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Monovalent salt and pH-induced gelation of oxidised cellulose nanofibrils and starch networks: Combining rheology and Small-Angle X-Ray Scattering

DOI: 10.3390/polym13060951 DOI Help

Authors: Kazi M. Zakir Hossain (University of Bath) , Vincenzo Calabrese (University of Bath) , Marcelo A. Da Silva (University of Bath) , Saffron J. Bryant (University of Bath) , Julien Schmitt (University of Bath) , Jennifer H. Ahn-Jarvis (Quadram Institute Bioscience) , Frederick J. Warren (Quadram Institute Bioscience) , Yaroslav Z. Khimyak (University of East Anglia) , Janet L. Scott (University of Bath) , Karen J. Edler (University of Bath)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Polymers , VOL 13

State: Published (Approved)
Published: March 2021
Diamond Proposal Number(s): 20409

Open Access Open Access

Abstract: Water quality parameters such as salt content and various pH environments can alter the stability of gels as well as their rheological properties. Here, we investigated the effect of various concentrations of NaCl and different pH environments on the rheological properties of TEMPO-oxidised cellulose nanofibril (OCNF) and starch-based hydrogels. Addition of NaCl caused an increased stiffness of the OCNF:starch (1:1 wt%) blend gels, where salt played an important role in reducing the repulsive OCNF fibrillar interactions. The rheological properties of these hydrogels were unchanged at pH 5.0 to 9.0. However, at lower pH (4.0), the stiffness and viscosity of the OCNF and OCNF:starch gels appeared to increase due to proton-induced fibrillar interactions. In contrast, at higher pH (11.5), syneresis was observed due to the formation of denser and aggregated gel networks. Interactions as well as aggregation behaviour of these hydrogels were explored via ΞΆ-potential measurements. Furthermore, the nanostructure of the OCNF gels was probed using small-angle X-ray scattering (SAXS), where the SAXS patterns showed an increase of slope in the low-q region with increasing salt concentration arising from aggregation due to the screening of the surface charge of the fibrils.

Journal Keywords: cellulose nanofibrils; starch; rheology; SAXS; salt; pH

Subject Areas: Chemistry


Instruments: I22-Small angle scattering & Diffraction

Documents:
polymers-13-00951-v2.pdf

Discipline Tags:

Chemistry

Technical Tags:

Scattering Small Angle X-ray Scattering (SAXS)