Journal of Physical Chemistry B 2008-05-22

Thermoresponsive complex amphiphilic block copolymer micelles investigated by laser light scattering.

Fang Zhao, Dinghai Xie, Guangzhao Zhang, Stergios Pispas

Index: J. Phys. Chem. B 112(20) , 6358-62, (2008)

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Abstract

Poly(isoprene)-block-poly(ethylene oxide) (PI-b-PEO) diblock copolymers form micelles in water. The introduction of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (PEO-b-PPO-b-PEO) triblock copolymer leads to the formation of mixed micelles through hydrophobic interaction. The dimension of the mixed micelles varies with the weight ratio (r) of PEO-b-PPO-b-PEO to PI-b-PEO. By use of laser light scattering, we have investigated the temperature dependence of the structural evolution of the micelles at different r. At r<10, the size of the mixed micelles decreases with temperature. At r>10, due to the excessive PEO-b-PPO-b-PEO chains in solution, as temperature increases, the mixed micelles aggregate into larger micelle clusters.