Sustainable bacterial cellulose reinforced carbon nanotube buckypaper and its multifunctionality for electromagnetic interference shielding, Joule heating and humidity sensing

There is currently enormous and growing demand for sustainable, high-performance and multifunctional electromagnetic interference (EMI) shielding materials for wearable devices. In this work, sustainable resources bacterial cellulose (BC) was selected as reinforced filler of carbon nanotubes (CNT) buckypaper (BP) due to its excellent mechanical strength. A new kind of multifunctional BC reinforced BP (BC-BP) was fabricated through the facile vacuum assisted filtration method. The obtained BC-BP with interpenetrating structure showed outstanding mechanical properties and high electrical conductivity simultaneously. The BC-BP with 50 wt% BC (50%BC) exhibited the tensile strength of 55.78 MPa, the fracture strain of 11.67%, and the electrical conductivity of 16.67 S/cm. The corresponding EMI shielding efficiency (EMI SE) and the specific EMI SE value (SSE/t) of the 50%BC with the thickness of 36 μm was 24.01 dB and 9074 dB⋅cm2/g in the C-band range, respectively. Moreover, the 50%BC also exhibited excellent thermal conductivity (TC) of 7.39 W/mK, Joule heating (124 °C at 6 V), and humidity sensing performance of high sensitivity (10.306%/% RH) in the wide relative humidity range (5–90% RH). In addition to EMI shielding, BC-BP also showed its potential application in the management and monitoring of temperature and humidity. This work provides a new strategy to prepare sustainable, high-performance and multifunctional BC-based EMI shielding material for wearable devices.