Organic phase change material (PCM) has an ability to store and release a large amount of energy in a wide range of temperature by the latent heat of fusion upon melting and crystallization. The encapsulation of PCM is necessary to stabilize PCM from an undesirable reaction and leaching. A PCM microcapsule whose shell is made of cellulosic biomass could be an option for better utilization of low-value bioresources. This study aims to prepare microcapsules containing hexadecane (PCM) encapsulated by a cellulosic shell from cellulose nanofibrils (CNF) through a sonochemical technique. High-intensity ultrasonication at the CNF-hexadecane interface created a oil-in-water emulsion, followed by the partial melting and possible crosslinking of CNF to form the cellulosic shell surrounding the hexadecane core. The formation of PCM microcapsules was investigated by visual inspection, FT-IR, and confocal laser scanning microscopy (CLSM) with a selective hydrophobic core fluorescent dyeing. The morphology and size distribution of the microcapsules were studied by SEM and CLSM, which ranged from 4 to 10 µm. Among various weight percents of CNF in water and hexadecane-water ratios, the maximum loading of PCM was determined to be 90% from 0.3% CNF in water and 2:1 water-oil ratio, respectively, by thermal gravimetric analysis. The microcapsules exhibited 132.5 J/g (upon heating) and 141.1 J/g (upon cooling) as stored and released energy, respectively, between -10 and 45 °C. After 200 repeated heating/cooling cycles, the energy loss was only around 1% compared with the initial thermal energy of the microcapsules. Incorporating the PCM microcapsules into TEMPO-oxidized cellulose nanofibril (TOCNF) film increased the thermal stability of microcapsules, which could be useful as a thermal energy storage (TES) material in building applications

Synthesis of microcapsules consisting of a hexadecane core and a cellulosic shell for thermal energy storage

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.