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

## TL;DR

This study explores how methacrylation affects the self-assembly and gelation of Pluronic F127, a common hydrogel material, using various analytical techniques.

## Contribution

The study reveals that methacrylation alters gelation behavior through kinetic and structural effects, not micellization energetics.

## Key findings

- Micellization thermodynamics remain unaffected by methacrylation.
- Gelation is delayed and softened with increasing methacrylation.
- Methacrylation reduces micellar order and intermicellar interactions.

## 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.