1
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Funkenbusch WT, Silmore KS, Doyle PS. Shear annealing of a self-interacting sheet. SOFT MATTER 2024; 20:6952-6964. [PMID: 39169795 DOI: 10.1039/d4sm00710g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/23/2024]
Abstract
2D materials such as graphene, graphene oxide, transition metal dichalcogenides, and 2D polymers have unique properties which allow them to be used in many applications from electronics to energy to biotechnology. Producing and applying these materials often involves solution processing. Previous computational studies have observed 2D sheets in shear and extensional flows, but have focused on steady flows, even though the dynamics of these materials might exhibit hysteresis. In this work, we study 2D sheets with short-ranged attractive interactions under time-varying shear. We show that, even with relatively simple protocols, the properties of sheet suspensions can be tuned.
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Affiliation(s)
- William T Funkenbusch
- Department of Chemical Engineering, Massachusetts Institute of Technology, 25 Ames St, Cambridge, MA, 02139, USA.
| | - Kevin S Silmore
- Department of Chemical Engineering, Massachusetts Institute of Technology, 25 Ames St, Cambridge, MA, 02139, USA.
| | - Patrick S Doyle
- Department of Chemical Engineering, Massachusetts Institute of Technology, 25 Ames St, Cambridge, MA, 02139, USA.
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2
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Funkenbusch WT, Silmore KS, Doyle PS. Dynamics of a self-interacting sheet in shear flow. SOFT MATTER 2024; 20:4474-4487. [PMID: 38787762 DOI: 10.1039/d4sm00197d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2024]
Abstract
Solution processing of 2D materials such as graphene is important for applications thereof, yet a complete fundamental understanding of how 2D materials behave dynamically in solution is lacking. Here, we extend previous work by Silmore et al., Soft Matter, 2021, 17(18), 4707-4718 by adding short-ranged Lennard-Jones interactions to 2D sheets in shear flow. We find that the addition of these interactions allows for a rich landscape of conformations which depend on the balance between shear strength, bending rigidity, and interaction strength as well as the initial configuration of the sheet. We explore this conformational space and classify sheets as flat, tumbling, 1D folded, or 2D folded based on their conformational properties. We use kinetic and energetic arguments to explain why sheets adopt certain conformations within the folded regime. Finally, we calculate the stresslet and find that, even in the absence of thermal fluctuations and multiple sheet interactions, shear-thinning followed by shear-thickening behavior can appear.
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Affiliation(s)
- William T Funkenbusch
- Massachusetts Institute of Technology Department of Chemical Engineering, 25 Ames St, Cambridge MA, 02139, USA.
| | - Kevin S Silmore
- Massachusetts Institute of Technology Department of Chemical Engineering, 25 Ames St, Cambridge MA, 02139, USA.
| | - Patrick S Doyle
- Massachusetts Institute of Technology Department of Chemical Engineering, 25 Ames St, Cambridge MA, 02139, USA.
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3
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Mariya S, Barr JJ, Sunthar P, Prakash JR. Universal scaling of the diffusivity of dendrimers in a semidilute solution of linear polymers. SOFT MATTER 2024; 20:993-1008. [PMID: 38197233 DOI: 10.1039/d3sm01190a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2024]
Abstract
The static and dynamic properties of dendrimers in semidilute solutions of linear chains of comparable size are investigated using Brownian dynamics simulations. The radius of gyration and diffusivity of a wide variety of low generation dendrimers and linear chains in solution follow universal scaling laws independent of their topology. Analysis of the shape functions and internal density of dendrimers shows that they are more spherical than linear chains and have a dense core. At intermediate times, dendrimers become subdiffusive, with an exponent higher than that previously reported for nanoparticles in semidilute polymer solutions. The long-time diffusivity of dendrimers does not follow theoretical predictions for nanoparticles. We propose a new scaling law for the long-time diffusion coefficients of dendrimers which accounts for the fact that, unlike nanoparticles, dendrimers shrink with an increase in background solution concentration. Analysis of the properties of a special case of a higher functionality dendrimer shows a transition from polymer-like to nanoparticle-like behaviour.
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Affiliation(s)
- Silpa Mariya
- IITB-Monash Research Academy, Indian Institute of Technology Bombay, Mumbai, 400076, India
| | - Jeremy J Barr
- School of Biological Sciences, Monash University, Clayton, VIC 3800, Australia
| | - P Sunthar
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, 400076, India
| | - J Ravi Prakash
- Department of Chemical and Biological Engineering, Monash University, Clayton, VIC 3800, Australia.
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4
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Torre KW, de Graaf J. Hydrodynamic lubrication in colloidal gels. SOFT MATTER 2023; 19:7388-7398. [PMID: 37740405 PMCID: PMC10548787 DOI: 10.1039/d3sm00784g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 09/15/2023] [Indexed: 09/24/2023]
Abstract
Colloidal gels are elasto-plastic materials composed of an out-of-equilibrium, self-assembled network of micron-sized (solid) particles suspended in a fluid. Recent work has shown that far-field hydrodynamic interactions do not change gel structure, only the rate at which the network forms and ages. However, during gel formation, the interplay between short-ranged attractions leading to gelation and equally short-ranged hydrodynamic lubrication interactions remains poorly understood. Here, we therefore study gelation using a range of hydrodynamic descriptions: from single-body (Brownian Dynamics), to pairwise (Rotne-Prager-Yamakawa), to (non-)lubrication-corrected many-body (Stokesian Dynamics). We confirm the current understanding informed by simulations accurate in the far-field. Yet, we find that accounting for lubrication can strongly impact structure at low colloid volume fraction. Counterintuitively, strongly dissipative lubrication interactions also accelerate the aging of a gel, irrespective of colloid volume fraction. Both elements can be explained by lubrication forces facilitating collective dynamics and therefore phase-separation. Our findings indicate that despite the computational cost, lubricated hydrodynamic modeling with many-body far-field interactions is needed to accurately capture the evolution of the gel structure.
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Affiliation(s)
- K W Torre
- Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands.
| | - J de Graaf
- Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands.
