Improved mechanical and EMI shielding properties of PLA/PCL composites by controlling distribution of PIL-modified CNTs

The functionalization and distribution of conductive fillers and the interfacial compatibilization of polymer blends is the basic scientific problem of electromagnetic interference (EMI) shielding composites. Polylactic acid/polycaprolactone (PLA/PCL)-based nanocomposites containing polymerizable ionic liquid copolymer of poly(methoxy poly(ethylene glycol) monomethacrylate-co-1-vinyl-3-ethylimidazolium bromide) (PILs) and multi-walled carbon nanotubes (CNTs) were fabricated by the melt blending. The high affinity of MEPGMA segments of PILs for both phases and the interaction between the imidazole group of PILs and CNTs improved the dispersion and compatibility of CNTs in the matrix. PILs could expand to the interfacial layers as compatibilizers because of the high affinity of MEPGMA groups for polymer phases. The migration of CNTs from PLA to PCL phase was realized by the kinetic control and PIL-modified CNTs were selectively distributed at the co-continuous PLA/PCL interface and PCL phase of the PLA/PCL/4PIL/8CNT-6 m composite with blending time of 6 min. The selective localization of CNTs at interphase significantly can form effective conductive networks at the interface for PLA/PCL/4PIL/8CNT-6 m composite, which increase the electrical conductivity of the composite. The EMI shielding efficiency of the PLA/PCL/4PIL/8CNT-6 m composites, which can reflect and absorb microwaves with multiple times, reaches up to the maximum value 41 dB. Graphical abstract The selective localization of CNTs at interphase forms effective conductive network. EMI SE of the PLA/PCL/4PIL/8CNT-6 m composite displays 41 dB.