Self-Assembly and Gelation Behavior of Methacrylated PEO–PPO–PEO Triblock Copolymer Pluronic F127

Abstract

Methacrylated Pluronic triblock copolymers are widely used as photo-cross-linkable hydrogels, yet the effect of terminal methacrylation on self-assembly and thermoreversible gelation prior to cross-linking remains poorly understood. Here, we systematically investigate how the degree of methacrylation influences micellization, micelle packing, and gelation in Pluronic F127 using differential scanning calorimetry, rheology, synchrotron small-angle X-ray scattering (SAXS), in situ heating SAXS, and cryogenic transmission electron microscopy. Micellization thermodynamics are largely unaffected by methacrylation, with similar micellization enthalpies, temperatures, micelle core sizes, and aggregation numbers across all samples, confirming that micellization remains governed by PPO dehydration. In contrast, gelation is impacted. Increasing methacrylation shifts the gelation temperature to higher values, broadens the soft gel regime, and delays the emergence of long-range micellar order. SAXS and cryo-TEM reveal weakened intermicellar interactions, reduced corona interpenetration, and the formation of smaller, less ordered micellar domains with increasing methacrylation. Time-resolved SAXS further shows that methacrylation slows gelation kinetics under nonequilibrium heating conditions. Overall, terminal methacrylation primarily alters gelation through kinetic and structural effects rather than changes in micellization energetics. The resulting gel diagrams provide practical guidelines for designing methacrylated Pluronic hydrogels in applications requiring controlled gelation, including photo-cross-linking, additive manufacturing, drug delivery, and tissue engineering.