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5
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Hashemi A, Peláez RP, Natesh S, Sprinkle B, Maxian O, Gan Z, Donev A. Computing hydrodynamic interactions in confined doubly periodic geometries in linear time. J Chem Phys 2023; 158:2882262. [PMID: 37094003 DOI: 10.1063/5.0141371] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 03/20/2023] [Indexed: 04/26/2023] Open
Abstract
We develop a linearly scaling variant of the force coupling method [K. Yeo and M. R. Maxey, J. Fluid Mech. 649, 205-231 (2010)] for computing hydrodynamic interactions among particles confined to a doubly periodic geometry with either a single bottom wall or two walls (slit channel) in the aperiodic direction. Our spectrally accurate Stokes solver uses the fast Fourier transform in the periodic xy plane and Chebyshev polynomials in the aperiodic z direction normal to the wall(s). We decompose the problem into two problems. The first is a doubly periodic subproblem in the presence of particles (source terms) with free-space boundary conditions in the z direction, which we solve by borrowing ideas from a recent method for rapid evaluation of electrostatic interactions in doubly periodic geometries [Maxian et al., J. Chem. Phys. 154, 204107 (2021)]. The second is a correction subproblem to impose the boundary conditions on the wall(s). Instead of the traditional Gaussian kernel, we use the exponential of a semicircle kernel to model the source terms (body force) due to the presence of particles and provide optimum values for the kernel parameters that ensure a given hydrodynamic radius with at least two digits of accuracy and rotational and translational invariance. The computation time of our solver, which is implemented in graphical processing units, scales linearly with the number of particles, and allows computations with about a million particles in less than a second for a sedimented layer of colloidal microrollers. We find that in a slit channel, a driven dense suspension of microrollers maintains the same two-layer structure as above a single wall, but moves at a substantially lower collective speed due to increased confinement.
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Affiliation(s)
- Aref Hashemi
- Courant Institute, New York University, New York, New York 10012, USA
| | - Raúl P Peláez
- Courant Institute, New York University, New York, New York 10012, USA
- Departamento Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, Spain
| | - Sachin Natesh
- Courant Institute, New York University, New York, New York 10012, USA
- Department of Applied Mathematics, University of Colorado Boulder, Boulder, Colorado 80309, USA
| | - Brennan Sprinkle
- Courant Institute, New York University, New York, New York 10012, USA
- Department of Applied Mathematics and Statistics, Colorado School of Mines, Golden, Colorado 80401, USA
| | - Ondrej Maxian
- Courant Institute, New York University, New York, New York 10012, USA
| | - Zecheng Gan
- Courant Institute, New York University, New York, New York 10012, USA
- Department of Mathematics, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Aleksandar Donev
- Courant Institute, New York University, New York, New York 10012, USA
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6
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Sherman ZM, Kim K, Kang J, Roman BJ, Crory HSN, Conrad DL, Valenzuela SA, Lin E, Dominguez MN, Gibbs SL, Anslyn EV, Milliron DJ, Truskett TM. Plasmonic Response of Complex Nanoparticle Assemblies. NANO LETTERS 2023; 23:3030-3037. [PMID: 36989531 DOI: 10.1021/acs.nanolett.3c00429] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Optical properties of nanoparticle assemblies reflect distinctive characteristics of their building blocks and spatial organization, giving rise to emergent phenomena. Integrated experimental and computational studies have established design principles connecting the structure to properties for assembled clusters and superlattices. However, conventional electromagnetic simulations are too computationally expensive to treat more complex assemblies. Here we establish a fast, materials agnostic method to simulate the optical response of large nanoparticle assemblies incorporating both structural and compositional complexity. This many-bodied, mutual polarization method resolves limitations of established approaches, achieving rapid, accurate convergence for configurations including thousands of nanoparticles, with some overlapping. We demonstrate these capabilities by reproducing experimental trends and uncovering far- and near-field mechanisms governing the optical response of plasmonic semiconductor nanocrystal assemblies including structurally complex gel networks and compositionally complex mixed binary superlattices. This broadly applicable framework will facilitate the design of complex, hierarchically structured, and dynamic assemblies for desired optical characteristics.
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Affiliation(s)
- Zachary M Sherman
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, 78712, Texas United States
| | - Kihoon Kim
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, 78712, Texas United States
| | - Jiho Kang
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, 78712, Texas United States
| | - Benjamin J Roman
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, 78712, Texas United States
| | - Hannah S N Crory
- Department of Chemistry, University of Texas at Austin, Austin, 78712, Texas United States
| | - Diana L Conrad
- Department of Chemistry, University of Texas at Austin, Austin, 78712, Texas United States
| | - Stephanie A Valenzuela
- Department of Chemistry, University of Texas at Austin, Austin, 78712, Texas United States
| | - Emily Lin
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, 78712, Texas United States
| | - Manuel N Dominguez
- Department of Chemistry, University of Texas at Austin, Austin, 78712, Texas United States
| | - Stephen L Gibbs
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, 78712, Texas United States
| | - Eric V Anslyn
- Department of Chemistry, University of Texas at Austin, Austin, 78712, Texas United States
| | - Delia J Milliron
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, 78712, Texas United States
- Department of Chemistry, University of Texas at Austin, Austin, 78712, Texas United States
| | - Thomas M Truskett
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, 78712, Texas United States
- Department of Physics, University of Texas at Austin, Austin, 78712, Texas United States
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7
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Torre KW, de Graaf J. Structuring colloidal gels via micro-bubble oscillations. SOFT MATTER 2023; 19:2771-2779. [PMID: 36988352 PMCID: PMC10091832 DOI: 10.1039/d2sm01450e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 03/09/2023] [Indexed: 06/19/2023]
Abstract
Locally (re)structuring colloidal gels - micron-sized particles forming a connected network with arrested dynamics - can enable precise tuning of the micromechanical and -rheological properties of the system. A recent experimental study [B. Saint-Michel, G. Petekidis, and V. Garbin, Soft Matter, 2022, 18, 2092] showed that local ordering can be rapidly induced by acoustically modulating an embedded microbubble. Here, we perform Brownian dynamics simulations to understand the mechanical effect of an oscillating microbubble on the next-to-bubble structure of the embedding colloidal gel. Our simulations reveal hexagonal-close-packed structures over a range that is comparable to the amplitude of the oscillations. However, we were unable to reproduce the unexpectedly long-ranged modification of the gel structure - dozens of amplitudes - observed in experiment. This suggests including long-ranged effects, such as fluid flow, should be considered in future computational work.
