Docosane-Organosilica Microcapsules for Structural Composites with Thermal Energy Storage/Release Capability

Area of Science:

• Materials Science
• Energy Storage
• Composite Materials

Background:

• Organic phase change materials (PCMs) are crucial for managing intermittent energy sources like solar thermal energy.
• Developing effective thermal energy storage (TES) solutions is vital for renewable energy integration.
• Structural composites offer a dual function of load-bearing and energy storage.

Purpose of the Study:

• To encapsulate docosane within organosilica shells for thermal energy storage.
• To create multifunctional structural composites by dispersing these microcapsules in epoxy/carbon laminates.
• To investigate the thermal and mechanical properties of the resulting composite materials.

Main Methods:

• Microencapsulation of docosane using methyltriethoxysilane (MTES) via hydrolysis-condensation in an oil-in-water emulsion.
• Characterization using X-ray diffraction (XRD), ¹³C solid-state nuclear magnetic resonance (NMR), and differential scanning calorimetry (DSC).
• Dispersion of microcapsules in epoxy and epoxy/carbon laminates, followed by mechanical testing (three-point bending, dynamic mechanical analysis) and thermal analysis.

Main Results:

• XRD and NMR confirmed successful encapsulation and revealed confinement effects on docosane's crystalline structure and chain mobility.
• DSC determined a phase change enthalpy up to 143 J/g for microcapsules, with encapsulation increasing docosane's phase change activation energy.
• Mechanical tests showed a decrease in properties due to microcapsule agglomeration and poor adhesion, though TES functionality was confirmed.

Conclusions:

• Organosilica microencapsulation effectively enables docosane for thermal energy storage applications within structural composites.
• While TES properties were achieved, optimizing microcapsule dispersion and adhesion is critical for maintaining mechanical integrity.
• The developed composites show promise for integrated thermal management in structural applications.