Facile preparation of lightweight high-strength biodegradable polymer/multi-walled carbon nanotubes nanocomposite foams for electromagnetic interference shielding

Lightweight conductive polymer composites (CPCs) have been considered as the most promising alternatives to metal-based shields for electromagnetic interference (EMI) shielding application but still face non-degradation issues. We report a facile, inexpensive and green method to implement lightweight biodegradable poly (l-lactic acid) (PLLA)-multiwalled carbon nanotubes (MWCNTs) nanocomposite foams using a combinatorial technology of pressure-induced flow (PIF) processing and supercritical carbon dioxide (Sc-CO2) foaming. Such low-density (∼0.3 g/cm3), low thickness (∼2.5 mm), high compressive strength (∼54 MPa g−1 cm3)) and highly conductive (∼3.4 S m−1) PLLA-MWCNT nanocomposite foams were first reported as an EMI shielding material: it presents high performance EMI shielding with a remarkable effectiveness and a corresponding average specific EMI SE of ∼23 dB and ∼77 dB g−1 cm3, respectively, with less reflection in the measured X-band frequency region. Considering the simple, low-cost and eco-friendly fabrication process, the lightweight, high-strength and highly conductive biodegradable polymer composite foams are expected to be used as high-performance EMI shielding materials in areas such as electronics, automobiles and packaging.