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Affiliation(s)
- K W Torre
- Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands.
| | - J de Graaf
- Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands.
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8
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Lorenzo T, Marco L. Brownian dynamics simulations of shear-induced aggregation of charged colloidal particles in the presence of hydrodynamic interactions. J Colloid Interface Sci 2022; 624:637-649. [PMID: 35696787 DOI: 10.1016/j.jcis.2022.05.047] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 05/06/2022] [Accepted: 05/07/2022] [Indexed: 11/16/2022]
Abstract
HYPOTHESIS In spite of the abundant literature on Brownian simulations of the aggregation behavior of colloidal suspensions both under quiescent conditions and in the presence of shear, few works performed simulations including the effect of hydrodynamic interactions. Even fewer works have investigated the effects of shear on the aggregation of electrostatically-stabilized colloidal suspensions. SIMULATIONS In this work, we employed Brownian dynamics simulations implementing the Rotne-Prager-Yamakawa approximation to account for hydrodynamic interactions and investigated the aggregation kinetics of electrostatically-stabilized colloidal suspensions exposed to simple shear, for various Péclet number values, particle volume fractions and surface potential values. RESULTS The increase in Péclet number (i.e., in the shear rate), leads to an overall increase in the aggregation rate and the formation of large aggregates that, for sufficiently high volume fractions, rapidly grow, leading to either breakup and restructuring phenomena or percolation of the system. In some cases, a bimodal distribution of the cluster population was observed. Our simulations further indicate that at the highest Péclet, the aggregation dynamics is independent of the energy barrier and entirely controlled by shear. A comparison with a simple BD method reveals that neglecting long-range hydrodynamic interactions leads to a substantial underestimation of the aggregation rate.
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Affiliation(s)
- Turetta Lorenzo
- University of Fribourg, Department of Chemistry, Chemin du Musée 9, CH-1700 Fribourg, Switzerland
| | - Lattuada Marco
- University of Fribourg, Department of Chemistry, Chemin du Musée 9, CH-1700 Fribourg, Switzerland.
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9
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Alcázar-Cano N, Delgado-Buscalioni R. Hydrodynamics induce superdiffusive jumps of passive tracers along critical paths of random networks and colloidal gels. SOFT MATTER 2022; 18:1941-1954. [PMID: 35191454 DOI: 10.1039/d1sm01713f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We present a numerical study on the effect of hydrodynamic interactions (HI) on the diffusion of inert point tracer particles in several fixed random structures. As expected, the diffusion is hampered by the extra hydrodynamic friction introduced by the obstacle network. However, a non-trivial effect due to HI appears in the analysis of the van-Hove displacement probability close to the percolation threshold, where tracers diffuse through critical fractal paths. We show that the tracer dynamics can be split up into short and long jumps, the latter being ruled by either exponential or Gaussian van Hove distribution tails. While at short time HI slow down the tracer diffusion, at long times, hydrodynamic interactions with the obstacles increase the probability of longer jumps, which circumvent the traps of the labyrinth more easily. Notably, the relation between the anomalous diffusion exponent and the fractal dimension of the critical (intricate) paths is greater than one, which implies that the long-time (long-jump) diffusion is mildly superdiffuse. A possible reason for such a hastening of the diffusion along the network corridors is the hydrodynamically induced mobility anisotropy, which favours displacements parallel to the walls, an effect which has already been experimentally observed in collagen gels.
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Affiliation(s)
- Nerea Alcázar-Cano
- Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid and Condensed Matter Physics Center (IFIMAC), Madrid, Spain.
| | - Rafael Delgado-Buscalioni
- Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid and Condensed Matter Physics Center (IFIMAC), Madrid, Spain.
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10
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Turetta L, Lattuada M. The role of hydrodynamic interactions on the aggregation kinetics of sedimenting colloidal particles. SOFT MATTER 2022; 18:1715-1730. [PMID: 35147636 DOI: 10.1039/d1sm01637g] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The aggregation kinetics of sedimenting colloidal particles under fully destabilized conditions has been investigated over a wide range of particle volume fractions (Φ) and Péclet numbers (Pe) using the recent PSE algorithm implementing the Rotne-Prager-Yamakawa (RPY) approximation for long-range Hydrodynamic Interactions (HI). Fast Lubrication Dynamics (FLD) and simple Brownian Dynamics (BD) methods have also been employed to assess the importance of long range hydrodynamic interactions on the resulting dynamics. It has been observed that long-range hydrodynamic interactions are essential to capture the fast aggregation rates induced by the increase in sedimentation rate of clusters with increasing mass, which manifests with an explosive-like cluster growth after a given induction time. On the contrary, simulations employing only short-range hydrodynamic interactions (such as FLD) and BD (which neglects completely hydrodynamic interactions) are incapable of predicting this very rapid kinetics, because sedimentation simply leads to all particles and clusters moving vertically with identical velocity. It has been observed that at high volume fractions and low Pe values, a gel point can be formed and a phase diagram predicting when gelation is reached has been obtained. It was also observed that, as Pe increases, the anisotropy of the resulting clusters decreases, suggesting that denser clusters with spherical-like morphology are formed due to cluster breakage and restructuring. We can conclude that long-range hydrodynamic effects are of crucial importance in understanding the aggregation dynamics of settling clusters, revealing important features of the complex interplay between sedimentation, and colloidal interactions.
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Affiliation(s)
- Lorenzo Turetta
- Department of Chemistry, University of Fribourg, Chemin du Musée 9, 1700 Fribourg, Switzerland.
| | - Marco Lattuada
- Department of Chemistry, University of Fribourg, Chemin du Musée 9, 1700 Fribourg, Switzerland.
