Thin, Lightweight, and Highly Efficient Electromagnetic Interference Shielding Nanocomposites Composed of a π-Conjugated Block Copolymer Nanowire/Multiwalled Carbon Nanotube Bicontinuous Interpenetrating Network.

We developed high-performance electromagnetic interference (EMI) shielding composites by integrating a π-conjugated block polymer system with carbon nanofillers. First, a poly(3-hexylthiophene)-poly(ε-caprolactone) (P3HT-PCL) block copolymer system was synthesized through a combination of Grignard metathesis, tail modifications, and ring-opening polymerization. Controlling the solvent type and aging time resulted in the self-assembly of the P3HT-PCL chains into nanoscale fibers. When multiwalled carbon nanotubes (MWCNTs) were added to the P3HT-PCL solution, the π-π interactions between the thiophene rings of P3HT-PCL and the benzene units of the MWCNTs facilitated the dispersal of MWCNTs in the hybrid solution. Self-assembled P3HT-PCL chains prompted the formation of a nanofibrillar framework, which was beneficial to stabilize the overall structural distribution of the system, thereby synergistically forming a P3HT-PCL/MWCNT composite system with a bicontinuous interpenetrating network. The conductive skeleton formed by the effective connections of one-dimensional geometric MWCNTs made this composite system highly conductive and an excellent EMI shielding material. Moreover, the introduction of PCL helped overcome problems related to the rigid nature of P3HT, facilitating the manufacture of thin, lightweight, and high-performance shielding sheets. The developed composite film was 0.05 mm thick and provided an optimized EMI shielding effectiveness of up to 29.4 dB, effectively blocking nearly 99.89% of the incident waves. The results of this research provide an innovative and promising direction for the development of advanced EMI shielding materials.