Crafting "brick-mud" segregated nanocomposites: a novel approach to superior electromagnetic interference shielding, electrical insulation, and thermal conductivity in biopolymers

As electronic devices continue to be integrated, miniaturized, and operated at higher frequencies, the demand for green, advanced polymer nanocomposites with superior electromagnetic interference (EMI) shielding, thermal conduction, and electrical insulation properties significantly increases. However, achieving such multifunctional nanocomposites is challenging due to the inherent contradiction between electrical and magnetic properties. Biopolymer nanocomposites of polycaprolactone (PCL)/boron nitride (BN)@polylactic acid (PLA)/multi-walled carbon nanotubes (CNTs) ((PCL/BN)@(PLA/CNTs)) exhibit a unique "brick-mud" segregated double-network structure. This configuration effectively separates high-melting-point PLA/CNTs conductive phase from the PCL/BN insulating matrix. PLA/CNTs particles contribute to enhanced EMI shielding by attenuating electromagnetic waves, while also improving insulation by disrupting electron transfer within the PCL/BN phase. Additionally, incorporating conductive CNTs and thermal conductive BN further boosts the thermal conductivity (TC) of the nanocomposites. The structured sample (s-8B8C), which contains 8 wt% BN and 8 wt% CNTs, achieves an EMI shielding effectiveness (SE) of 31.4 dB in the X-band, a TC of 0.6 W m-1 K-1, and a volume resistivity of 7.2 x 1011 Omega cm. In summary, the "brick-mud" segregated structure facilitates the development of advanced biopolymer nanocomposites for electronic applications, leveraging sustainable materials for broad potential use.