SDS-stabilized graphene nanosheets for highly electrically conductive adhesives

We report sodium dodecyl sulfate (SDS) stabilization of graphene nanosheets, with two different sizes as auxiliary fillers inside the conventional electrically conductive adhesive (ECA) composite. Using this non-covalent modification approach we were able to preserve the single-layer structure of graphene layers and prevent their re-stacking inside the composite, which resulted in a significant electrical conductivity improvement of ECAs at noticeably low filler content. Addition of 1.5wt% small and large SDS-modified graphene into the conventional ECAs with 10wt% silver flakes led to low electrical resistivity values of 5.5×103 Ωcm and 35Ωcm, respectively, while at least 40wt% of silver flakes was required for the conventional ECA to be electrically conductive. A highly conductive ECA with very low bulk resistivity of 1.6×10−5 Ωcm was prepared by adding 1.5wt% of SDS-modified large graphene into the conventional ECA with 80wt% silver flakes which is less than that of eutectic lead-based solders.