TEMPO-oxidised cellulose nanofibrils from bacterial cellulose: how the cellulose source influences the gelation mechanisms
Abstract
TEMPO-oxidation of cellulose is used to form water-dispersible, negatively charged nanofibrils. It is known the type of cellulose source influences the yield of the TEMPO-oxidation, the number of carboxylate groups and the crystallinity index. In this paper, we aim at evidencing its influence on water-based formulation. Dispersions of TEMPO-oxidised bacterial cellulose nanofibrils (OBCNF) in aqueous suspensions were studied both using small angle x-ray scattering (SAXS) and rheology as a function of concentration in nanofibrils, addition of NaCl or sodium dodecyl sulphate (SDS), and these results were compared with previously studied oxidised cellulose nanofibrils (OCNF) from wood pulp. Under the same oxidation procedure, OBCNF exhibit slightly higher oxidation degree than their OCNF counterparts (29% and ζ-potential=-56±4 mV versus 25% and -48±2 mV). They also exhibit much larger length as seen in TEM, with an almost ribbon-like architecture whereas OCNF form short stiff nanorods. As OCNF, OBCNF suspensions can gel by increasing nanofibril concentration, or upon addition of salt or SDS. Yet, the gels formed upon increased concentration see a frequency dependence of their storage and loss moduli associated with a yield strain at low yield (ca. 1%), consistent with the formation of a weak entangled network, while no interactions are observed in SAXS; whereas OCNF gels were formed due to the rise of repulsive interactions between nanofibrils. Upon salt/SDS addition, the gelation mechanisms consist of a gradual charge screening of the carboxyl groups and a rise of attractive interactions between OBCNF with salt, and a depletion attraction due to the presence of negatively-charged micelles for SDS, which are the same mechanisms observed for OCNF. Yet, the rheological properties are strongly dependant on the type of nanofibrils used. OBCNF gels exhibit in most cases higher viscosity and storage moduli than their OCNF counterparts for similar formulation conditions, a higher tolerance to salt before syneresis or to SDS before gelation, which allows for a finer tuning of their rheological properties, relevant for the design of health-care products.
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BibTeX
@article{schmitt2026tempooxidised,
title = {{TEMPO-oxidised cellulose nanofibrils from bacterial cellulose: how the cellulose source influences the gelation mechanisms}},
author = {Julien Schmitt and Vincenzo Calabrese and Kazi M Zakir Hossain and Janet L Scott and Karen J Edler},
journal = {Physical Chemistry Chemical Physics},
year = {2026},
month = sep,
doi = {10.1039/d6cp02653b},
url = {https://hal.science/hal-05778908v1},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - JOUR
TI - TEMPO-oxidised cellulose nanofibrils from bacterial cellulose: how the cellulose source influences the gelation mechanisms
AU - Julien Schmitt
AU - Vincenzo Calabrese
AU - Kazi M Zakir Hossain
AU - Janet L Scott
AU - Karen J Edler
PY - 2026
DA - 2026/09/30
JO - Physical Chemistry Chemical Physics
DO - 10.1039/d6cp02653b
UR - https://hal.science/hal-05778908v1
AB - TEMPO-oxidation of cellulose is used to form water-dispersible, negatively charged nanofibrils. It is known the type of cellulose source influences the yield of the TEMPO-oxidation, the number of carboxylate groups and the crystallinity index. In this paper, we aim at evidencing its influence on water-based formulation. Dispersions of TEMPO-oxidised bacterial cellulose nanofibrils (OBCNF) in aqueous suspensions were studied both using small angle x-ray scattering (SAXS) and rheology as a function of concentration in nanofibrils, addition of NaCl or sodium dodecyl sulphate (SDS), and these results were compared with previously studied oxidised cellulose nanofibrils (OCNF) from wood pulp. Under the same oxidation procedure, OBCNF exhibit slightly higher oxidation degree than their OCNF counterparts (29% and ζ-potential=-56±4 mV versus 25% and -48±2 mV). They also exhibit much larger length as seen in TEM, with an almost ribbon-like architecture whereas OCNF form short stiff nanorods. As OCNF, OBCNF suspensions can gel by increasing nanofibril concentration, or upon addition of salt or SDS. Yet, the gels formed upon increased concentration see a frequency dependence of their storage and loss moduli associated with a yield strain at low yield (ca. 1%), consistent with the formation of a weak entangled network, while no interactions are observed in SAXS; whereas OCNF gels were formed due to the rise of repulsive interactions between nanofibrils. Upon salt/SDS addition, the gelation mechanisms consist of a gradual charge screening of the carboxyl groups and a rise of attractive interactions between OBCNF with salt, and a depletion attraction due to the presence of negatively-charged micelles for SDS, which are the same mechanisms observed for OCNF. Yet, the rheological properties are strongly dependant on the type of nanofibrils used. OBCNF gels exhibit in most cases higher viscosity and storage moduli than their OCNF counterparts for similar formulation conditions, a higher tolerance to salt before syneresis or to SDS before gelation, which allows for a finer tuning of their rheological properties, relevant for the design of health-care products.
SN - 1463-9076
SN - 1463-9084
ER -