Pluronic P123 is a symmetric triblock copolymer comprising poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) in an alternating linear fashion, PEO-PPO-PEO.

Triblock copolymers based on PEO-PPO-PEO chains are known generically as poloxamer.

Poloxamers have behaviors similar to those of hydrocarbon surfactants, and will form micelles when placed in a selective solvent such as water.

They can form both spherical and cylindrical micelles [1] P123 has been used in the synthesis of mesoporous materials including FDU-14.

[2] Dissolved P-123 forms micelles that are used as the backbone to make structured mesoporous materials such as SBA-15.