Confined self-assembly of block copolymers
(BCPs) is effective
to manipulate various shapes of particles. In emulsion confined self-assembly,
reversibly light-trigged switchable BCP particles are extremely expected,
yet rarely reported. Herein, a novel strategy is developed to realize
reversibly light-responsive shape-transformation of BCP particles
by constructing functional surfactants with light-active azobenzene
(azo) groups in the confined self-assembly of BCPs within emulsion
droplet. Ultraviolet and visible lights can reversibly modulate the
amphiphilicity and interfacial affinity of the surfactants to different
blocks, triggering the reversible microphase structure transformation
of BCP particles with high temporal-spatial resolution. We can realize
shape and morphological transitions of BCP particles from onion-shaped
spherical particles to striped ellipsoids and, ultimately, to inverse
onion-like particles by ultraviolet irradiation. More importantly,
this shape transformation is reversible by the irradiation of visible
light, attributed to the reversible trans–cis isomerization of azo groups. We also demonstrate that
the light-triggered shape transformation of BCP particles can be employed
in a controllable drug release through a noncontacted and programmed
manner, showing promising potential in clinic and biomedicine.