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11
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Silmore KS, Strano MS, Swan JW. Thermally fluctuating, semiflexible sheets in simple shear flow. SOFT MATTER 2022; 18:768-782. [PMID: 34985479 DOI: 10.1039/d1sm01510a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We perform Brownian dynamics simulations of semiflexible colloidal sheets with hydrodynamic interactions and thermal fluctuations in shear flow. As a function of the ratio of bending rigidity to shear energy (a dimensionless quantity we denote S) and the ratio of bending rigidity to thermal energy, we observe a dynamical transition from stochastic flipping to crumpling and continuous tumbling. This dynamical transition is broadened by thermal fluctuations, and the value of S at which it occurs is consistent with the onset of chaotic dynamics found for athermal sheets. The effects of different dynamical conformations on rheological properties such as viscosity and normal stress differences are also quantified. Namely, the viscosity in a dilute dispersion of sheets is found to decrease with increasing shear rate (shear-thinning) up until the dynamical crumpling transition, at which point it increases again (shear-thickening), and non-zero first normal stress differences are found that exhibit a local maximum with respect to temperature at large S (small shear rate). These results shed light on the dynamical behavior of fluctuating 2D materials dispersed in fluids and should greatly inform the design of associated solution processing methods.
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Affiliation(s)
- Kevin S Silmore
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
| | - Michael S Strano
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
| | - James W Swan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
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12
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Wani YM, Kovakas PG, Nikoubashman A, Howard MP. Diffusion and sedimentation in colloidal suspensions using multiparticle collision dynamics with a discrete particle model. J Chem Phys 2022; 156:024901. [PMID: 35032985 DOI: 10.1063/5.0075002] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We study self-diffusion and sedimentation in colloidal suspensions of nearly hard spheres using the multiparticle collision dynamics simulation method for the solvent with a discrete mesh model for the colloidal particles (MD+MPCD). We cover colloid volume fractions from 0.01 to 0.40 and compare the MD+MPCD simulations to experimental data and Brownian dynamics simulations with free-draining hydrodynamics (BD) as well as pairwise far-field hydrodynamics described using the Rotne-Prager-Yamakawa mobility tensor (BD+RPY). The dynamics in MD+MPCD suggest that the colloidal particles are only partially coupled to the solvent at short times. However, the long-time self-diffusion coefficient in MD+MPCD is comparable to that in experiments, and the sedimentation coefficient in MD+MPCD is in good agreement with that in experiments and BD+RPY, suggesting that MD+MPCD gives a reasonable description of hydrodynamic interactions in colloidal suspensions. The discrete-particle MD+MPCD approach is convenient and readily extended to more complex shapes, and we determine the long-time self-diffusion coefficient in suspensions of nearly hard cubes to demonstrate its generality.
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Affiliation(s)
- Yashraj M Wani
- Institute of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | | | - Arash Nikoubashman
- Institute of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | - Michael P Howard
- Department of Chemical Engineering, Auburn University, Auburn, Alabama 36849, USA
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13
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Maxian O, Peláez RP, Mogilner A, Donev A. Simulations of dynamically cross-linked actin networks: Morphology, rheology, and hydrodynamic interactions. PLoS Comput Biol 2021; 17:e1009240. [PMID: 34871298 PMCID: PMC8675935 DOI: 10.1371/journal.pcbi.1009240] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 12/16/2021] [Accepted: 11/12/2021] [Indexed: 12/16/2022] Open
Abstract
Cross-linked actin networks are the primary component of the cell cytoskeleton and have been the subject of numerous experimental and modeling studies. While these studies have demonstrated that the networks are viscoelastic materials, evolving from elastic solids on short timescales to viscous fluids on long ones, questions remain about the duration of each asymptotic regime, the role of the surrounding fluid, and the behavior of the networks on intermediate timescales. Here we perform detailed simulations of passively cross-linked non-Brownian actin networks to quantify the principal timescales involved in the elastoviscous behavior, study the role of nonlocal hydrodynamic interactions, and parameterize continuum models from discrete stochastic simulations. To do this, we extend our recent computational framework for semiflexible filament suspensions, which is based on nonlocal slender body theory, to actin networks with dynamic cross linkers and finite filament lifetime. We introduce a model where the cross linkers are elastic springs with sticky ends stochastically binding to and unbinding from the elastic filaments, which randomly turn over at a characteristic rate. We show that, depending on the parameters, the network evolves to a steady state morphology that is either an isotropic actin mesh or a mesh with embedded actin bundles. For different degrees of bundling, we numerically apply small-amplitude oscillatory shear deformation to extract three timescales from networks of hundreds of filaments and cross linkers. We analyze the dependence of these timescales, which range from the order of hundredths of a second to the actin turnover time of several seconds, on the dynamic nature of the links, solvent viscosity, and filament bending stiffness. We show that the network is mostly elastic on the short time scale, with the elasticity coming mainly from the cross links, and viscous on the long time scale, with the effective viscosity originating primarily from stretching and breaking of the cross links. We show that the influence of nonlocal hydrodynamic interactions depends on the network morphology: for homogeneous meshworks, nonlocal hydrodynamics gives only a small correction to the viscous behavior, but for bundled networks it both hinders the formation of bundles and significantly lowers the resistance to shear once bundles are formed. We use our results to construct three-timescale generalized Maxwell models of the networks.
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Affiliation(s)
- Ondrej Maxian
- Courant Institute, New York University, New York, New York, United States of America
| | - Raúl P Peláez
- Department of Theoretical Condensed Matter Physics, Universidad Autónoma de Madrid, Madrid, Spain
| | - Alex Mogilner
- Courant Institute, New York University, New York, New York, United States of America.,Department of Biology, New York University, New York, New York, United States of America
| | - Aleksandar Donev
- Courant Institute, New York University, New York, New York, United States of America
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14
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Maxian O, Peláez RP, Greengard L, Donev A. A fast spectral method for electrostatics in doubly periodic slit channels. J Chem Phys 2021; 154:204107. [PMID: 34241178 DOI: 10.1063/5.0044677] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We develop a fast method for computing the electrostatic energy and forces for a collection of charges in doubly periodic slabs with jumps in the dielectric permittivity at the slab boundaries. Our method achieves spectral accuracy by using Ewald splitting to replace the original Poisson equation for nearly singular sources with a smooth far-field Poisson equation, combined with a localized near-field correction. Unlike existing spectral Ewald methods, which make use of the Fourier transform in the aperiodic direction, we recast the problem as a two-point boundary value problem in the aperiodic direction for each transverse Fourier mode for which exact analytic boundary conditions are available. We solve each of these boundary value problems using a fast, well-conditioned Chebyshev method. In the presence of dielectric jumps, combining Ewald splitting with the classical method of images results in smoothed charge distributions, which overlap the dielectric boundaries themselves. We show how to preserve the spectral accuracy in this case through the use of a harmonic correction, which involves solving a simple Laplace equation with smooth boundary data. We implement our method on graphical processing units and combine our doubly periodic Poisson solver with Brownian dynamics to study the equilibrium structure of double layers in binary electrolytes confined by dielectric boundaries. Consistent with prior studies, we find strong charge depletion near the interfaces due to repulsive interactions with image charges, which points to the need for incorporating polarization effects in understanding confined electrolytes, both theoretically and computationally.
