(360ak) Insights into the Phase Diagram of Pluronic L64 Using Coarse-Grained Molecular Dynamics Simulations

We investigate the concentration dependent phase diagram of pluronic L64 in aqueous media at 300 K and 320 K using coarse grained (CG) molecular dynamics (MD) simulations. The CG model is derived by adapting the Martini model for non-bonded interactions along with the Boltzmann Inversion (BI) of bonded interactions from all atom (AA) simulations. Our derived CG model successfully captures the experimentally observed micellar, hexagonal and 2D phases. The end-to-end distance reveals the configurational transition from open-chain to folded-chain structure from micellar phase to lamellar phase, increasing the orientational order. Increase in temperature leads to expulsion of water molecules from L64 moiety suggesting increase in L64 hydrophobicity. The thermodynamic analysis using two phase thermodynamics (2PT) method suggests the entropy of the system decreases with increase in L64 concentration and the decrease in free energy (F) with temperature is mainly driven by entropic factor (-TS). Further, the increase in aggregation number at lower concentration and self-assembly at very high concentration is energetically driven whereas the micellar to lamellar transition is entropically driven. Our model provides the molecular insights into L64 phase transitions which can be further explored to design functionality based supra-structures for drug delivery and tissue engineering applications.