Lian Bai1, Radhika Sharma1, Catherine Esnaashari1,2, Christopher W. Macosko†1, Xiang Cheng*1
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave. SE, Minneapolis, Minnesota 55455, United States
- Department of Plastics, Iran Polymer and Petrochemical Institute, Tehran, 1497713115, Iran
† Email: macosko@umn.edu
* Email: xcheng@umn.edu
ABSTRACT: Interfacial localization of graphene at the interfaces in cocontinuous polymer blends is shown to be effective in stabilizing the cocontinuous morphology and increasing conductivity with a low electrical percolation threshold. In this study, we created ternary polymer nanocomposites composed of cocontinuous polylactic acid (PLA) and polystyrene (PS) blends intercalated with interfacial graphene nanoplatelets. The resulting conductive nanocomposites show dramatically improved conductivity at low filler loadings and an ultralow percolation threshold. By systemically exploring different melt-compounding sequences and times, we showed that the platelets can be transferred from premixed in the PLA phase to the interface during melt compounding and form a spanning 3D network during annealing. The coverage of graphene platelets on the interface effectively suppresses the coarsening of the cocontinuous structure during annealing and dramatically improves the electrical conductivity of the blends. We quantitatively correlated the transfer of graphene with the change of the morphological, electrical and rheological properties of the polymer nanocomposites.
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