Influence of network topology on the swelling of polyelectrolyte nanogels

Abstract

It is well-known that the swelling behavior of ionic nanogels depends on their cross-link density, however it is unclear how different topologies should affect the response of the polyelectrolyte network. Here we perform Monte Carlo simulations to obtain the equilibrium properties of ionic nanogels as a function of salt concentration Cs and the fraction f of ionizable groups in a polyelectrolyte network formed by cross-links of functionality z. Our results indicate that the network with cross-links of low connectivity result in nanogel particles with higher swelling ratios. We also confirm a de-swelling effect of salt on nanogel particles.

Maximizing the absorption of small cosolutes inside neutral hydrogels: steric exclusion versus hydrophobic adhesion

“…An interesting extension of this work would be the study of the influence of the network topology, such as chain polydispersity. [57][58][59] According to Edgecombe and Linse, 57 as the network is made polydisperse, the microgel volume decreases, with the short chains being more stretched and the long ones less stretched as compared to a monodisperse chain length distribution. Based on this, we expect that the leading contribution of considering chain polydispersity is that swollen microgels have a lower volume, and so a corrected packing fraction f m 0 larger than the corresponding one for monodisperse chains.…”

Self-Assembly of Ionic Microgels Driven by an Alternating Electric Field: Theory, Simulations, and Experiments

“…Several inherent properties of nanoparticles such as their size, shape, charge, and degree of polydispersity can be reasonably well controlled during the synthesis mechanisms to render particles a rich variety of interactions and self-assembly properties. ,, Decorating nanoparticles with asymmetric patches, − coating them with different objects, − or grafting polymer chains along their surfaces − are among the usual synthesis protocols adopted to achieve desirable particle effective interactions in the case of hard surfaces. , In soft nanoparticles, the degree of softness and the size/shape deformations under external stress are essential features to control their equilibrium properties with the environment. − Solvent properties such as pH, permittivity, and solvent quality can also have a strong influence on the way suspended nanoparticles interact with one another. − Furthermore, addition of components of smaller length scales such as polymer chains or ionic components provides also a convenient route to properly tune desirable effective interactions. ,− In general, the more sensitive the particles are to such changes in their environmental conditions, the richer the class of mutual interactions and morphological properties that can be artificially induced upon them. In this sense, microgels (or nanogels in a smaller length scale) represent promising candidates for the design of responsive materials with well controllable behavior. ,,,, Contrary to hard nanoparticles, soft microgels are able to change their size and internal conformation in response to external stimuli, the equilibrium properties being mostly dictated by the osmotic flow across their interfaces. − The elastic character of the cross-linked polymer chains allows microgels to deform and partially interpenatrate each other whenever strong attractive forces among them are present. − This also makes it possible to assemble these particles into very compact aggregates or even synthesizing them at local volume fractions that exceed close...…”

From Microscale to Macroscale: Nine Orders of Magnitude for a Comprehensive Modeling of Hydrogels for Controlled Drug Delivery

“…MC simulations attracted a lot of interest for the investigation of polyelectrolyte hydrogels [93,94,95,96]. In a series of works, Edgecombe and Linse [97,98,99] systematically examined the effects of salt, oppositely charged macroions, polymer polydispersity, and network defects on swelling equilibrium.…”