Efficient and Secure Encapsulation of a Natural Phase Change Material in Nanofibers Using Coaxial Electrospinning for Sustainable Thermal Energy Storage

Abstract

In this study, we present an ecofriendly technique for encapsulating lauric acid (LA), a natural phase change material, within polystyrene (PS) nanofibers through coaxial electrospinning. The resulting LAPS core–sheath nanofibers exhibited a melting enthalpy of up to 136.6 J/g, representing 75.8% of the heat storage capacity of pristine LA (180.2 J/g), a value surpassing all previously reported core–sheath fibers. Scanning electron microscopy revealed uniform LAPS nanofibers free of surface LA until the core LA feed rate reached 1.3 mL/h. As the core LA feed rate increased, the fiber diameter shrank from 2.24 ± 0.31 to 0.58 ± 0.45 μm. Infrared spectra demonstrated a proportional increase in the LA content with rising core LA injection rates. Thermogravimetric analysis found the maximum core LA content in core–sheath nanofibers to be 75.0%. Differential scanning calorimetry thermograms displayed a trend line shift upon LA leakage for LA _1.3PS nanofibers. LAPS fibers containing 75.0% LA effectively maintained consistent cycling stability and reusability across 100 heating–cooling cycles (20–60 °C) without heat storage deterioration. The core LA remained securely within the PS sheath after 100 cycles, and the LAPS nanofibers retained an excellent structural integrity without rupture. The energy-dense and form-stable LAPS core–sheath nanofibers have great potential for various thermal energy storage applications, such as building insulation, smart textiles, and electronic cooling systems, providing efficient temperature regulation and energy conservation.

Abstract

Coaxial electrospinning was used to efficiently and securely encapsulate a natural phase change material in polymer core–sheath nanofibers for sustainable thermal energy storage.