Robust and self-healing polydimethylsiloxane/carbon nanotube foams for electromagnetic interference shielding and thermal insulation

Polymer-based electromagnetic interference (EMI) shielding materials with low density, low thermal conductivity, strong mechanical properties, good self-healing and high shielding performance are ideal candidates for military and aviation applications. However, conflicts between the desired properties result in tremendous challenges in the design and fabrication of these polymer materials. Here, we develop a novel approach to the preparation of excellent elastomeric foams that can meet the aforementioned requirements. A segregated carbon nanotube (CNT) network and porous structure are constructed synchronously in a polydimethylsiloxane (PDMS) matrix by employing a combinatorial procedure of suspension mixing and the template foaming method. The resulting foams exhibit a novel “sea-island” structure, in which the rubber phase with a segregated CNT network and ultrathin-shell expanded polymer microspheres are regarded as the continuous phase and the disperse phase, respectively. The obtained foam possesses an adjustable density (0.26–0.6 g/cm3), considerably low thermal conductivity (0.028–0.064 W/(m·K)), preeminent electrical conductivity (44.23 S/m), outstanding compressive strength (14.67 MPa), and good impact strength (2.80 kJ/m2). Furthermore, the EMI shielding effectiveness is excellent, reaching 44.51 dB, and 88.76% of the shielding effectiveness can be maintained after the self-healing procedure. These results confirm that the obtained foam has great potential for modern electronics and aerospace applications.