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Aggregation behavior of aqueous cellulose nanocrystals : the effect of inorganic salts

Phan-Xuan, Tuan; Thuresson, Axel LU ; Skepö, Marie LU ; Labrador, Ana LU ; Bordes, Romain and Matic, Aleksandar (2016) In Cellulose 23(6). p.3653-3663
Abstract

Natural anisotropic building-blocks such as cellulose nanocrystals (CNCs) have attracted considerable attention due to their biodegradability and nanometer-size. In this work the colloidal behavior of CNCs, obtained from sulfuric acid hydrolysis of microcrystalline cellulose, has been studied in presence of salts of different valences. The influence on the colloidal stability and nature of aggregates has been investigated for monovalent salts (LiCl, NaCl, KCl, CsCl), divalent salts (CaCl2 and MgCl2), and a trivalent salt (AlCl3), both experimentally by means of turbidity and small angle X-ray scattering (SAXS) measurements, as well as by Monte Carlo simulations using a simple coarse-grained model. For... (More)

Natural anisotropic building-blocks such as cellulose nanocrystals (CNCs) have attracted considerable attention due to their biodegradability and nanometer-size. In this work the colloidal behavior of CNCs, obtained from sulfuric acid hydrolysis of microcrystalline cellulose, has been studied in presence of salts of different valences. The influence on the colloidal stability and nature of aggregates has been investigated for monovalent salts (LiCl, NaCl, KCl, CsCl), divalent salts (CaCl2 and MgCl2), and a trivalent salt (AlCl3), both experimentally by means of turbidity and small angle X-ray scattering (SAXS) measurements, as well as by Monte Carlo simulations using a simple coarse-grained model. For the entire salt series, a critical aggregation concentration (CAC) could be determined by turbidity measurements, as a result of the reduction of effective Coulomb repulsions due to the presence of sulfate groups on the CNC surface. The CACs also followed the Schulze–Hardy law, i.e. the critical aggregation concentration decreased with increasing counterion valence. For the monovalent ions, the CACs followed the trend Li+ > Na+ > K+ > Cs+, which could be rationalized in terms of matching affinities between the cation and the sulfate groups present at the surface of CNCs. From the SAXS measurements it was shown that the density of the aggregates increased with increasing salt concentration and ion valence. In addition, these findings were rationalized by means of simulation, which showed a good correlation with experimental data. The combination of the experimental techniques and the simulations offered insight into interaction-aggregation relationship of CNC suspensions, which is of importance for their structural design applications.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Aggregation, Cellulose nanocrystal, Coarse-grained model, Hofmeister, SAXS, Schulze–Hardy rule
in
Cellulose
volume
23
issue
6
pages
3653 - 3663
publisher
Springer
external identifiers
  • scopus:84989184734
  • wos:000388961200022
ISSN
0969-0239
DOI
10.1007/s10570-016-1080-1
language
English
LU publication?
yes
id
c355d0a6-23d2-4dba-9554-95dca69833e7
date added to LUP
2016-10-28 14:48:33
date last changed
2017-11-12 04:25:35
@article{c355d0a6-23d2-4dba-9554-95dca69833e7,
  abstract     = {<p>Natural anisotropic building-blocks such as cellulose nanocrystals (CNCs) have attracted considerable attention due to their biodegradability and nanometer-size. In this work the colloidal behavior of CNCs, obtained from sulfuric acid hydrolysis of microcrystalline cellulose, has been studied in presence of salts of different valences. The influence on the colloidal stability and nature of aggregates has been investigated for monovalent salts (LiCl, NaCl, KCl, CsCl), divalent salts (CaCl<sub>2</sub> and MgCl<sub>2</sub>), and a trivalent salt (AlCl<sub>3</sub>), both experimentally by means of turbidity and small angle X-ray scattering (SAXS) measurements, as well as by Monte Carlo simulations using a simple coarse-grained model. For the entire salt series, a critical aggregation concentration (CAC) could be determined by turbidity measurements, as a result of the reduction of effective Coulomb repulsions due to the presence of sulfate groups on the CNC surface. The CACs also followed the Schulze–Hardy law, i.e. the critical aggregation concentration decreased with increasing counterion valence. For the monovalent ions, the CACs followed the trend Li<sup>+</sup> &gt; Na<sup>+</sup> &gt; K<sup>+</sup> &gt; Cs<sup>+</sup>, which could be rationalized in terms of matching affinities between the cation and the sulfate groups present at the surface of CNCs. From the SAXS measurements it was shown that the density of the aggregates increased with increasing salt concentration and ion valence. In addition, these findings were rationalized by means of simulation, which showed a good correlation with experimental data. The combination of the experimental techniques and the simulations offered insight into interaction-aggregation relationship of CNC suspensions, which is of importance for their structural design applications.</p>},
  author       = {Phan-Xuan, Tuan and Thuresson, Axel and Skepö, Marie and Labrador, Ana and Bordes, Romain and Matic, Aleksandar},
  issn         = {0969-0239},
  keyword      = {Aggregation,Cellulose nanocrystal,Coarse-grained model,Hofmeister,SAXS,Schulze–Hardy rule},
  language     = {eng},
  number       = {6},
  pages        = {3653--3663},
  publisher    = {Springer},
  series       = {Cellulose},
  title        = {Aggregation behavior of aqueous cellulose nanocrystals : the effect of inorganic salts},
  url          = {http://dx.doi.org/10.1007/s10570-016-1080-1},
  volume       = {23},
  year         = {2016},
}