Adjusting Distribution of Multiwall Carbon Nanotubes in Poly(L-lactide)/Poly(oxymethylene) Blends via Constructing Stereocomplex Crystallites: Toward Conductive and Microwave Shielding Enhancement

Controlling distribution of conductive fillers is a key strategy to construct conductive networks with high efficiency and enhance the conductivity of conductive polymer composites (CPCs). In this work, the distribution of multiwall carbon nanotubes (MWCNTs) in a compatible poly(L-lactide) (PLLA)/poly(oxymethylene) (POM) blend was adjusted by constructing stereocomplex crystallites (SCs). Because of the nucleation effect of SCs, the total crystallinity of the polymer blends increased at the small content of poly(D-lactide) (PDLA). However, the total crystallinity decreased when adding large amount of PDLA due to the confinement effect of SCs. The distribution of MWCNTs could be tuned by the crystallinity of PLLA/POM blends due to the volume-exclusion effect. The electrical conductivity of PLLA/POM/MWCNT composites increased from 1.90 X 10(-3) to 5.56 S/m by adding 2.5 wt % PDLA in PLLA phase. However, the electrical conductivity of the composites decreased at high content of PDLA in PLLA phase because the PLLA and POM crystallization was probably confined by the high amount of SCs. The electromagnetic interference shielding effectiveness reached similar to 28.8 dB in the composites with 3.0 wt % MWCNTs, and the mechanical properties were also improved with the incorporation of proper SCs amount. This work gives a new method to facilitate high-performance CPCs via adjusting distribution of MWCNTs.