Constructing nanopores in poly(oxymethylene)/multi-wall carbon nanotube nanocomposites via poly(l-lactide) assisting for improving electromagnetic interference shielding

• Published in: Journal of colloid and interface science 2020-04, Vol.565, p.536-545
• Main Authors: Li, Jie, Chen, Jia-Li, Tang, Xiao-Hong, Cai, Jie-Hua, Liu, Ji-Hong, Wang, Ming
• Format: Article
• Language: English
• Subjects: Electromagnetic interference shielding; Multi-wall carbon nanotube; Nanoporous structure; Poly(l-lactide); Poly(oxymethylene)
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2020.01.057

Homogeneous nanopores were constructed in poly(oxymethylene)/multi-wall carbon nanotube (POM/MWCNT) nanocomposites by poly(l-lactide) (PLLA) assisting to improve microwave shielding property through the multiple refection and scattering on the walls of the nanopores. [Display omitted] •Nanopores were constructed in the POM/MWCNT composites by PLLA assisting.•High microwave shielding was achieved in the POM/MWCNT composites with nanopores.•Multiple reflections and scattering of microwaves happened on walls of nanopores.•These nanoporous composites maintained high compression and tensile properties. Lightweight and high-performance conductive polymer composites (CPCs) have attracted much attention for electromagnetic interference (EMI) shielding. Herein, the porous structure was constructed in poly(oxymethylene)/multi-wall carbon nanotube (POM/MWCNT) nanocomposites via assisting by poly(l-lactide) (PLLA). First, the POM/PLLA/MWCNT (S-PMLNT) nanocomposites were obtained by melt mixing and compression molding. Second, the nanoporous POM/MWCNT (P-PMNT) nanocomposites were fabricated by selectively dissolving PLLA, solvent exchanging and freeze-drying. Because of well miscible between PLLA and POM, the homogeneous nanopores could be successfully fabricated in the P-PMNT composites by removing the PLLA phase. The multiple reflections and scattering of microwaves happened on the walls of these nanopores, which endowed the P-PMNT nanocomposites having higher EMI shielding effectiveness (SE) in comparison of the S-PMLNT nanocomposites, although the P-PMNT nanocomposites exhibited the lower electrical conductivity. For example, the S-PMLNT samples with 10 wt% MWCNTs showed an EMI SE of 48.1 dB and an electrical conductivity of 333 S/m, which changed to 58.6 dB in EMI SE and 125 S/m in electrical conductivity after removing PLLA phase. Furthermore, the P-PMNT10 nanocomposites had outstanding the EMI normal SE (SE/d) of 29.3 dB mm−1 and the EMI specific shielding effectiveness (SSE/d) of 344.4 dB cm2 g−1 because of their low density. In addition, the P-PMNT nanocomposites maintained high compression and tensile strength simultaneously.