In situ one-step construction of monolithic silica aerogel-based composite phase change materials for thermal protection

Currently, numerous studies are devoted to the pursuit of thermal conductivity enhancement of phase change materials (PCMs). On the contrary, few researches are reported to reduce the thermal conductivity of PCMs. Generally, the PCMs with reduced thermal conductivity have great potential in thermal protection application. Herein, we propose a novel in situ one-step strategy to facilely prepare monolithic silica aerogel-based composite PCMs. The silica aerogels possess low thermal conductivity and are used to encapsulate PCMs to prepare composite PCMs, such as polyethylene glycol (PEG) or octadecanol. Compare with PEG2000@silica aerogel, the resulting monolithic octadecanol@silica aerogel have low thermal conductivity (0.12 W m−1 K−1), high latent heat (127.73 J/g), large compressive strength (11 MPa), good hydrophobicity (contact angle 124°) and superior thermal cycling stability. This monolithic silica aerogel-based composite PCMs could prolong heat preservation duration due to the synergistic effect between low thermal conductivity and high latent heat of composite PCMs, showing potential promise for direct application to the thermal insulation and thermal protection device. More importantly, this in situ one-step synthesis strategy is universal for different types of PCMs.