(606b) Nanocapsulated Phase Change Materials Based On n-Octadecane Core and Conducting Polymer Shell

Phase change materials (PCMs) play important role in regulating thermal energy by absorbing, storing, and releasing large amounts of latent heat over a defined temperature range during phase transition between liquid and solid. Usually, PCMs were encapsulated within polymeric shell to prevent leakage of liquid phase and various preparation methods of encapsulated PCM have been developed. However, most of developed techniques used micrometer-sized polymeric shells that do not have any function except containing PCMs. In this study, to overcome the limitations of current techniques, we prepared nanoencapsulated PCM by using n-octadecane as a model PCM and polypyrrole (Ppy) as a functional polymeric shell. PCM-PPy core-shell nanoparticles were obtained by miniemulsion polymerization using sodium lauryl sulfate (SLS) as a surfactant and dodecanol as a cosurfactant. Hydrogen peroxide (H2O2) and a trace of ferric chloride (FeCl3) were used as an initiator couple to carry out Fe3+-catalyzed oxidative polymerization, which occurred on the surface of nano-droplets. Average size of PCM-PPy core-shell nanoparticles was about 700 nm. The resultant core-shell structure was first confirmed by scanning electron microscope (SEM), where distinct core-shell morphology was observed after dissolving core PCM with petroleum ether dissolution. Heat capacity of resultant nanoencapsulated PCM was investigated with differential scanning calorimetry (DSC) and it was found that increasing the PCM content lead to enhanced heat capacity (13 J/g ~ 22 J/g). Electrical conductivity is analyzed by 4-probe conductivity meter and it was observed that the doped particles showed a high conductivity in the dry state. In summary, nanoencapsulated PCM was successfully prepared using miniemulsion process and using Ppy as a polymeric shell endowed PCM nanoparticles with conductive property as well as heat storage property, which will open more opportunity for various applications of PCMs.