pubs.rsc.org/en/content/articlelanding/2005/sm/b512610j

The SO₄²⁻-induced micellization of poly(ethylene glycol)-block-poly(4-vinylpyridinium) (PEG-b-P(4-VPH⁺)) in aqueous solution is studied by dynamic and static light scattering, and transmission electron microscopy. The SO₄²⁻ anions can act as cross-linkers of the P(4-VPH⁺) blocks through the electrostatic attraction between 4-VPH⁺ and SO₄²⁻ to induce the micellization of PEG-b-P(4-VPH⁺). The resultant hybrid micelles are spherical and consist of an ion-complex core of P(4-VPH⁺)/SO₄²⁻ and a water-soluble PEG corona and present a density gradient between the core and corona and the core has a higher density. The SO₄²⁻ concentrations can affect the structure of the core–corona hybrid micelles. The low SO₄²⁻ conentration leads to a loose core while the high SO₄²⁻ concentration leads to a compact core.