Network formation in graphene oxide composites with surface grafted PNIPAM chains in aqueous solution characterized by rheological experiments

Amin Ghavaminejad, Saud Hashmi, Han Ik Joh, Sungho Lee, Youn Sik Lee, Mohammad Vatankhah-Varnoosfaderani, Florian J. Stadler*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

Poly N-isopropyl acrylamide (PNI) radically polymerized in aqueous solution in the presence of graphene oxide (GO) can significantly change the properties of the resulting solution from a regular polymer solution to a soft solid with a GO content of only 0.176 wt% (3 wt% with respect to PNI). However, these properties require the presence of both grafting and supramolecular interactions between polymer chains and hydrophilic groups on GO (-OH, -COOH), proven by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray diffraction and spectroscopy (XRD) and Raman spectra. While very low GO-contents (below 0.05 wt%) only lead to a labile structure, which can be disassembled by shear, higher contents yield composites with solid-like characteristics. This is clearly evident from the rheological behaviour, which changes significantly at a GO content around 0.15 wt%. Intensive shearing destroys the weak network, which cannot reform quickly at lower GO-concentrations, while at intermediate concentrations, restructuring is fast. GO-contents of 0.176 wt% lead to a material behaviour, which almost perfectly recovers from small deformations (creep and creep recovery compliance almost match) but larger deformations lead to permanent damage to the sample.

Original languageEnglish (US)
Pages (from-to)8675-8685
Number of pages11
JournalPhysical Chemistry Chemical Physics
Volume16
Issue number18
DOIs
StatePublished - May 14 2014

ASJC Scopus subject areas

  • General Physics and Astronomy
  • Physical and Theoretical Chemistry

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