Ionic Liquid-Graphene Oxide for Strengthening Microwave Curing Epoxy Composites

The challenge for fully exerting the excellent nature of graphene oxide (GO) within polymer composites was to realize its uniform dispersion and strong interfacial bonding in the polymer matrix through an efficient surface reduction approach. In this work, via the in situ activation effect of microwaves (MWs), a butyl glycidyl ether-modified ionic liquid (BIL)-GO hybrid was successfully synthesized at an ultrafast speed by introducing BIL into the two-dimensional lamellar structure of GO through chemically induced intercalation and noncovalent functions. Both GO and BIL components of BIL-GO had the positive synergism in absorbing MWs, which contributed much to enhancing its dispersibility in the epoxy (EP) matrix as compared with pristine GO. Superior to GO-filled systems, BIL-GO/EP composites showed lower activation energies (E_a1 and E_a2 reduced by 11.2 and 17.3%, respectively) over the range of cure following inside-out solidification modes because of the introduction of BIL because uniformly dispersed BIL-GO with exfoliated interlayers acted as trap centers of MWs. Additionally, BIL-GO/EP composites possessed a 22.1% increase in the strength of the transverse fiber bundle test over that of GO/EP composites, indicating better BIL-GO/EP interfacial bonding. The obtained results manifested that the advantageous effect of BIL through the in situ activation of MWs was to enhance the interface stress transfer and form a uniform BIL-GO network, thereby significantly enhancing the mechanical, thermal, and electrical properties of BIL-GO composites.