Nano- and Microscale Design of Electrically Conductive Bacterial Cellulose/PEDOT Cryogels for Electromagnetic Interference Shielding

Exploiting conductive biobased polymer nanocomposites for electromagnetic interference (EMI) shielding is a rapidly evolving research area. In this study, we systematically fine-tune the nano- and microstructural features of bacterial cellulose (BC) modified with poly(3,4-ethylenedioxythiophene) (PEDOT) for EMI shielding applications. First, to investigate the effect of nanostructure, PEDOT is incorporated into the BC matrix using two methods: chemical vapor polymerization (CVP) and in situ polymerization. The CVP method produces more uniform and denser BC-PEDOT nanocomposites, resulting in cryogels with higher electrical conductivity and total EMI shielding effectiveness (SET) (52 +/- 2 S/m, 37 dB) compared to those of the in situ polymerized BC-PEDOT cryogels (7 +/- 1.5 S/m, 27 dB). The cryogels' microstructure is then adjusted to control the EMI shielding mechanisms by applying different drying methods: freeze-drying, air-drying, and hybrid freeze- and air-drying. Our results indicate that the more energy-efficient air-drying method enhances the reflection-dominant EMI shielding mechanism, with a slight increase in total shielding effectiveness. The drying conditions also affect the final mechanical properties of the samples. Overall, this study demonstrates that BC-PEDOT nanocomposites are excellent candidates for EMI shielding applications.