces the LCST, and it is possible to take advantage of this effect
to photo-collapse partially the polymer by irradiating the system
in defined ranges of pH and temperature