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Conductive polymer composites (CPCs) enjoy broad industrial applications such as electrostatic discharge (ESD) protection. Herein, we constructed CPCs by first solution blending graphene nanoplatelets (GNPs) into a miscible blend of poly(methyl methacrylate) (PMMA) and poly(styrene-co-acrylonitrile) (SAN) and then inducing PMMA/SAN spinodal decomposition by annealing well above the lower critical solution temperature. The resulting composite showed spatially regular, co-continuous polymer domains, in which GNPs preferentially localized within the SAN-rich phase and formed a conductive network. We found that GNPs induced local nucleation of SAN into surface layers of ∼4Rg in thickness. Small PMMA domains formed next to these SAN layers and were stable against long annealing times. As a result, GNPs created local blend morphologies that were different from the bulk morphology arising from spinodal decomposition alone. During annealing, GNPs suppressed domain coarsening and preserved the co-continuous morphology, while their connectivity in the polymer matrix was improved. Additionally, inducing PMMA/SAN phase separation significantly increased the ternary blend's electrical conductivity by over 5 orders of magnitude. Compared to the conventional approach of CPC manufacture of compounding carbon black into a homopolymer matrix, our approach achieved bulk electrical conductivity of ∼10-8 S/cm at 1 wt % GNP loading, rendering this system suitable for ESD protection.
Bibliographical noteFunding Information:
We gratefully acknowledge funding from the National Science Foundation (CMMI-1661666). Parts of this work were performed in the Characterization Facility, University of Minnesota, a member of the NSF-funded Materials Research Facilities Network ( www.mrfn.org ) via the MRSEC program.
Copyright © 2019 American Chemical Society.
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- Period 6