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Affiliation(s)
- Ondrej Maxian
- Courant Institute, New York University, New York, New York 10012, USA
| | - Raúl P Peláez
- Department of Theoretical Condensed Matter Physics, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Leslie Greengard
- Courant Institute, New York University, New York, New York 10012, USA
| | - Aleksandar Donev
- Courant Institute, New York University, New York, New York 10012, USA
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15
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Silmore KS, Strano MS, Swan JW. Buckling, crumpling, and tumbling of semiflexible sheets in simple shear flow. SOFT MATTER 2021; 17:4707-4718. [PMID: 33978658 DOI: 10.1039/d0sm02184a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
As 2D materials such as graphene, transition metal dichalcogenides, and 2D polymers become more prevalent, solution processing and colloidal-state properties are being exploited to create advanced and functional materials. However, our understanding of the fundamental behavior of 2D sheets and membranes in fluid flow is still lacking. In this work, we perform numerical simulations of athermal semiflexible sheets with hydrodynamic interactions in shear flow. For sheets initially oriented near the flow-vorticity plane, we find buckling instabilities of different mode numbers that vary with bending stiffness and can be understood with a quasi-static model of elasticity. For different initial orientations, chaotic tumbling trajectories are observed. Notably, we find that sheets fold or crumple before tumbling but do not stretch again upon applying greater shear.
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Affiliation(s)
- Kevin S Silmore
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Michael S Strano
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - James W Swan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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16
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Lai PK, Swan JW, Trout BL. Calculation of therapeutic antibody viscosity with coarse-grained models, hydrodynamic calculations and machine learning-based parameters. MAbs 2021; 13:1907882. [PMID: 33834944 PMCID: PMC8043186 DOI: 10.1080/19420862.2021.1907882] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
High viscosity presents a challenge for manufacturing and drug delivery of therapeutic antibodies. The viscosity is determined by protein-protein interactions among many antibodies. Molecular simulation is a promising method to study protein-protein interactions; however, all-atom models do not allow the simulation of multiple molecules, which is necessary to compute viscosity directly. Coarse-grained models, on the other hand can do this. In this work, a 12-bead coarse-grained model based on Swan and coworkers (J. Phys. Chem. B 2018, 122, 2867-2880) was applied to study antibody interactions. Two adjustable parameters related to the short-range interactions on the variable and constant regions were determined by fitting experimental data of 20 IgG1 monoclonal antibodies at 150 mg/mL. The root-mean-square deviation improved from 1 to 0.68, and the correlation coefficient improved from 0.63 to 0.87 compared to that of a previous model that assumed the short-range interactions were the same for all the beads. Our model is also able to calculate the viscosity over a wide range of concentrations without additional parameters. A tabulated viscosity based on our model is provided to facilitate antibody screening in early-stage design.
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Affiliation(s)
- Pin-Kuang Lai
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - James W Swan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Bernhardt L Trout
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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17
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Cichocki B, Szymczak P, Żuk PJ. Generalized Rotne-Prager-Yamakawa approximation for Brownian dynamics in shear flow in bounded, unbounded, and periodic domains. J Chem Phys 2021; 154:124905. [PMID: 33810690 DOI: 10.1063/5.0030175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Inclusion of hydrodynamic interactions is essential for a quantitatively accurate Brownian dynamics simulation of colloidal suspensions or polymer solutions. We use the generalized Rotne-Prager-Yamakawa (GRPY) approximation, which takes into account all long-ranged terms in the hydrodynamic interactions, to derive the complete set of hydrodynamic matrices in different geometries: unbounded space, periodic boundary conditions of Lees-Edwards type, and vicinity of a free surface. The construction is carried out both for non-overlapping as well as for overlapping particles. We include the dipolar degrees of freedom, which allows one to use this formalism to simulate the dynamics of suspensions in a shear flow and to study the evolution of their rheological properties. Finally, we provide an open-source numerical package, which implements the GRPY algorithm in Lees-Edwards periodic boundary conditions.
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Affiliation(s)
- Bogdan Cichocki
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
| | - Piotr Szymczak
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
| | - Paweł J Żuk
- Department of Biosystems and Soft Matter, Institute of Fundamental and Technological Research, Polish Academy of Sciences, Pawinskiego 5B, 02-106 Warsaw, Poland
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18
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Roosen-Runge F, Schurtenberger P, Stradner A. Self-diffusion of nonspherical particles fundamentally conflicts with effective sphere models. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:154002. [PMID: 33498038 DOI: 10.1088/1361-648x/abdff9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 01/26/2021] [Indexed: 06/12/2023]
Abstract
Modeling diffusion of nonspherical particles presents an unsolved and considerable challenge, despite its importance for the understanding of crowding effects in biology, food technology and formulation science. A common approach in experiment and simulation is to map nonspherical objects on effective spheres to subsequently use the established predictions for spheres to approximate phenomena for nonspherical particles. Using numerical evaluation of the hydrodynamic mobility tensor, we show that this so-called effective sphere model fundamentally fails to represent the self-diffusion in solutions of ellipsoids as well as rod-like assemblies of spherical beads. The effective sphere model drastically overestimates the slowing down of self-diffusion down to volume fractions below 0.01. Furthermore, even the linear term relevant at lower volume fraction is inaccurate, linked to a fundamental misconception of effective sphere models. To overcome the severe problems related with the use of effective sphere models, we suggest a protocol to predict the short-time self-diffusion of rod-like systems, based on simulations with hydrodynamic interactions that become feasible even for more complex molecules as the essential observable shows a negligible system-size effect.
