Pluronic® P-123 (PEO-PPO-PEO)

Pluronic P-123 is a symmetrical triblock copolymer composed of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) arranged in an alternating linear structure, PEO-PPO-PEO. The distinctive feature of the PPO block is its hydrophobic nature at temperatures above 288 K and its solubility in water at temperatures below 288 K, leading to the formation of micelles consisting of PEO-PPO-PEO triblock copolymers. Some studies indicate that the hydrophobic core contains the PPO block, while a hydrophilic corona consists of the PEO block. In a 30wt% aqueous solution, Pluronic P123 adopts a cubic gel phase.

The nominal chemical formula of P123 is HO(CH₂CH₂O)₂₀(CH₂CH(CH₃)O)₇₀(CH₂CH₂O)₂₀H, corresponding to a molecular weight of approximately 5800 g/mol. Triblock copolymers based on PEO-PPO-PEO chains are commonly known as poloxamer.

Poloxamers exhibit behaviors akin to those of hydrocarbon surfactants and will form micelles when placed in a selective solvent such as water. They have the ability to form both spherical and cylindrical micelles.