Janus polymerization combines cationic and
anionic polymerizations into the two ends of a single growing
chain and presents a novel pathway to produce topologically
defined polymers. In this contribution, we report a one-step
synthesis of 3-miktoarm star terpolymers of poly(ethylene
glycol)-star-poly(ε-caprolactone)-star-poly(ε-caprolactone-cotetrahydrofuran)
(PEG-star-PCL-star-P(CL-co-THF)) via
Janus polymerization using lutetium triflates (Lu(OTf)3)
and methoxypoly(ethylene glycol) epoxy (mPEG-EO) as
catalyst and macroinitiator, respectively. Self-assembly
of PEG-star-PCL-star-P(CL-co-THF) into vesicles in aqueous
solution depends on the ratio of hydrophilic and hydrophobic
block of the terpolymers. Coassembly of the terpolymer with a
PCL homopolymer (MW = 3000), on the other hand, increases shell thickness and vesicle diameter. Furthermore, nanorods
and needle-shaped aggregates featuring high aspect ratios are obtained upon self-assembly at an interface. This unique behavior
can be attributed to crystallization of the PCL segments. Based on the biocompatible and biodegradable nature of the
constituting segments, the herein described 3-miktoarm star terpolymers might be promising materials for drug/gene delivery or
as bionanoreactors, especially as wall thickness and stiffness of the structures observed can be tuned. With that control over
(nano)local permeability might be feasible.