Poly(acrylic acid)-wrapped multi-walled carbon nanotubes composite solubilization inwater: definitive spectroscopic properties

Abstract

A non-conjugated polymeric poly(acrylic acid) (PAA) is shown to efficiently form a stablecomposite with multi-walled carbon nanotubes (MWNTs). The prepared PAA-wrappedMWNTs composite is readily soluble and stable in water. The PAA–MWNTs compositeexhibits interesting optical properties. FT-IR spectra show that the characteristicpeaks for MWNTs are unchanged, and new chemical bonds are not formed inPAA–MWNTs, indicating that the electronic structures of the MWNTs are still intactafter polymer wrapping. The obvious blue-shift of the peak at 266 nm for theC = C double bonds of pristine MWNTs upon polymer-wrapping, the systematic upshiftin peak position and the enhancement in the band intensities of characteristicRaman bands of MWNTs after winding with PAA as well as the disappearance of1H NMR spectra for the wrapped polymer in PAA-MWNTs composite were observed, whichindicate that there is strong binding of PAA to MWNTs surface via the hydropholicattraction between PAA and MWNTs. The as-prepared PAA-MWNTs dispersions couldfacilitate the processing of the nanotubes into composites with high nanotube loading forbioelectronic devices and biological applications where a water-based environment isneeded.