We
report a visible light-responsive bilayer actuator driven by
the photothermal properties of a unique molecular photoswitch: donor–acceptor
Stenhouse adduct (DASA). We demonstrate a synthetic platform to chemically
conjugate DASA to a load-bearing poly(hexyl methacrylate) (PHMA) matrix
via Diels–Alder click chemistry that enables access to stimuli-responsive
materials on scale. By taking advantage of the negative photochromism
and switching kinetics of DASA, we can tune the thermal expansion
and actuation performance of DASA–PHMA under constant light
intensity. This extends the capabilities of currently available responsive
soft actuators for which mechanical response is determined exclusively
by light intensity and enables the use of abundant broadband light
sources to trigger tunable responses. We demonstrate actuation performance
using a visible light-powered cantilever capable of lifting weight
against gravity as well as a simple crawler. These results add a new
strategy to the toolbox of tunable photothermal actuation by using
the
molecular photoswitch DASA.
We
report the synthesis of diblock poly-amido-saccharides (PASs)
by sequential addition of variably protected glucose and galactose
monomers via living anionic ring-opening polymerization. Diblock polymers
with varied polymer length, hydrophobic to hydrophilic ratio, and
stereochemistry of hydrophilic component were synthesized, characterized
by NMR, IR, and GPC. These amphiphilic polymers self-assemble in water
to form nanoparticles as determined by DLS, SEM, and cryo-TEM. Amphiphilic
polymers with glucose-PAS hydrophobic and galactose-PAS hydrophilic
blocks and degree of polymerization of 100 (100-EtGlc1-OHGal3diblock PAS) form
spherical nanostructures and are non-cytotoxic.
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