Flexible phase change film based on lignin-derived porous carbon/Eicosane for wearable thermal management and microwave absorption
Xueqiang Fu, Hong Pan, Lihui Xu, Meng Wang, Meiran Dou, Yingxiu Zhang, Zhangyong Liu, Xinzhe Huang, Yi Teng, Lei Hu, Yihong Wang, Qun Yang
Abstract
A flexible phase-change film with thermal management and microwave absorption capabilities was developed for use in wearable devices . The film was created using a solution casting method based on a porous carbon-loaded eicosane (LP33/EI) material. LP33 served as the porous encapsulation medium, while Eicosane (EI) acted as the phase change component. The flexible substrate was a blend of polyvinyl alcohol (PVA) and bacterial cellulose nanocellulose (BC). The ultrathin film had a thickness of 0.262 mm, and LP33/EI-4 exhibited exceptional mechanical strength of 188 MPa. Testing revealed that the phase transition process had melting and crystallization enthalpies of 134.71 J/g and 126.11 J/g, respectively. The encapsulation structure effectively prevented any leakage during the phase transition process. Under simulated solar irradiation of 200 mW/cm 2 , LP33/EI-4 achieved a photothermal conversion efficiency (η) of 89.46 %. Additionally, the porous LP33 structure and high dielectric loss contributed to remarkable microwave absorption capabilities of −42 dB in the X-band and − 52 dB in the Ku-band. Overall, LP33/EI films demonstrated exceptional performance in thermal management, energy storage, and microwave absorption, making them an ideal choice for a variety of applications in wearable devices.