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Affiliation(s)
- Felix Roosen-Runge
- Division of Physical Chemistry, Lund University, Naturvetarvägen 14, 22100 Lund, Sweden
- Department of Biomedical Sciences and Biofilms-Research Center for Biointerfaces (BRCB), Faculty of Health and Society, Malmö University, Sweden
| | - Peter Schurtenberger
- Division of Physical Chemistry, Lund University, Naturvetarvägen 14, 22100 Lund, Sweden
| | - Anna Stradner
- Division of Physical Chemistry, Lund University, Naturvetarvägen 14, 22100 Lund, Sweden
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19
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Das M, Chambon L, Varga Z, Vamvakaki M, Swan JW, Petekidis G. Shear driven vorticity aligned flocs in a suspension of attractive rigid rods. SOFT MATTER 2021; 17:1232-1245. [PMID: 33300930 DOI: 10.1039/d0sm01576h] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A combination of rheology, optical microscopy and computer simulations was used to investigate the microstructural changes of a semi-dilute suspension of attractive rigid rods in an imposed shear flow. The aim is to understand the relation of the microstructure with the viscoelastic response, and the yielding and flow behaviour in different shear regimes of gels built from rodlike colloids. A semi-dilute suspension of micron sized, rodlike silica particles suspended in 11 M CsCl salt solution was used as a model system for attractive rods' gel. Upon application of steady shear the gel microstructure rearranges in different states and exhibits flow instabilities depending on shear rate, attraction strength, volume fraction and geometrical confinement. At low rod volume fractions, the suspension forms large, vorticity aligned, particle rich flocs that roll in the flow-vorticity plane, an effect that is due to an interplay between hydrodynamic interactions and geometrical confinement as suggested by computer simulations. Experimental data allow the creation of a state diagram, as a function of volume fraction and shear rates, identifying regimes of stable (or unstable) floc formation and of homogeneous gel or broken clusters. The transition is related to dimensionless Mason number, defined as the ratio of shear forces to interparticle attractive force.
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Affiliation(s)
- Mohan Das
- IESL - FORTH and Department of Material Science and Technology, University of Crete, GR - 71110, Heraklion, Greece.
| | - Lucille Chambon
- IESL - FORTH and Department of Material Science and Technology, University of Crete, GR - 71110, Heraklion, Greece.
| | - Zsigmond Varga
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Maria Vamvakaki
- IESL - FORTH and Department of Material Science and Technology, University of Crete, GR - 71110, Heraklion, Greece.
| | - James W Swan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - George Petekidis
- IESL - FORTH and Department of Material Science and Technology, University of Crete, GR - 71110, Heraklion, Greece.
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20
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Sprinkle B, van der Wee EB, Luo Y, Driscoll MM, Donev A. Driven dynamics in dense suspensions of microrollers. SOFT MATTER 2020; 16:7982-8001. [PMID: 32776032 DOI: 10.1039/d0sm00879f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We perform detailed computational and experimental measurements of the driven dynamics of a dense, uniform suspension of sedimented microrollers driven by a magnetic field rotating around an axis parallel to the floor. We develop a lubrication-corrected Brownian dynamics method for dense suspensions of driven colloids sedimented above a bottom wall. The numerical method adds lubrication friction between nearby pairs of particles, as well as particles and the bottom wall, to a minimally-resolved model of the far-field hydrodynamic interactions. Our experiments combine fluorescent labeling with particle tracking to trace the trajectories of individual particles in a dense suspension, and to measure their propulsion velocities. Previous computational studies [B. Sprinkle et al., J. Chem. Phys., 2017, 147, 244103] predicted that at sufficiently high densities a uniform suspension of microrollers separates into two layers, a slow monolayer right above the wall, and a fast layer on top of the bottom layer. Here we verify this prediction, showing good quantitative agreement between the bimodal distribution of particle velocities predicted by the lubrication-corrected Brownian dynamics and those measured in the experiments. The computational method accurately predicts the rate at which particles are observed to switch between the slow and fast layers in the experiments. We also use our numerical method to demonstrate the important role that pairwise lubrication plays in motility-induced phase separation in dense monolayers of colloidal microrollers, as recently suggested for suspensions of Quincke rollers [D. Geyer et al., Phys. Rev. X, 2019, 9(3), 031043].
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Affiliation(s)
- Brennan Sprinkle
- Courant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA
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21
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Sherman ZM, Swan JW. Spontaneous Electrokinetic Magnus Effect. PHYSICAL REVIEW LETTERS 2020; 124:208002. [PMID: 32501074 DOI: 10.1103/physrevlett.124.208002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 04/13/2020] [Indexed: 06/11/2023]
Abstract
Colloids dispersed in electrolytes and exposed to an electric field produce a locally polarized cloud of ions around them. Above a critical electric field strength, an instability occurs causing these ion clouds to break symmetry leading to spontaneous rotation of particles about an axis orthogonal to the applied field, a phenomenon named Quincke rotation. In this Letter, we characterize a new mode of electrokinetic transport. If the colloids have a net charge, Quincke rotation couples with electrophoretic motion and propels particles in a direction orthogonal to both the applied field and the axis of rotation. This motion is a spontaneous, electrokinetic analogue to the well-known Magnus effect. Typically, motion orthogonal to a field requires anisotropy in particle shape, dielectric properties, or boundary geometry. Here, the electrokinetic Magnus (EKM) effect occurs for spheres with isotropic properties in an unbounded environment, with the Quincke rotation instability providing the broken symmetry needed to drive orthogonal motion. We study the EKM effect using explicit ion, Brownian dynamics simulations and develop a simple, continuum, analytic electrokinetic theory, which are in agreement. We also explain how nonlinearities in the theoretical description of the ions affect Quincke rotation and the EKM effect.
