Crowded solutions of single-chain nanoparticles under shear flow

Formanek, Maud; Moreno, Angel J.

doi:10.1039/d0sm01978j

Cited by 5 publications

(4 citation statements)

References 67 publications

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“…To avoid trivial bonding, the random distribution of reactive monomers along the chain backbone is made with the constraint that any two consecutive reactive monomers are separated by at least one nonreactive monomer. This bond formation is identical to the cross-linking process in the case of irreversibly intramolecularly cross-linked SCNPs employed in previous studies. ,− Once a bond is formed, the two participating monomers interact via a Morse potential with adjustable parameters K and r 0 . In the case of the irreversible cross-linking, if two reactive monomers form a bond, they interact for the rest of the simulation via the same FENE potential (eq ) as the permanent backbone bonds.…”

Section: Simulation Detailsmentioning

confidence: 67%

Gel Formation in Reversibly Cross-Linking Polymers

et al. 2021

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By means of Langevin dynamics simulations, we investigate the gel formation of randomly functionalized polymers in solution, with the ability to form both intra-and intermolecular reversible bonds. Under highly dilute conditions, these polymers form soft nano-objects (so-called single-chain nanoparticles, SCNPs), resulting from the purely intramolecular cross-linking of the reactive functional groups. Here we show that the competition between intra-and intermolecular bonds at finite concentration is governed 1 arXiv:2012.00862v1 [cond-mat.soft] 1 Dec 2020 by a delicate balance of various entropic contributions and leads to a density dependent effective valence. System-spanning networks are formed at relatively low monomer densities and their stability is mediated by just a small number of intermolecular connections per chain. The formation of intermolecular bonds furthermore can induce a non-monotonic dependence of the polymer size on the density for long bond lifetimes.Concomitantly, the polymers in the percolating cluster adopt an intramolecular structure characteristic for self-avoiding chains, which constitutes a strong contrast to the fractal globular behavior of irreversible SCNPs in crowded solutions with purely topological interactions (no intermolecular bonds). Finally, we study the dynamics of the system, which displays signatures expected for reversible gel-forming systems. An interesting behavior emerges in the reorganization dynamics of the percolating cluster. The relaxation is mostly mediated by the diffusion over long distances, through breaking and formation of bonds, of chains that do not leave the percolating cluster. Regarding the few chains that are transiently free, the time they spend until they reattach to the cluster is solely governed by the bond strength.

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Section: Simulation Detailsmentioning

confidence: 67%

Gel Formation in Reversibly Cross-Linking Polymers

et al. 2021

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“…In order to investigate the effects of the shear flow on such systems, one needs to have an approach for modelling the solvent. Among possible techniques [81,94,[99][100][101], we opt for the Lattice-Boltzmann scheme [102,103]. This method simulates the flow of a Newtonian fluid by solving the discrete Boltzmann equation on a lattice, which corresponds to the Navier-Stokes equations in the limit of small Mach numbers.…”

Section: Simulation Protocolmentioning

confidence: 99%

“…The majority of micro-and nanogel applications rely on the rheology of their diluted or concentrated suspensions. Thus, the behaviour of nonmagnetic nano-and microgels in the flow was actively studied in the last years revealing the ability of the flow to change structure and mechanics of these systems [90][91][92][93][94] opening up new challenges in the field. Even less understood is the rheology of magnetic nanogles [50].…”

Section: Introductionmentioning

confidence: 99%

Behaviour of a magnetic nanogel in a shear flow

Novikau¹,

Novak²,

Pyanzina³

et al. 2021

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Magnetic nanogels (MNG) -soft colloids made of polymer matrix with embedded in it magnetic nanoparticles (MNPs)are promising magneto-controllable drug carriers. In order to develop this potential, one needs to clearly understand the relationship between nanogel magnetic properties and its behaviour in a hydrodynamic flow. Considering the size of the MNG and typical time and velocity scales involved in their nanofluidics, experimental characterisation of the system is challenging. In this work, we perform molecular dynamics (MD) simulations combined with the Lattice-Boltzmann (LB) scheme aiming at describing the impact of the shear rate ( γ) on the shape, magnetic structure and motion of an MNG. We find that in a shear flow the centre of mass of a MNG tends to be in the centre of a channel and to move preserving the distance to both walls. The MNG monomers along with translation are involved in two more types of motion, they rotate around the centre of mass and oscillate with respect to the latter. It results in synchronised tumbling and wobbling of the whole MNG accompanied by its volume oscillates. The fact the a MNG is a highly compressible and permeable for the carrier liquid object makes its behaviour different from that predicted by classical Taylor-type models. We show that the frequency of volume oscillations and rotations are identical and are growing function of the shear rate. We find that the stronger magnetic interactions in the MNG are, the higher is the frequency of this complex oscillatory motion, and the lower is its amplitude. Finally, we show that the oscillations of the volume lead to the periodic changes in MNG magnetic energy.

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“…In addition to conventional experimental approaches used to study nanogels directly in a laboratory where they are synthesised, nowadays we can also rely on computer simulations to study the properties of nanogels 6,[64][65][66][67][68][69][70][71][72][73][74] . Most of these works take as a basis a bead-spring model 75 to model polymer chains.…”

Section: Introductionmentioning

confidence: 99%