Elastoplastic behavior of anisotropic, physically crosslinked hydrogel networks comprising stiff, charged fibrils in an electrolyte

Abstract

Fibrillar hydrogels are remarkably stiff, low-density networks that can hold vast amounts of water. These hydrogels can easily be made anisotropic by orienting the fibrils using different methods. Unlike the...

Disulphide Cross‐Linked Ultrashort Peptide Hydrogelator for Water Remediation

“…As fibrillar hydrogels are very different from polymeric hydrogels, it is crucial to know the relationship between fibril dimensions and mechanical properties and mesh size of the network. Kumacheva et al [34] and Benselfelt et al [35] reported the relationship between fibrillar hydrogels and their mechanical properties in this context. Based on the dimensions of the fibrils and their concentration, the mesh size can be estimated, but this is beyond the scope of this manuscript.…”

Electrochemically Controlled Hydrogels with Electrotunable Permeability and Uniaxial Actuation

“…Our model describes the swelling pressure induced by the changed chemical potential when mixing the gel constituents with the solvent (P chem ) and the elastoplastic resistance during the expansion of the network (P net ). For polymer networks, an entropy elastic Gaussian chain model can be used, [10] but there is not yet a quantitative model for enthalpy elastic nanoparticle networks; these are qualitatively described by the initial bending of fibrils under pressure followed by a plastic stick-slip-stick behavior as previously described by Mittal et al and Östmans et al [17,18] In our electroactive nanoparticle gel model (see Supporting Information), P chem is divided into the terms P mix, the free energy of mixing contributing to passive swelling, and P ion , the osmotic pressure from the chemical and electrochemical charge inside the hydrogel:…”

“…and Östmans et al. [ 17,18 ] In our electroactive nanoparticle gel model (see Supporting Information), P chem is divided into the terms P mix , the free energy of mixing contributing to passive swelling, and P ion , the osmotic pressure from the chemical and electrochemical charge inside the hydrogel: $$$$\begin{equation} {P}_{\mathrm{ion}}=\textit{RT}\left(\frac{{\varphi}_{1}\alpha {Q}_{\mathrm{CNF}}}{V}+\frac{{\varphi}_{2}{Q}_{\mathrm{CNT}}}{V}-{\varphi}_{3}2{c}_{\mathrm{sol}}\right) \end{equation}$$$$where R is the gas constant, T is the absolute temperature, Q is the molar charge associated with the CNFs or CNTs including counterions, α is the degree of dissociation/association of the titrating groups of the CNFs, $${\varphi}_{n}$$ are the osmotic coefficients with the subscript describing different ion‐pairs, V is the volume of the hydrogel, and c sol the molar concentration of the electrolyte multiplied by 2 to account for both ions in the pair. Equation () shows how $${Q}_{\mathrm{CNF}}$$, $${Q}_{\mathrm{CNT}}$$, or $${c}_{\mathrm{sol}}$$ control the osmotic pressure.…”

“…Its state is retained after the electrical potential is turned off because of the stick-slip-stick behavior of nanowire networks. [17,18] The shape-morphing can thus be controlled with high precision, and the degree of expansion can be self-sensed by measuring the varying electronic resistance. [7] These properties make nanowire hydrogels an ideal material for electrotunable membranes for adaptive separation, fractionation, and distribution of, for example, drugs or biomolecules; a unique and innovative membrane technology.…”