Conductive poly(high internal phase emulsion) foams incorporated with polydopamine-coated carbon nanotubes

Abstract

Electrically conductive poly(high internal phase emulsion) (polyHIPE) nanocomposite foams based on poly(styrene-co-divinylbenzene) were prepared by incorporating polydopamine-coated carbon nanotubes (PDA-CNTs). Conductive yet amphiphobic CNTs were modified to PDA-CNTs by coating with PDA on the surface of CNTs to provide hydrophilicity. As a result, it was possible to prepare highly stable HIPEs having PDA-CNT content >10 wt% and resultant polyHIPE foams having enhanced conductivity due to the good dispersion of PDA-CNTs in aqueous phase. The foams made with a water-to-monomer ratio of 10:1 showed well-developed interconnected microcellular structure. With increasing PDA-CNT content, the yield stress and storage modulus of HIPE increased and the cell size of the polyHIPE foam decreased. The electrical percolation threshold was determined to be less than PDA-CNT 1 wt% and the conductivity at PDA-CNT content of 8 wt% was increased to as high as 10−2 Sm−1. Surface modification of CNTs by PDA was very effective in providing electrical conductivity due to their stable dispersion in aqueous phase while keeping the intrinsic properties of CNTs intact.