Multifunctional Ti₃C₂T_<i>x</i> MXene/boron nitride nanosheet/polydimethylsiloxane nanocomposites with integrated dielectric and electromagnetic interference shielding performance

Driven by accelerated innovations in integrated microelectronics, dielectric nanocomposites with an integrated high dielectric constant, low dielectric loss and high electromagnetic interference (EMI) shielding effectiveness (SE) have emerged as pivotal materials for next-generation electronic devices. Herein, multifunctional Ti₃C₂T_<i>x</i> MXene/boron nitride nanosheet (BNNS)/polydimethylsiloxane (PDMS) nanocomposites with highly anisotropic structures are developed through oriented assembly of two-dimensional Ti₃C₂T_<i>x</i> MXene and BNNSs <i>via</i> a unidirectional freeze-casting strategy. Owing to the highly oriented Ti₃C₂T_<i>x</i> MXene/BNNS skeletons, the Ti₃C₂T_<i>x</i> MXene/BNNS/PDMS nanocomposites exhibit excellent dielectric performance with a high dielectric constant (<i>ε</i>) of 31.8 coupled with a remarkably low dielectric loss (tan <i>δ</i>) of 2.8 × 10^-3, yielding an unprecedented dielectric constant to loss ratio of 10⁴. Moreover, the oriented porous structure of Ti₃C₂T_<i>x</i> MXene/BNNS aerogel endows the Ti₃C₂T_<i>x</i> MXene/BNNS/PDMS nanocomposite with an exceptional EMI SE value of 39.9 dB across the X-band frequency range (8.2-12.4 GHz). The synergistic design provides a facile strategy to produce next-generation electronic systems requiring concurrent energy storage and electromagnetic compatibility.