Self-assembled three-dimensional structure of epoxy/polyethersulphone/silver adhesives with electrical conductivity

Diglycidyl ethers of bisphenol-A (DGEBA)/4,4'-diaminodiphenylmethane (DDM)/polyethersulphone (PES) blends were prepared as matrix resins for electrically conductive adhesives containing silver (Ag) fillers. The epoxy/PES blends formed co-continuous phase structures from initial homogeneous solutions via reaction-induced phase separation during the curing process. The Ag fillers were selectively localized in the epoxy-rich phases that had high affinity toward the surface of the Ag fillers. The co-continuous phase structures of the epoxy/PES blends acted as templates for the three-dimensional continuous structures of the Ag fillers. The self-assembled structures of the Ag fillers were connected in a continuous phase that possessed high electrical conductivity using a relatively small amount of Ag filler. In addition, the epoxy/PES/Ag adhesives had excellent shear adhesive strength. The fracture toughness of the epoxy/PES blends was the source of the high adhesive strength. (C) 2015 Elsevier Ltd. All rights reserved.