The Effect of Controlled Pore Structure of <scp>PDMS</scp> Foam via Template Method on the Enhanced Absorbing Performance

ABSTRACT A simple and flexible approach of the template etching method was used to prepare the porous PDMS foam, whereas the foam pore structures were precisely controlled via template agents of PMMA, NaCl, and sugar. The SEM results indicated that the porous structure is uniform, with a size of approximately 140–150 μm. The pore morphologies are hexagonal (H), cubic (C), and spherical (B), respectively. The significance of this paper is to investigate the effect of pore morphology on the absorbing properties. Compared with CFs and HFs, the absorbing foam of BFs showed an excellent impedance match and absorbing performance. The minimum reflection loss (RL min ) of BFs is −43.39 dB, where −21.05 dB is of CFs and −33.58 dB of HFs. In order to further broaden the absorbing frequency band, a double‐layer structure absorbing foam was constructed via the combination of BFs with CFs and HFs, respectively, where BFs were selected as the upper layer due to the good impedance matching. Compared to the best bandwidth of the single layer of 5.8 GHz (BFs), the double‐layer BFs‐CFs and BFs‐HFs reached a wide frequency band of 6.84 and 6.05 GHz, respectively, indicating that constructing a double‐layer structure is feasible and meaningful for broadening the absorbing frequency band.