Preparation and characterization of octadecane/polyurea nanocapsule-embedded poly(ethylene oxide) nanofibers

This article describes the preparation and characterization of latent heat storage poly(ethylene oxide) nanofibers (LHS-PEO nanofibers) with octadecane/polyurea (PCM/PU) nanocapsules. PCM/PU nanocapsules were prepared by interfacial polycondensation from toluene 2,4-diisocyanate and ethylene diamine in a resin-fortified emulsion system. LHS-PEO nanofibers were prepared using an electrospinning procedure with varying PCM/PU nanocapsules content, i.e., from 0 to 8 wt %. The PCM/PU nanocapsules were polydisperse with an average diameter of 200 nm. The melting and freezing temperatures were determined as 23.7 and 28.2°C, respectively, and the corresponding latent heats were determined as 123.4 and 124.1 kJ kg^-1, respectively. The encapsulation efficiency of the PCM/PU nanocapsules was 78.1%. The latent heat capacity of the LHS-PEO nanofibers increased as the PCM/PU nanocapsules content increased. Defects, such as holes and disconnection of the nanofibers, were observed, particularly inside the LHS-PEO nanofibers. For packaging applications, mats were fabricated from the nanocapsules-embedded nanofibers with varying nanocapsule content and the mats' surface temperatures were monitored with a thermal imaging camera. The results proved the feasibility of using the LHS-PEO nanofibers for thermal energy storage and functional packaging materials.