Ion-induced assemblies of highly anisotropic nanoparticles are governed by ion–ion correlation and specific ion effects

Benselfelt, Tobias; Nordenström, Malin; Hamedi, Mahiar; Wågberg, Lars

doi:10.1039/c8nr10175b

Cited by 52 publications

(105 citation statements)

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“…This observation indicates that CNFs form stronger structures using CaCl 2 than NaCl, which is in accordance with previously reported studies. [58] For the sake of clarity, the aerogels will, from now on, be named according to following notation: "x:y z × 10 −3 m S", where x corresponds to the weight fraction of CNFs, y the weight fraction of alginate, z the added ionic strength, and S is the type of salt added; NaCl or CaCl 2 .…”

Section: Principles Of Aerogel Makingmentioning

confidence: 99%

Ambient‐Dried, 3D‐Printable and Electrically Conducting Cellulose Nanofiber Aerogels by Inclusion of Functional Polymers

Françon

Wang

Marais

et al. 2020

Adv Funct Materials

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105

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This study presents a novel, green, and efficient way of preparing crosslinked aerogels from cellulose nanofibers (CNFs) and alginate using non‐covalent chemistry. This new process can ultimately facilitate the fast, continuous, and large‐scale production of porous, light‐weight materials as it does not require freeze‐drying, supercritical CO2 drying, or any environmentally harmful crosslinking chemistries. The reported preparation procedure relies solely on the successive freezing, solvent‐exchange, and ambient drying of composite CNF‐alginate gels. The presented findings suggest that a highly‐porous structure can be preserved throughout the process by simply controlling the ionic strength of the gel. Aerogels with tunable densities (23–38 kg m−3) and compressive moduli (97–275 kPa) can be prepared by using different CNF concentrations. These low‐density networks have a unique combination of formability (using molding or 3D‐printing) and wet‐stability (when ion exchanged to calcium ions). To demonstrate their use in advanced wet applications, the printed aerogels are functionalized with very high loadings of conducting poly(3,4‐ethylenedioxythiophene):tosylate (PEDOT:TOS) polymer by using a novel in situ polymerization approach. In‐depth material characterization reveals that these aerogels have the potential to be used in not only energy storage applications (specific capacitance of 78 F g−1), but also as mechanical‐strain and humidity sensors.

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Section: Principles Of Aerogel Makingmentioning

confidence: 99%

Ambient‐Dried, 3D‐Printable and Electrically Conducting Cellulose Nanofiber Aerogels by Inclusion of Functional Polymers

Françon

Wang

Marais

et al. 2020

Adv Funct Materials

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105

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“…This change in the dissociation, in turn, reduces the ionic swelling and increases the integrity of the material in water. This effect is visually observed in materials treated with Fe 3+ , since Fe 3+ complexes change color with pH and therefore act as an indirect measure of the pH of the local environment …”

Section: Introductionmentioning

confidence: 97%

“…In our previous work, we suggested that the attractive interaction in the presence of multivalent ions can essentially be explained by four different mechanisms. These mechanisms are illustrated in Figure and consist of a fundamental driving force from ion–ion correlation, which allows for the specific ion effects: dispersion interactions and metal–ligand complexes, in combination with a local acidic environment that changes the dissociation of the charged groups, to further “lock” the fibril network.…”

Section: Introductionmentioning

confidence: 99%

“…Illustrations of the mechanisms behind the attractive interaction between CNFs in the presence of different counter‐ions in the wet films, including ion–ion correlation and specific ion effects: dispersion interactions, metal–ligand complexes, and a local acidic environment …”

Section: Introductionmentioning

confidence: 99%

“…We do this by measuring the stress–strain relation of wet CNF films treated with different multivalent metal‐ions, and we relate the wet modulus and work‐to‐rupture to the valency and polarizability of the counter‐ion, and the ability to form complexes, which are important parameters for the mechanisms. The aim has been to determine the relationship between the specific ion: Ba 2+ , Ca 2+ , Mg 2+ , Mn 2+ , Zn 2+ , Cu 2+ , Al 3+ , or Fe 3+ , the interfibril attraction estimated from the swelling of the films, and the mechanical properties of CNF films saturated with water. We propose a fiber network model to investigate the relationship between swelling and wet modulus, and to describe the elastoplastic behavior using the estimated friction force between fibrils.…”

Section: Introductionmentioning

confidence: 99%

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Explaining the Exceptional Wet Integrity of Transparent Cellulose Nanofibril Films in the Presence of Multivalent Ions—Suitable Substrates for Biointerfaces

