Hierarchically organized micellization of thermoresponsive rod-coil copolymers based on poly[oligo(ethylene glycol) methacrylate] and poly(ε-caprolactone)

Abstract

A series of amphiphilic triblock copolymers, poly[oligo(ethylene glycol) methacrylate]x-block-poly(ε-caprolactone)-block-poly[oligo(ethylene glycol) methacrylate]x, POEGMACo(x), were synthesized. Formation of hydrophobic domains as cores of the micelles was studied by fluorescence spectroscopy. The critical micelle concentrations in aqueous solution were found to be in the range of circa 10⁻⁶ M. A novel methodology by modulated temperature differential scanning calorimetry was developed to determine critical micelle temperature. A significant concentration dependence of cmt was found. Dynamic light scattering measurements showed a bidispersed size distribution. The micelles showed reversible dispersion/aggregation in response to temperature cycles with lower critical solution temperature between 75 and 85 °C. The interplay of the two hydrophobic and one thermoresponsive macromolecular chains offers the chance to more complex morphologies.