Star-shaped polymeric
materials provide very high efficiency toward
various engineering and biomedical applications. Due to the absence
of straightforward and versatile synthetic protocols, the synthesis
of sequence-defined star-shaped (co)polymers has remained a major
challenge. Here, a facile approach is developed that allows synthesis
of a series of unprecedented discrete, multifunctional four-, six-,
and eight-arm star-shaped complex macromolecular architectures based
on a well-defined triple (thermo/pH/light)-stimuli-responsive poly(N-isopropylacrylamide)-block-poly(methacrylic
acid)-umbelliferone (PNIPAM-b-PMAA)
n
-UMB diblock copolymer, based on temperature responsive PNIPAM
segment, pH-responsive PMAA segment, and photoresponsive UMB end groups.
Thus, developed star-shaped copolymers self-assemble in water to form
spherical nanoaggregates of diameter 90 ± 20 nm, as measured
by FESEM. The star-shaped copolymer’s response to external
stimuli has been assessed against changes in temperature, pH, and
light irradiation. The star-shaped copolymer was employed as a nanocarrier
for pH responsive release of an anticancer drug, doxorubicin. This
study opens up new avenues for efficient star-shaped macromolecular
architecture construction for engineering and biomedical applications.