This study demonstrates the superior performance of cellulose nanofibril (CNF)-reinforced microcapsules for phase change material (PCM) encapsulation. Compared to conventional polyurethane encapsulation, CNF incorporation yields significant improvements in both structural and thermal properties while enhancing sustainability.

The CNF-modified microcapsules exhibit thick shells (530 nm maximum) with substantially improved mechanical strength, enabling better resistance to PCM volume changes during phase transitions. This structural enhancement leads to 78% encapsulation efficiency – an 11% increase over method without CNF – and to improved thermal stability due to the shift in onset decomposition temperatures and a more efficient protection of the encapsulated OD from elution in the organic solvent. The uniform CNF distribution creates a robust fibrous network that maintains capsule integrity through repeated thermal cycles.

CNF modification eliminates synthetic surfactants through its natural emulsifying properties while reducing chemical crosslinker requirements. The renewable nature of CNF makes this approach particularly attractive for sustainable energy storage solutions.

These advancements position CNF-enhanced microcapsules as ideal for demanding applications in building materials, thermal textiles, and electronic cooling systems where conventional encapsulation falls short. The combination of improved durability, thermal regulation, and eco-friendly credentials represents a significant advancement in PCM technology. Future work will focus on optimizing CNF surface modifications for specific application requirements while maintaining the demonstrated performance benefits. This research establishes CNF as a transformative additive for next-generation thermal energy storage systems.