Fabrication of Microcellular Polypyrrole/Thermoplastic Polyurethane Composites for Enhanced Microwave Absorption

The construction of cellular structures is regarded as an available strategy to alleviate the weight of electromagnetic wave absorption materials. Herein, a succession of porous polypyrrole/thermoplastic polyurethane (PPy/TPU) composites with various pore structures and filler loadings has been fabricated via chemical oxidative polymerization and supercritical carbon dioxide foaming. With the merits of appropriate saturation pressure and PPy content, pores are homogeneously orchestrated within the TPU foams. When the filler amount is 20 wt·%, three PPy/TPU foams obtain the optimal electromagnetic energy dissipative capability. The PPy/TPU-2 foam exhibits the minimum reflection loss value of −53.11 dB with a thickness of 3.56 mm, while the PPy/TPU-3 foam achieves the widest effective absorption bandwidth of 4.2 GHz at 2.95 mm, encompassing the entire X band. Furthermore, the radar cross section (RCS) simulation of PPy/TPU foams confirms their applied potency in actual scenarios, and the macrostructure design further expands their superiority in electromagnetic wave attenuation. The preeminent wave attenuation capacity is ascribed to multiple reflection and scattering, polarization loss, and conduction loss. This investigation furnishes a facile route to manufacture porous foams, effectuating the integration of light weight and strong microwave absorption.