Design of Flexible Film-Forming Polydopamine/Polypyrrole/Nanodiamond Hierarchical Structure for Broadband Microwave Absorption

Microwave-absorbing materials are widely used in numerous fields, including the military, daily protection, etc. Currently, in addition to being lightweight and highly efficient, good film-forming processing characteristics and environmental stability are also required for the practical application of microwave-absorbing materials, which, in general, are difficult to make compatible. In this paper, a mulberry-like PDA/PPy/ND hierarchical structure was prepared by in situ polymerization. The hierarchical structure showed remarkably enhanced microwave absorption, as well as better flexible film-forming characteristics, thanks to the multiple roles PDA played in the system. The optimal RL peak for PDA/PPy/ND could reach −43.6 dB at 7.58 GHz, which is mainly attributed to the multiple dielectric loss paths and significantly improved impedance-matching characteristics. Furthermore, given the H-bond crosslink, the introduction of PDA also promoted the film formation and dispersion of PDA/PPy/ND in the PVA matrix, forming a water-resistant and flexible film. This work provides a referencing path for the design and practical applications of lightweight microwave-absorbing materials.