Modelling realistic microgels in an explicit solvent

Camerin, Fabrizio; Gnan, Nicoletta; Rovigatti, Lorenzo; Zaccarelli, Emanuela

doi:10.1038/s41598-018-32642-5

Cited by 45 publications

(58 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[37] This radial gradient in cross-linking density, which usually becomes more significant for weakly cross-linked microgels, is known to affect their equilibrium swelling properties. [107][108][109][110] Experiments by Acciaro et al [100] have established that microgels without a radial cross-linking gradient display R(298 K)/R(θ) values similar (but somewhat higher) to those of heterogeneously crosslinked microgels considered in this study. Further, data for the swelling of macroscopic gels, which do not display a core-shell structure, are in broad agreement with that of microgels, see Figure 8.…”

Section: Possible Reasons For the Observed Discrepanciessupporting

confidence: 62%

“…Microgels synthesized by precipitation polymerization display higher cross‐linking densities around the core region and weaker cross‐linking densities around the outer part of the microgels, where dangling chains are also present . This radial gradient in cross‐linking density, which usually becomes more significant for weakly cross‐linked microgels, is known to affect their equilibrium swelling properties . Experiments by Acciaro et al .…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

The Swelling of Poly(Isopropylacrylamide) Near the θ Temperature: A Comparison between Linear and Cross‐Linked Chains

Lopez

Scotti

Brugnoni

et al. 2018

Macro Chemistry & Physics

View full text Add to dashboard Cite

Thermoresponsive polymeric gels are a class of smart materials with the ability to absorb or release large amounts of solvent when changes in their environment occur. Scaling theories of gel swelling (de Gennes' c∗ theorem and Obukhov's model) predict that the swelling of a gel correlates with that of a linear chain with equal degree of polymerization to that of a network strand. Data on linear and cross‐linked poly(N‐isopropylacrylamide) (PNIPAM) in aqueous solutions of different molar masses under θ temperature and good solvent conditions are examined. The Kuhn length of PNIPAM is evaluated to be LK = 4 ± 1 nm, in strong disagreement with previous estimates by single molecule force spectroscopy. The excluded volume strength (B) varies with the reduced temperature (τ) as B ≃ 4.7τ nm. While the power law exponent for the equilibrium swelling as a function of degree of cross‐linking is close to the scaling predictions, the degree of swelling observed in cross‐linked networks is two to three orders of magnitude larger than that expected from scaling models. The large differences between theoretical predictions and experimental results probably arise from the highly inhomogeneous nature of PNIPAM gels.

show abstract

Section: Possible Reasons For the Observed Discrepanciessupporting

confidence: 62%

Section: Resultsmentioning

confidence: 99%

The Swelling of Poly(Isopropylacrylamide) Near the θ Temperature: A Comparison between Linear and Cross‐Linked Chains

Lopez

Scotti

Brugnoni

et al. 2018

Macro Chemistry & Physics

View full text Add to dashboard Cite

show abstract

“…For example, in the widely used MPCD method, radii of gyration R g ∼ 50 would require using boxes of side L box ∼ 200 and at least 5L 3 box = 4 × 10 7 solvent particles for both correctly implementing the hydrodynamic interactions and avoiding significant finite-size effects [36]. Still, based on previous evidence [37][38][39][40] we do not expect that hydrodynamics will lead to qualitatively different results from those presented here. We used a time step δt = 0.005, and a friction γ = 0.05, which is high enough for good thermalization and low enough to prevent strong damping that would slow down the dynamics to time scales requiring a huge computational cost.…”

