Self-healing composite coating fabricated with a cystamine crosslinked cellulose nanocrystal stabilized Pickering emulsion

Guofan Xu, Amaka J. Onyianta, Jean-Charles Eloi, Robert L. Harniman, Jude Laverock, Ian Bond, Onajite Abafe Diejomaoh, Todor T. Koev, Yaroslav Z. Khimyak, Stephen J. Eichhorn

Research output: Contribution to journalArticlepeer-review

Abstract

A gelled Pickering emulsion system was fabricated by first stabilizing linseed oil droplets in water with dialdehyde cellulose nanocrystals (DACNCs) and then cross-linking with cystamine. Cross-linking of the DACNCs was shown to occur by a reaction between the amine groups on cystamine and the aldehyde groups on the CNCs, causing gelation of the nanocellulose suspension. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to characterize the cystamine-cross-linked CNCs (cysCNCs), demonstrating their presence. Transmission electron microscopy images evidenced that cross-linking between cysCNCs took place. This cross-linking was utilized in a linseed oil-in-water Pickering emulsion system, creating a novel gelled Pickering emulsion system. The rheological properties of both DACNC suspensions and nanocellulose-stabilized Pickering emulsions were monitored during the cross-linking reaction. Dynamic light scattering and confocal laser scanning microscopy (CLSM) of the Pickering emulsion before gelling imaged CNC-stabilized oil droplets along with isolated CNC rods and CNC clusters, which had not been adsorbed to the oil droplet surfaces. Atomic force microscopy imaging of the air-dried gelled Pickering emulsion also demonstrated the presence of free CNCs alongside the oil droplets and the cross-linked CNC network directly at the oil-water interface on the oil droplet surfaces. Finally, these gelled Pickering emulsions were mixed with poly(vinyl alcohol) solutions and fabricated into self-healing composite coating systems. These self-healing composite coatings were then scratched and viewed under both an optical microscope and a scanning electron microscope before and after self-healing. The linseed oil was demonstrated to leak into the scratches, healing the gap automatically and giving a practical approach for a variety of potential applications.

Original languageEnglish
Pages (from-to)715-728
Number of pages14
JournalBiomacromolecules
Volume25
Issue number2
Early online date25 Jan 2024
DOIs
Publication statusPublished - 12 Feb 2024

Keywords

  • Cystamine
  • Cellulose nanocrystals
  • Pickering emulsion
  • Gel
  • Poly(vinyl alcohol)
  • Self-healing

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