Self-assembly of poly(caprolactone-b-ethylene oxide-b-caprolactone) via a microphase inversion in water

Triblock copolymer poly(caprolactone-b-ethylene oxide-b-caprolactone) (PCL-PEO-PCL) could self-assemble into narrowly distributed flowerlike "core-shell" micelres when its tetrahydrofuran solution was added dropwise into an excess of water. The core was formed via the aggregation of insoluble hydrophobic PCL blocks, while the shell was made of many hydrophilic PEO loops. The formation and stabilization of such micelles were examined bl; a combination of static and dynamic laser light scattering. The average hydrodynamic size decreased as the dispersion temperature increased, but there was no change in the average radius of gyration, indicating that the temperature dependence of(Rh) during heating or cooling was attributed to the conformation change of the PEO block. The composition dependent study revealed that using two short PCL blocks and a long PEO block unexpectedly lead to smaller micelles. The study of their biodegradation in the presence of enzyme Lipase PS shows possible biomedical applications of such formed polymeric micelles.