Effect of pH on the micellar morphology of semicrystalline PCL-b-PEO block copolymers in aqueous solution

摘要

The effect of pH on the micellar morphology of a semicrystalline poly(ε-caprolactone)-block-poly(ethylene oxide) block copolymer (PCL _(66)-b-PEO _(44)) in aqueous solution is investigated. Spherical micelles are formed in neutral and acidic solutions. However, addition of alkali to the neutral micellar solution triggers a sphere-to-cylinder transformation of the micellar morphology. The micelles are stable in both neutral and acidic solutions, but the size of the micelles becomes gradually larger in the alkali solution. This phenomenon is interpreted in terms of the effect of pH value on the reduced tethering density of the corona in the semicrystalline micelles.