Section: Model and Simulation Detailsmentioning

confidence: 62%

Coarsening Kinetics of Complex Macromolecular Architectures in Bad Solvent

Paciolla

Arismendi‐Arrieta²,

Moreno

2019

Preprint

View full text Add to dashboard Cite

This study reports a general scenario for the out-of-equilibrium features of collapsing polymeric architectures. We use molecular dynamics simulations to characterize the coarsening kinetics, in bad solvent, for several macromolecular systems with an increasing degree of structural complexity. In particular, we focus on: flexible and semiflexible polymer chains, star polymers with 3 and 12 arms, and microgels with both ordered and disordered networks.Starting from a powerful analogy with critical phenomena, we construct a density field representation that removes fast fluctuations and provides a consistent characterization of the domain growth. Our results indicate that the coarsening kinetics presents a scaling behaviour that is independent of the solvent quality parameter, in analogy to time-temperature superposition principle. Interestingly, the domain growth in time follows a power-law behaviour that is approximately independent of the architecture for all the flexible systems; while it is steeper for the semiflexible chains. Nevertheless, the fractal nature of the dense regions emerging during the collapse exhibits the same scaling behaviour for all the macromolecules.This suggests that the faster growing length scale in the semiflexible chains originates just from a faster mass diffusion along the chain contour, induced by the local stiffness. The decay of the dynamic correlations displays scaling behavior with the growing length scale of the system, which is a characteristic signature in coarsening phenomena. I. INTRODUCTIONUnderstanding the collapse of, fully polymeric, topologically complex objects in a bad solvent is of broad importance, because of its relevance in the early stages of the protein folding [1,2], and its connections with arresting processes or aging phenomena [3,4]. The thermodynamic and structural properties of the macromolecular collapse in solution, occurring when the quality of the solvent is decreased below a critical value, have been exhaustively investigated over the years [5][6][7][8][9][10], and at equilibrium, the dynamic and static behavior are well known above and below the volume phase transition [11]. Comparatively, a general framework for the non-equilibrium aspects, as the kinetics of the collapse, is still lacking. The development of new experimental setups for small angle X-ray scattering or single-molecule fluorescence spectroscopy allows to monitor the collapse arXiv:1912.03551v1 [cond-mat.soft]

show abstract

“…Indeed, our polymer density profiles correlate very well with the results reported 20 for microgels with fried-egg-like shapes. 28,29,52,57 Even though these simulations correspond to nanogels that are far from the overlap concentration, such deformable objects are intrinsically permeable. This implies that droplet adhesion can be facilitated or inhibited by tunning the invasive capacity of such particles.…”

Section: Solvent Penetration In Deformable Porous Cavitiesmentioning

confidence: 99%

Deformability and solvent penetration in soft nanoparticles at liquid-liquid interfaces

Arismendi‐Arrieta

Moreno

2020

Journal of Colloid and Interface Science

View full text Add to dashboard Cite

Soft nanoparticles hold promise as smart emulsifiers due to their high degree of deformability, permeability and stimuli responsive properties. By means of large-scale simulations we investigate the structural properties of nanogels at liquid-liquid (A-B) interfaces and the miscibility of the liquids inside the nanogels, covering the whole range of interfacial strength from the limit of single-liquid to the case of stiff interfaces. To study the role of the internal architecture and deformability of the nanogel we simulate a realistic disordered and an ideal regular network, for a broad range of cross-linking degrees. Unlike in previous investigations on liquid miscibility, excluded volume interactions are considered for both the monomers and the explicit solvent particles. The nanogel permeability is analysed by using an unbiased grid representation that accounts for the surface fluctuations and adds to the density profiles the exact number of liquid particles inside the nanogel. The better packing efficiency of the regular network leads 1 arXiv:1911.06725v1 [cond-mat.soft] 15 Nov 2019to higher values of the total liquid uptake and the invasive capacity (A-particles in B-side and viceversa) than in the disordered network, though differences vanish in the limit of rigid interfaces. Uptake and invasion are optimized at a cross-linking degree that depends on the interfacial strength, tending to ∼ 15 − 20 for moderate and stiff interfaces. As the interfacial strength increases, the miscibility inside the nanogel is enhanced by a factor of up to 5 with respect to the bare interface, with the disordered networks providing a better mixing than their ideal counterparts. The emerging scenario reported here provides general guidelines for tuning the shape, uptake, invasive, and mixing capacities of nanogels adsorbed at liquid-liquid interfaces.

show abstract

Modelling realistic microgels in an explicit solvent

Cited by 45 publications

References 50 publications

The Swelling of Poly(Isopropylacrylamide) Near the θ Temperature: A Comparison between Linear and Cross‐Linked Chains

The Swelling of Poly(Isopropylacrylamide) Near the θ Temperature: A Comparison between Linear and Cross‐Linked Chains

Coarsening Kinetics of Complex Macromolecular Architectures in Bad Solvent

Deformability and solvent penetration in soft nanoparticles at liquid-liquid interfaces

Contact Info

Product

Resources

About