Now, an international research group led by scientists from China and Australia has developed an elegant approach that overcomes these difficulties. The technique uses liquid-like CNTs to fabricate homogeneous polymer-based composites through solvent-free processing. Amino-functionalized CNTs behave like a viscous liquid, which is easier to handle and process.

Protective layer

Liquid-like CNTs are individually exfoliated into a liquid mixture of epoxy resin, curing agent and catalyst under mechanical agitation and ultrasonication before curing (see image). Meanwhile, the surface amino groups on the CNTs serve as an activated polyamine curing agent and react with the epoxide groups to form a polymer "protective layer". This prevents the fully dispersed CNTs from re-aggregation during epoxy curing and results in a strong interface with the surrounding matrix.

As a result, the molecular-level integration of liquid-like CNTs into epoxy shows significant improvements in the overall mechanical properties of epoxy composites relative to those composites containing solid CNTs due to poor dispersion and weak interface of the latter.

Full details can be found in the journal Nanotechnology.