Adsorption of P103 Nanoaggregates on Graphene Oxide Nanosheets: Role of Electrostatic Forces in Improving Nanosheet Dispersion

Rahul Patil, Debes Ray, Vinod K. Aswal, Cyrill Bussy, Pratap Bahadur, Sanjay Tiwari (Corresponding)

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Abstract

Graphene oxide (GO) nanosheet suspension is not stable in physiological ionic fluids. To improve stability, surfactants such as Pluronic 103 (P103) have been tested. Going further, this work investigated whether conferring positive surface charge to the surfactant may improve the adsorption ability of P103 micelles on GO sheets. Positive charge on the surfactant was induced by adding dodecyltrimethylammonium bromide (DTAB, a cationic surfactant) in P103 micelles. Subsequent changes in aggregation parameters were investigated through dynamic light scattering and small-angle neutron scattering studies. DTAB incorporation was accompanied by a steady increase in the ζ potential and mixed micelle formation. At high surface charge density, the interaction between adjacent head groups was distorted, which led to dissociation of mixed micelles. Structural developments during the adsorption of mixed micelles on the sheet surface (mass fractal formation) were monitored in terms of changes in the scattering features of aggregates. These fractals emerged as a result of electrostatic interactions. Our observations point toward the existence of small-sized building blocks at low DTAB concentration (≤4 mM). With a superior adsorption, mixed micelles are expected to occupy the intersheet space and maintain a hydration layer. However, at a higher DTAB concentration (≥10 mM), micelles dissociate to produce DTAB-rich unimers and P103-rich loose aggregates. At this point, sheets tend to aggregate in the solvent, regardless of fractal formation.
Original languageEnglish
Pages (from-to)867–873
Number of pages7
JournalLangmuir
Volume37
Issue number2
Early online date5 Jan 2021
DOIs
Publication statusPublished - 19 Jan 2021

Keywords

  • Graphene
  • functionalisation
  • formulation
  • pharmacy

Research Beacons, Institutes and Platforms

  • Advanced materials
  • Advanced Materials in Medicine
  • Lydia Becker Institute
  • National Graphene Institute

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