Modeling Microgels with a Controlled Structure across the Volume Phase Transition

Ninarello, Andrea; Crassous, Jérôme J.; Paloli, Divya; Camerin, Fabrizio; Gnan, Nicoletta; Rovigatti, Lorenzo; Schurtenberger, Peter; Zaccarelli, Emanuela

doi:10.1021/acs.macromol.9b01122

Cited by 69 publications

(163 citation statements)

References 53 publications

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“…25 In order to go beyond mean-field and to account in a more realistic way for the effect of the network topology, in this work we perform extensive simulations of charged microgels modelled as disordered networks. We start by preparing neutral microgel configurations following previous works, 38,39 ensuring that the internal microgel structure reproduces the swelling behavior and form factors of experimental non-ionic microgels. Then, we add a quenched charge distribution, varying the fraction of charged monomers that are randomly distributed throughout the network.…”

Section: Introductionmentioning

confidence: 99%

“…We simulate microgels in swollen conditions and across the volume phase transition by using a solvophobic interaction between the monomers that models the different quality of the solvent as temperature varies. 38,39 Our work is important to understand the effects that inhomogeneous topologies and charge distributions beyond mean-field can have on the single-particle behavior of ionic microgels, filling a gap in the current literature. In addition, we provide significant insights on the difference between neutral and charged microgels across the volume phase transition.…”

Section: Introductionmentioning

confidence: 99%

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Numerical insights on ionic microgels: structure and swelling behaviour

et al. 2019

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Recent progress has been made in the numerical modelling of neutral microgel particles with a realistic, disordered structure. In this work we extend this approach to the case of co-polymerised microgels where a thermoresponsive polymer is mixed with acidic groups. We compare the cases where counterions directly interact with microgel charges or are modelled implicitly through a Debye-Hückel description. We do so by performing extensive numerical simulations of single microgels across the volume phase transition varying the temperature and the fraction of charged monomers. We find that the presence of charges considerably alters the microgel structure, quantified by the monomer density profiles and by the form factors of the microgels, particularly close to the volume phase transition (VPT). We observe significant deviations between the implicit and explicit models, with the latter comparing more favourably to available experiments. In particular, we observe a shift of the VPT temperature to larger values as the amount of charged monomers increases. We also find that below the VPT the microgel-counterion complex is almost neutral, while it develops a net charge above the VPT. Interestingly, under these conditions the collapsed microgel still retains a large amount of counterions inside its structure. Since these interesting features cannot be captured by the implicit model, our results show that it is crucial to explicitly include the counterions in order to realistically model ionic thermoresponsive microgels.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical insights on ionic microgels: structure and swelling behaviour

et al. 2019

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“…It is our intention to apply this approach to the study of other polymeric systems, such as microgels, 42,43 for which accurate monomer density profiles have recently been calculated at different solvophobic conditions. 44 Furthermore, this method opens up the possibility to go beyond single-particle studies and to address the dynamics of polymeric objects at finite concentrations. One straightforward extension would be to study star polymers with a large number of arms and to address their phase behavior.…”

Section: Discussionmentioning

confidence: 99%

Multi-particle collision dynamics for a coarse-grained model of soft colloids

Ruiz-Franco

Jaramillo-Cano

Camargo

et al. 2019

The Journal of Chemical Physics

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The growing interest in the dynamical properties of colloidal suspensions, both in equilibrium and under an external drive such as shear or pressure flow, requires the development of accurate methods to correctly include hydrodynamic effects due to the suspension in a solvent. In the present work, we generalize Multi-Particle Collision Dynamics (MPCD) to be able to deal with soft, polymeric colloids. Our methods build on the knowledge of the monomer density profile that can be obtained from monomer-resolved simulations without hydrodynamics or from theoretical arguments. We hereby propose two different approaches. The first one simply extends the MPCD method by including in the simulations effective monomers with a given density profile, thus neglecting monomer-monomer interactions. The second one considers the macromolecule as a single penetrable soft colloid (PSC), which is permeated by an inhomogeneous distribution of solvent particles. By defining an appropriate set of rules to control the collision events between the solvent and the soft colloid, both linear and angular momenta are exchanged. We apply these methods to the case of linear chains and star polymers for varying monomer lengths and arm number, respectively, and compare the results for the dynamical properties with those obtained within monomer-resolved simulations. We find that the effective monomer method works well for linear chains, while the PSC method provides very good results for stars. These methods pave the way to extend MPCD treatments to complex macromolecular objects such as microgels or dendrimers and to work with soft colloids at finite concentrations.

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“…One of the standard methods to investigate the internal structure of soft matter is to perform small angle light, X-ray or neutron scattering [70][71][72][73][74][75][76][77][78]. In case of a spatially isotropic system, the scattering intensity can be converted into a centre-centre structure factor (SF) S :…”

Section: Impact Of An Applied Field On the Structural Propertiesmentioning

confidence: 99%

The influence of an applied magnetic field on the self-assembly of magnetic nanogels

Novikau

Sánchez

Kantorovich

2020

Journal of Molecular Liquids

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Using Langevin dynamics simulations, we investigate the self-assembly of magnetic nanogels in the presence of applied magnetic fields of moderate strength. We find that even weak fields lead to drastic changes in the structure factors of both, the embedded magnetic nanoparticles and of whole nanogel particles. Nanogels assemble by uniting magnetic particle clusters forming inter-gel bridges. At zero field the average amount of such bridges for a pair of nanogels is close to one, whereas even for weak fields it fastly doubles. Rapid growth of cluster size at low values of the applied field is followed by a broad region of slow increase, caused by the mechanical constraints imposed the polymer matrix. The influence of the latter manifests itself in both, the slow growth of the magnetisation curve at intermediate fields and the slow decay of the total Zeeman energy.

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Modeling Microgels with a Controlled Structure across the Volume Phase Transition

Cited by 69 publications

References 53 publications

Numerical insights on ionic microgels: structure and swelling behaviour

Numerical insights on ionic microgels: structure and swelling behaviour

Multi-particle collision dynamics for a coarse-grained model of soft colloids

The influence of an applied magnetic field on the self-assembly of magnetic nanogels

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