Broadband microwave-absorbing and energy-storing composite foam with pomegranate-like microstructure created from Pickering emulsion method

• Published in: Composites. Part A, Applied science and manufacturing Applied science and manufacturing, 2021-10, Vol.149, p.106551, Article 106551
• Main Authors: He, Yingying, Xie, Huihong, Li, Shuai, Liao, Daogui, Wang, Yanan, Chen, Yunhua, Zhou, Li, Yu, Chuanbai, Liu, Hongxia
• Format: Article
• Language: English
• Subjects: A. Foams; A. Multifunctional composites; B. Microstructures; Pickering emulsion
• ISSN: 1359-835X; 1878-5840
• DOI: 10.1016/j.compositesa.2021.106551

In this study, Pickering emulsion combined with in-situ polymerization method was utilized to build a novel microwave absorption foam with ingeniously designed pomegranate-like microstructure. In the CNF/Fe3O4/PW/PPy hybrid foam obtained, a large amount of PW microspheres were embedded and simultaneously wrapped by CNF/Fe3O4/PPy nanocomposite shells. Due to the high phase change enthalpy of the PW microspheres introduced, pomegranate-like microstructure and synergistic effect between PPy and Fe3O4 nanoparticles, the foam possessed multifunctional properties in addition to broadband MA performances such as: (i) the hybrid foam exhibited the excellent microwave absorption performance with reflection loss value of −55.6 dB with thickness of 2.5 mm at 10.6 GHz, and especially the surprising effective bandwidth of 10.0 GHz (8.0–18.0 GHz); (ii) under an irradiation of 1 Sun for 5 min, the surface temperature of hybrid foam can reach up to approximately 98.2 °C, while after turning off the irradiation for 10 min, it can still be maintained at 38.4 °C, higher about 10.0 °C than that of the foam without PW. This work not only opens up a new avenue and inspiration but also affords a facile route to design high performance next-generation microwave absorbing materials in order to apply in many fields as microwave absorption, thermal energy storage systems, and smart building. [Display omitted] •Multifunctional composite foam was fabricated based on Pickering emulsions.•The foam exihibits pomegranate-like microstructure.•The foam has good microwave absorption and broadband efficient bandwidth of 10.0 GHz.•The foam possesses excellent photo-thermal conversion and energy storage ability. Rational design and construction on the microstructure of multifunctional microwave absorbing materials are significant strategy for upgrading their performances. Here, multifunctional hybrid foam with pomegranate-like microstructure are fabricated, which based on paraffin wax (PW)-in-water Pickering emulsion stabilized by cellulose nanofibrils (CNF). The in-situ polymerization of pyrrole monomer induced the creation of CNF/Fe3O4/PW/polypyrrole (PPy) hybrid foam, wherein PW microspheres were covered with CNF/Fe3O4/PPy nanocomposite shells. The obtained foam exhibited excellent microwave absorption performance with a reflection value (RL) of −55.6 dB and broadband bandwidth of 10.0 GHz (8.0–18.0 GHz). Owing to the specificity in the structure of hybrid foams with embedded PW microspheres