Effect of Block\nCopolymer Concentration and Water–Ethanol\nRatio on Phase Transitions of Pluronics Using Molecular Dynamics Simulations

Pluronics,\nalso known as poly(ethylene oxide)–poly(propylene\noxide)–poly(ethylene oxide) (PEO–PPO–PEO) block\ncopolymers (BCP), are recognized for their ability to self-assemble\ninto diverse mesophases, making them valuable in designing materials\nwith tailored properties for applications in drug delivery and nanotechnology.\nAlthough the formation of these self-assembled structures is achieved\nby the widely utilized method of modulating the solvent–cosolvent\ncomposition, a comprehensive understanding of their underlying mechanism\nand phase transition behavior still remains elusive. Here, we used\ncoarse-grained molecular dynamics simulations to explore the self-assembly\nof different triblock copolymers in a water/ethanol mixture with different\ncompositions. The investigation includes an exploration of the impact\nof BCP concentration and the PPO/PEO block ratio on cosolvent-induced\nself-assembly. The outcomes unveil a diverse array of mesophases formed\nby BCP within the ternary BCP/water/ethanol mixture. We observed that\nthe cosolvent-induced morphological transitions are governed by the\nselective affinity of PPO and PEO blocks toward the solvent and cosolvent.\nIt also alters the local chemical environment and conformational changes\nin individual BCP chains. Additionally, we find that the influence\nof solvent–cosolvent composition is significant at low BCP\ncomposition, instigating an unimeric-to-micellar phase transition,\nwhile at high BCP composition, the PPO/PEO block ratio dominates the\neffect of solvent–cosolvent composition and determines the\nself-assembled morphology. Our results offer fundamental insights,\nserving as a guide to control the morphology of BCP self-assembly\nby fine-tuning the solvent–cosolvent ratio.