Specific heat at the micellization and phase transitions in a triblock copolymer-water system

The triblock copolymer (``unimer'') of PPO-PEO-PPO (commercially known as 17R4) has hydrophobic ends and a hydrophilic center. When placed in water, a network of unimers can self-assemble at higher concentrations or temperatures to form micelles of different geometries. We have measured the micellization line marking the transition from only unimers in solution to some micelles. There is also a one- to two-phase transition at higher temperatures that is an Ising-like, LCST critical point. Specific heat measurements from our adiabatic calorimeter provide the enthalpy, entropy and free energy of micellization along the micellization line at different prepared compositions.