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Affiliation(s)
- Zachary M Sherman
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - James W Swan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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22
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Silmore KS, Swan JW. Collective mode Brownian dynamics: A method for fast relaxation of statistical ensembles. J Chem Phys 2020; 152:094104. [DOI: 10.1063/1.5129648] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Kevin S. Silmore
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - James W. Swan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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23
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Young CD, Sing CE. Simulation of semidilute polymer solutions in planar extensional flow via conformationally averaged Brownian noise. J Chem Phys 2019; 151:124907. [PMID: 31575212 DOI: 10.1063/1.5122811] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The dynamics and rheology of semidilute polymer solutions in strong flows are of great practical relevance. Processing applications can in principle be designed utilizing the relationship between nonequilibrium polymer conformations and the material properties of the solution. However, the interplay between concentration, flow, hydrodynamic interactions (HIs), and topological interactions which govern semidilute polymer dynamics is challenging to characterize. Brownian dynamics (BD) simulations are particularly valuable as a way to directly visualize how molecular interactions arise in these systems and are quantitatively comparable to single-molecule experiments. However, such simulations are often computationally intractable and are limited by the need to calculate the correlated Brownian noise via decomposition of the diffusion tensor. Previously, we have introduced an iterative conformational averaging (CA) method for BD simulations which bypasses these limitations by preaveraging the HI and Brownian noise in an iterative procedure. In this work, we generalize the CA method to flowing semidilute solutions by introducing a conformation dependent diffusion tensor and a strain dependent approximation to the conformationally averaged Brownian noise. We find that this approach nearly quantitatively reproduces both transient and steady state polymer dynamics and rheology while achieving an order of magnitude computational acceleration. We then utilize the CA method to investigate the concentration and flow rate dependence of polymer dynamics in planar extensional flows. Our results are consistent with previous experimental and simulation studies and provide a detailed view of broad conformational distributions in the semidilute regime. We observe interconversion between stretched and coiled states at steady state, which we conjecture occur due to the effect of concentration on the conformation dependent polymer drag. Additionally, we observe transient flow-induced intermolecular hooks in the startup of flow which lead to diverse and unique stretching pathways.
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Affiliation(s)
- Charles D Young
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Charles E Sing
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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24
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Sherman ZM, Pallone JL, Erb RM, Swan JW. Enhanced diffusion and magnetophoresis of paramagnetic colloidal particles in rotating magnetic fields. SOFT MATTER 2019; 15:6677-6689. [PMID: 31397836 DOI: 10.1039/c9sm00890j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Dispersions of paramagnetic colloids can be manipulated with external magnetic fields to assemble structures via dipolar assembly and control transport via magnetophoresis. For fields held steady in time, the dispersion structure and dynamic properties are coupled. This coupling can be problematic when designing processes involving field-induced forces, as particle aggregation competes against and hinders particle transport. Time-varying fields drive dispersions out-of-equilibrium, allowing the structure and dynamics to be tuned independently. Rotating the magnetic field direction using two biaxial fields is a particularly effective mode of time-variation and has been used experimentally to enhance particle transport. Fundamental transport properties, like the diffusivity and magnetophoretic mobility, dictate dispersions' out-of-equilibrium responses to such time-varying fields, and are therefore crucial to understand to effectively design processes utilizing rotating fields. However, a systematic study of these dynamic quantities in rotating fields has not been performed. Here, we investigate the transport properties of dispersions of paramagnetic colloids in rotating magnetic fields using dynamic simulations. We find that self-diffusion of particles is enhanced in rotating fields compared to steady fields, and that the self-diffusivity in the plane of rotation reaches a maximum value at intermediate rotation frequencies that is larger than the Stokes-Einstein diffusivity of an isolated particle. We also show that, while the magnetophoretic velocity of particles through the bulk in a field gradient decreases with increasing rotation frequency, the enhanced in-plane diffusion allows for faster magnetophoretic transport through porous materials in rotating fields. We examine the effect of porous confinement on the transport properties in rotating fields and find enhanced diffusion at all pore sizes. The confined and bulk values of the transport properties are leveraged in simple models of magnetophoresis through tortuous porous media.
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Affiliation(s)
- Zachary M Sherman
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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25
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Wang G, Swan JW. Surface heterogeneity affects percolation and gelation of colloids: dynamic simulations with random patchy spheres. SOFT MATTER 2019; 15:5094-5108. [PMID: 31184670 DOI: 10.1039/c9sm00607a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Surface heterogeneity of colloidal particles has a significant impact on their structure in solution and their rheological properties. During particle synthesis, heterogeneous chemical functionalization, processes of self-assembly, or phase separation, can all lead to heterogeneous colloidal surfaces which impart anisotropic interactions to suspended particles. Additionally, an important class of colloids, biological macromolecules, exhibit similar localized, short-ranged, anisotropic interactions, which have a significant impact on their solution properties. Therefore, understanding the assembly and rheology of such colloids can provide insight into a wide variety of relevant physical systems. In this computational study, we investigate dispersions of particles having surface patches with randomized functionality as a model for heterogeneous colloids. We use Brownian dynamics simulations with hydrodynamic interactions to explore the differences between these random patchy particles and homogeneous (or isotropic) particles. The common basis used for comparing dispersions of particles with different surface functionality is equality of the second virial coefficient, so that dispersions of particles with different patterns of surface heterogeneity are similar thermodynamically at low particle concentrations. We show that at modest particle concentrations, significant deviations from the isotropic model are evident in the dispersion micro-structure, giving drastically different percolation transition points depending on the degree of surface heterogeneity. However, these deviations can be rationalized and a universal percolation criteria derived in terms of the osmotic pressure of the dispersion. Heterogeneous interactions also impose extra constraints on the relative translation and rotation between neighboring particles, which increase the viscosity and elastic modulus of aggregated dispersions and gels built from heterogeneous colloids and shifts the gel point measurably.
