Understanding heat driven gelation of anionic cellulose nanofibrils: Combining saturation transfer difference (STD) NMR, small angle X-ray scattering (SAXS) and rheology

Vincenzo Calabrese; Juan C Muñoz-García; Julien Schmitt; Marcelo A da Silva; Janet L Scott; Jesús Angulo; Yaroslav Z Khimyak; Karen J Edler

doi:10.1016/j.jcis.2018.09.085

Understanding heat driven gelation of anionic cellulose nanofibrils: Combining saturation transfer difference (STD) NMR, small angle X-ray scattering (SAXS) and rheology

J Colloid Interface Sci. 2019 Feb 1:535:205-213. doi: 10.1016/j.jcis.2018.09.085. Epub 2018 Sep 25.

Authors

Vincenzo Calabrese¹, Juan C Muñoz-García², Julien Schmitt¹, Marcelo A da Silva¹, Janet L Scott³, Jesús Angulo⁴, Yaroslav Z Khimyak⁵, Karen J Edler⁶

Affiliations

¹ Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK.
² School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
³ Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK; Centre for Sustainable Chemical Technology, University of Bath, Claverton Down, Bath BA2 7AY, UK. Electronic address: j.l.scott@bath.ac.uk.
⁴ School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK. Electronic address: j.angulo@uea.ac.uk.
⁵ School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK. Electronic address: y.khimyak@uea.ac.uk.
⁶ Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK. Electronic address: k.edler@bath.ac.uk.

PMID: 30293046
DOI: 10.1016/j.jcis.2018.09.085

Abstract

A novel mechanism of heat-triggered gelation for oxidised cellulose nanofibrils (OCNF) is reported. We demonstrate that a synergistic approach combining rheology, small-angle X-ray scattering (SAXS) and saturation transfer difference NMR (STD NMR) experiments enables a detailed characterisation of gelation at different length scales. OCNF dispersions experience an increase in solid-like behaviour upon heating as evidenced by rheological studies, associated with enhanced interfibrillar interactions measured using SAXS. Interactions result in an increased fibrillar overlap and increased population of confined water molecules monitored by STD NMR. In comparison, cationic cellulose nanofibrils (produced by reaction of cellulose with trimethylglycidylammonium chloride) were found to be heat-unresponsive.

Keywords: Heat induced gelation; Hydrogel; Rheology; SAXS; Saturation transfer difference NMR; TEMPO oxidised cellulose; Water confinement.