Enhanced dielectric and mechanical properties of polylactic acid/polycaprolactone blends by introducing double‐layer carbon nanofillers

Abstract To overcome the issues of poor toughness and low dielectric constant associated with PLA, which limit its application in the electronics industry, we introduced an insulating polydopamine (PDA) layer on the surface of core‐shell nickel‐coated carbon nanotube (Ni‐CNT) and nickel‐coated graphene (Ni‐GRA). Through a double‐layer structural design approach, we successfully prepared polylactic acid (PLA)/polycaprolactone (PCL) blends that exhibit high dielectric constant (ε’) and low dielectric loss (tanδ). This innovative design led to impressive impact strengths of 29.41 kJ/m 2 for PLA/PCL/4Ni‐GRAs and 22.54 kJ/m 2 for PLA/PCL/4Ni‐CNTs. PDA enhanced the interfacial interactions between the filler and matrix, which improved the dispersion of Ni‐CNTs and Ni‐GRAs and contributed to the mechanical properties of the PLA/PCL blends. Simultaneously, PLA/PCL/4Ni‐CNTs and PLA/PCL/4Ni‐GRAs exhibited commendable integrated dielectric properties. The PDA@fillers form microcapacitors with the polymer matrix and the conductive Ni layer enhances ε’ and reduces the conductivity difference between fillers. Furthermore, the insulating PDA layer contributed to improved dispersion, inhibition of charge carrier migration, and reduction in tanδ. At 1000 Hz, the ε ′ of PLA/PCL/4Ni‐CNTs and PLA/PCL/4Ni‐GRAs increased to 88.3 and 124.6, respectively, and the tanδ values remained below 1, indicating minimal dielectric loss. This provides a promising direction for eco‐friendly materials with enhanced dielectric and mechanical properties.