Effect of phosphate buffer on the micellisation process of Poloxamer 407: Microcalorimetry, acoustic spectroscopy and dynamic light scattering (DLS) studies

• Influence of inorganic salts on the micellisation of Poloxamer 407.
• Deeper understanding of the micellisation process by using different techniques.
• Anions act as “structure makers”, by straightening water–water interactions.
• Ions enhance the whole gain in entropy during micellisation.
• The change of the water molecules order is the real driving force of the process.

The influence of inorganic salts, commonly used as buffer system, on the micellisation of Poloxamer 407 was analyzed through the combination of three different analytical techniques, such as microcalorimetry, ultrasonic spectroscopy and dynamic light scattering.The general results are in agreement with the Hofmeister series behaviour confirming data found in the literature. However, the simultaneous use of different methodologies allowed a deeper understanding of the micellisation process clarifying the role of ions on the dynamic of the process itself. The self-aggregation phenomenon is mainly driven by the water–poloxamer and water–water interactions. Ions play a crucial role by modifying these interactions and consequently the general order of the systems, entropically promoting the micellisation process.

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