Hydration dynamics in aqueous Pluronic P123 solution: Concentration and temperature dependence

Area of Science:

• Polymer science
• Solution chemistry
• Physical chemistry

Background:

• Triblock copolymers like Pluronic P123 are crucial in various applications.
• Understanding their solution behavior, including phase transitions and water dynamics, is essential.

Purpose of the Study:

• To investigate concentration and temperature-dependent structural and dynamical changes in aqueous Pluronic P123 solutions.
• To characterize the dynamics of water molecules and polymer chains.

Main Methods:

• Dielectric relaxation spectroscopy (DRS) over a wide frequency range (0.2–50 GHz).
• Differential scanning calorimetry (DSC) to support DRS observations.

Main Results:

• Detection of both bulk-like and significantly slower water molecules (approx. 2x slower).
• Identification of a sol-gel phase transition around 15.0 wt.% at 293 K.
• Observation of extensive temperature-induced dehydration (>60%) of P123 molecules, with rates dependent on the medium's phase (sol or gel).
• A subnanosecond relaxation component (approx. 90 ps) attributed to polymer chain terminal group dynamics.

Conclusions:

• Pluronic P123 solutions exhibit complex water dynamics and distinct phase transition behavior.
• Temperature significantly influences polymer dehydration, with nonlinear patterns observed in both sol and gel phases.
• The study provides insights into the molecular-level interactions governing Pluronic P123 aqueous solutions.