Thermoresponsiveness of hybrid micelles from poly(ethylene glycol)-block-poly(4-vinylpyridium) cations annul SO42- anions in aqueous solutions

The SP42--induced micellization of poly(ethylene glycol)-block-poly(4-vinylpyridium) (PEG(110)-b-P(4-VPH+)(35)) and the thermoresponsiveness of these hybrid micelles are studied by dynamic and static light scattering. When the concentration of H2SO4 is high enough, PEG(110)-b-P(4-VPH+)(35) forms stable hybrid micelles with an ionic core of P(4-VPH+)(35)/SO42- and a PEG corona at 25 degrees C. The formation of the hybrid micelles is reversible. A thermodynamic equilibrium exists between the hybrid micelles and PEG(110)-b-P(4-VPH+)(35) unimers. The shifts of the equilibrium are mainly attributed to the variation of the electrostatic energy and entropic energy of the system. Therefore, the temperature can determine the states of the equilibrium, which means that the dissociation or the formation of the hybrid micelles can be triggered by just varying the temperature.