Design of a pH-responsive conductive nanocomposite based on MWCNTs stabilized in water by amphiphilic block copolymers

Abstract

Homogeneous water dispersions of multi-walled carbon nanotubes (MWCNTs) were prepared by ultrasonication in the presence of an amphiphilic polystyrene-block-poly(acrylic acid) (PS-b-PAA) copolymer. The ability of PS-b-PAA to disperse and stabilize MWCTNs was investigated by UV-visSEM and zeta potential. The results show that the addition of a styrene block to PAA enhances the dispersion efficiency of the graphitic filler compared to pure PAApossibly due to the nanotube affinity with the polystyrene moiety. Notablythe dispersions show an evident pH-responsive behaviorbeing MWCNTs reaggregation promoted in basic environment. It is worth noting that the responsive character is maintained in solid composites obtained by drop castingthus indicating potential applications in sensing.