Simultaneously Tailoring Surface Energies and Thermal Stabilities of Cellulose Nanocrystals Using Ion Exchange: Effects on Polymer Composite Properties for Transportation, Infrastructure, and Renewable Energy Applications

Douglas M. Fox*, Rebeca S. Rodriguez, Mackenzie N. Devilbiss, Jeremiah Woodcock, Chelsea S. Davis, Robert Sinko, Sinan Keten, Jeffrey W. Gilman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

35 Scopus citations

Abstract

Cellulose nanocrystals (CNCs) have great potential as sustainable reinforcing materials for polymers, but there are a number of obstacles to commercialization that must first be overcome. High levels of water absorption, low thermal stabilities, poor miscibility with nonpolar polymers, and irreversible aggregation of the dried CNCs are among the greatest challenges to producing cellulose nanocrystal-polymer nanocomposites. A simple, scalable technique to modify sulfated cellulose nanocrystals (Na-CNCs) has been developed to address all of these issues. By using an ion exchange process to replace Na+ with imidazolium or phosphonium cations, the surface energy is altered, the thermal stability is increased, and the miscibility of dried CNCs with a nonpolar polymer (epoxy and polystyrene) is enhanced. Characterization of the resulting ion exchanged CNCs (IE-CNCs) using potentiometry, inverse gas chromatography, dynamic vapor sorption, and laser scanning confocal microscopy reveals that the IE-CNCs have lower surface energies, adsorb less water, and have thermal stabilities of up to 100 °C higher than those of prepared protonated cellulose nanocrystals (H-CNCs) and 40 °C higher than that of neutralized Na-CNC. Methyl(triphenyl)phosphonium exchanged cellulose nanocrystals (MePh3P-CNC) adsorbed 30% less water than Na-CNC, retained less water during desorption, and were used to prepare well-dispersed epoxy composites without the aid of a solvent and well-dispersed polystyrene nanocomposites using a melt blending technique at 195 °C. Predictions of dispersion quality and glass transition temperatures from molecular modeling experiments match experimental observations. These fiber-reinforced polymers can be used as lightweight composites in transportation, infrastructure, and renewable energy applications.

Original languageEnglish (US)
Pages (from-to)27270-27281
Number of pages12
JournalACS Applied Materials and Interfaces
Volume8
Issue number40
DOIs
StatePublished - Oct 12 2016

Keywords

  • cellulose nanocrystals
  • dispersion
  • epoxy
  • extrusion
  • ionic liquids
  • polymer composites

ASJC Scopus subject areas

  • Materials Science(all)

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