Alkylated Nanofibrillated Cellulose/Carbon Nanotubes Aerogels Supported Form-Stable Phase Change Composites with Improved n-Alkanes Loading Capacity and Thermal Conductivity.

The exploitation of phase change materials (PCMs) with excellent shape stability, considerable latent heat storage capacity, and superior thermal conductivity is essential for their applications in heat storage and thermal regulation. Here, form-stable composite PCMs based on n-octacosane, nanofibrillated cellulose (NFC), and carbon nanotubes (CNTs) were successfully obtained by impregnating n-octacosane into the alkylated NFC/CNTs hybrid aerogels. The three-dimensional interconnected porous aerogels could adequately support the melted n-octacosane and prevent the leakage problem due to strong capillary force and surface tension. After treatment with alkylated modification, the affinity between NFC/CNTs aerogels and n-alkanes was significantly improved, resulting in excellent shape stability, improved thermal reliability, and high n-alkanes loading capacity for the as-prepared composite PCMs. The differential scanning calorimetry analysis showed that composite PCMs based on the alkylated NFC/CNTs aerogels exhibited an extremely high phase change enthalpy ranging from 250.9 to 252.9 J/g. Furthermore, the thermal conductivity and photothermal conversion and storage efficiency of the synthesized PCMs were effectively enhanced by the introduction of CNTs. Thus, the synthesized composite PCMs exhibit considerable potential for practical application in heat storage and thermal regulation.