Benselfelt

Nordenström

Lindström

et al. 2019

Adv Materials Inter

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pretreatment to introduce charged groups, such as carboxylates or phosphate esters. This treatment facilitates the liberation and improves the colloidal stability of CNF dispersions. [1][2][3] Materials prepared from CNFs, such as aerogels, [4] films, [5] and filaments, [6,7] have an impressive strength in the dry state, but when exposed to moist air or liquid water they become weak and have poor dimensional integrity. These detrimental effects are caused by interactions of the water molecules with the hydrophilic surface of CNFs, which weaken the interfibrillar joints. In the presence of condensed water, the ionic groups on the surface of the CNF also generate an osmotic swelling pressure inside the material so that it expands and becomes further weakened. For most practical applications of CNF materials, it is crucial to reduce this sensitivity to moisture.Introducing covalent crosslinking is a possibility, but a potentially more convenient way to minimize their sensitivity to water is to treat CNF-based materials with multivalent ions, which induce an attractive interaction between the fibrils. It has been suggested that the mechanism of this attraction is crosslinking via metal-ligand complexes, or ionic bridges ("salt" bridges) between the multivalent ion and the carboxylate groups on the surfaces of two or more CNFs. [8][9][10][11] However, the salt bridge model is simplistic, and the observed data do not fully follow the trend of complex stability for divalent and trivalent ions. [12,13] This indicates that there are additional contributions to the attraction between CNFs in the presence of multivalent ions, and these contributions must be identified and characterized to explain the observed properties.In our previous work, [14] we suggested that the attractive interaction in the presence of multivalent ions can essentially be explained by four different mechanisms. These mechanisms are illustrated in Figure 1 and consist of a fundamental driving force from ion-ion correlation, [15][16][17] which allows for the specific ion effects: dispersion interactions [18,19] and metal-ligand complexes, [10,20] in combination with a local acidic environment that changes the dissociation of the charged groups, to further "lock" the fibril network. The most important parameters that govern these mechanisms are the valency (ion-ion correlation) [21] and polarizability (dispersion interactions) [22] of the counter-ions, and the ability of the ion to form complexes with Cellulose nanofibrils (CNFs) assemble into water-resilient materials in the presence of multivalent counter-ions. The essential mechanisms behind these assemblies are ion-ion correlation and specific ion effects. A network model shows that the interfibril attraction indirectly influences the wet modulus by a fourth power relationship to the solidity of the network (E w ∝ φ 4 ). Ions that induce both ion-ion correlation and specific ion effects significantly reduce the swelling of the films, and due to the nonlinear relationship dramatically increase the wet...

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Dynamic Networks of Cellulose Nanofibrils Enable Highly Conductive and Strong Polymer Gel Electrolytes for Lithium‐Ion Batteries

Wang

Heasman

Rostami

et al. 2023

Adv Funct Materials

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Tunable dynamic networks of cellulose nanofibrils (CNFs) are utilized to prepare high‐performance polymer gel electrolytes. By swelling an anisotropically dewatered, but never dried, CNF gel in acidic salt solutions, a highly sparse network is constructed with a fraction of CNFs as low as 0.9%, taking advantage of the very high aspect ratio and the ultra‐thin thickness of the CNFs (micrometers long and 2–4 nm thick). These CNF networks expose high interfacial areas and can accommodate massive amounts of the ionic conductive liquid polyethylene glycol‐based electrolyte into strong homogeneous gel electrolytes. In addition to the reinforced mechanical properties, the presence of the CNFs simultaneously enhances the ionic conductivity due to their excellent strong water‐binding capacity according to computational simulations. This strategy renders the electrolyte a room‐temperature ionic conductivity of 0.61 ± 0.12 mS cm−1 which is one of the highest among polymer gel electrolytes. The electrolyte shows superior performances as a separator for lithium iron phosphate half‐cells in high specific capacity (161 mAh g−1 at 0.1C), excellent rate capability (5C), and cycling stability (94% capacity retention after 300 cycles at 1C) at 60 °C, as well as stable room temperature cycling performance and considerably improved safety compared with commercial liquid electrolyte systems.

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Ion-induced assemblies of highly anisotropic nanoparticles are governed by ion–ion correlation and specific ion effects

Abstract: Ion-induced assemblies of highly anisotropic nanoparticles can be explained by a model consisting of ion–ion correlation and specific ion effects: dispersion interactions, metal–ligand complexes, and local acidic environments.

Cited by 52 publications

References 40 publications

Ambient‐Dried, 3D‐Printable and Electrically Conducting Cellulose Nanofiber Aerogels by Inclusion of Functional Polymers

Ambient‐Dried, 3D‐Printable and Electrically Conducting Cellulose Nanofiber Aerogels by Inclusion of Functional Polymers

Explaining the Exceptional Wet Integrity of Transparent Cellulose Nanofibril Films in the Presence of Multivalent Ions—Suitable Substrates for Biointerfaces

Dynamic Networks of Cellulose Nanofibrils Enable Highly Conductive and Strong Polymer Gel Electrolytes for Lithium‐Ion Batteries

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