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Affiliation(s)
- Gang Wang
- Massachusetts Institute of Technology, Department of Chemical Engineering, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
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26
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Varga Z, Grenard V, Pecorario S, Taberlet N, Dolique V, Manneville S, Divoux T, McKinley GH, Swan JW. Hydrodynamics control shear-induced pattern formation in attractive suspensions. Proc Natl Acad Sci U S A 2019; 116:12193-12198. [PMID: 31164423 PMCID: PMC6591707 DOI: 10.1073/pnas.1901370116] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Dilute suspensions of repulsive particles exhibit a Newtonian response to flow that can be accurately predicted by the particle volume fraction and the viscosity of the suspending fluid. However, such a description fails when the particles are weakly attractive. In a simple shear flow, suspensions of attractive particles exhibit complex, anisotropic microstructures and flow instabilities that are poorly understood and plague industrial processes. One such phenomenon, the formation of log-rolling flocs, which is ubiquitously observed in suspensions of attractive particles that are sheared while confined between parallel plates, is an exemplar of this phenomenology. Combining experiments and discrete element simulations, we demonstrate that this shear-induced structuring is driven by hydrodynamic coupling between the flocs and the confining boundaries. Clusters of particles trigger the formation of viscous eddies that are spaced periodically and whose centers act as stable regions where particles aggregate to form flocs spanning the vorticity direction. Simulation results for the wavelength of the periodic pattern of stripes formed by the logs and for the log diameter are in quantitative agreement with experimental observations on both colloidal and noncolloidal suspensions. Numerical and experimental results are successfully combined by means of rescaling in terms of a Mason number that describes the strength of the shear flow relative to the rupture force between contacting particles in the flocs. The introduction of this dimensionless group leads to a universal stability diagram for the log-rolling structures and allows for application of shear-induced structuring as a tool for assembling and patterning suspensions of attractive particles.
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Affiliation(s)
- Zsigmond Varga
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Vincent Grenard
- Laboratoire de Physique, École Normale Supérieure de Lyon, Université Claude Bernard, Université de Lyon, CNRS, F-69342 Lyon, France
| | - Stefano Pecorario
- Laboratoire de Physique, École Normale Supérieure de Lyon, Université Claude Bernard, Université de Lyon, CNRS, F-69342 Lyon, France
| | - Nicolas Taberlet
- Laboratoire de Physique, École Normale Supérieure de Lyon, Université Claude Bernard, Université de Lyon, CNRS, F-69342 Lyon, France
| | - Vincent Dolique
- Laboratoire de Physique, École Normale Supérieure de Lyon, Université Claude Bernard, Université de Lyon, CNRS, F-69342 Lyon, France
| | - Sébastien Manneville
- Laboratoire de Physique, École Normale Supérieure de Lyon, Université Claude Bernard, Université de Lyon, CNRS, F-69342 Lyon, France
| | - Thibaut Divoux
- Centre de Recherche Paul Pascal, CNRS UMR 5031, 33600 Pessac, France
- MultiScale Material Science for Energy and Environment, Unité Mixte Internationale 3466, CNRS-Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Gareth H McKinley
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - James W Swan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139;
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27
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Whitaker KA, Varga Z, Hsiao LC, Solomon MJ, Swan JW, Furst EM. Colloidal gel elasticity arises from the packing of locally glassy clusters. Nat Commun 2019; 10:2237. [PMID: 31110184 PMCID: PMC6527676 DOI: 10.1038/s41467-019-10039-w] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 04/10/2019] [Indexed: 12/03/2022] Open
Abstract
Colloidal gels formed by arrested phase separation are found widely in agriculture, biotechnology, and advanced manufacturing; yet, the emergence of elasticity and the nature of the arrested state in these abundant materials remains unresolved. Here, the quantitative agreement between integrated experimental, computational, and graph theoretic approaches are used to understand the arrested state and the origins of the gel elastic response. The micro-structural source of elasticity is identified by the l-balanced graph partition of the gels into minimally interconnected clusters that act as rigid, load bearing units. The number density of cluster-cluster connections grows with increasing attraction, and explains the emergence of elasticity in the network through the classic Cauchy-Born theory. Clusters are amorphous and iso-static. The internal cluster concentration maps onto the known attractive glass line of sticky colloids at low attraction strengths and extends it to higher strengths and lower particle volume fractions.
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Affiliation(s)
- Kathryn A Whitaker
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, 19716, USA
- Dow, 1702 Building, Midland, MI, 48667, USA
| | - Zsigmond Varga
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Lilian C Hsiao
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Engineering Building I, Raleigh, NC, 27695, USA
| | - Michael J Solomon
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
| | - James W Swan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
| | - Eric M Furst
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, 19716, USA.
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28
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Sherman ZM, Swan JW. Transmutable Colloidal Crystals and Active Phase Separation via Dynamic, Directed Self-Assembly with Toggled External Fields. ACS NANO 2019; 13:764-771. [PMID: 30605597 DOI: 10.1021/acsnano.8b08076] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A diverse set of functional materials can be fabricated by assembling dispersions of colloids and nanoparticles. Two principal engineering challenges prevent efficient production of these materials: first, scalable synthesis of particles with carefully tailored interactions required to generate complex structures, and second, the propensity of such materials to arrest in undesirable metastable states. Active assembly processes, such as dynamic, directed self-assembly in which the interactions among particles are externally controlled and vary over time, offer a promising method to address these challenges. For dispersions of polarizable dielectric or paramagnetic nanoparticles, an effective mode of active assembly can be achieved by toggling an external electric or magnetic field, which induces attractive particle interactions, on and off cyclically over time. Here, we develop computational and theoretical models for such active assembly processes and find that cyclically toggling the external field leads to growth of colloidal crystals at significantly faster rates and with many fewer defects than for assembly in a steady field. The active process stabilizes phases that are only metastable in steady fields, including a dense fluid phase and body-centered orthorhombic crystals. The growth mechanism and terminal structure of the dispersion are easily controlled by the toggling protocol, and the toggle parameters can be used to continuously transmute between crystal structures with different lattice parameters. Finally, we show how results from linear irreversible thermodynamics can be used to predict the dissipative terminal states of the active assembly process in terms of parameters of the toggling protocol.
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Affiliation(s)
- Zachary M Sherman
- Department of Chemical Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - James W Swan
- Department of Chemical Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
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29
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Young CD, Marvin M, Sing CE. Conformationally averaged iterative Brownian dynamics simulations of semidilute polymer solutions. J Chem Phys 2018; 149:174904. [DOI: 10.1063/1.5041453] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Charles D. Young
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | | | - Charles E. Sing
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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30
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Sherman ZM, Ghosh D, Swan JW. Field-Directed Self-Assembly of Mutually Polarizable Nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:7117-7134. [PMID: 29782173 DOI: 10.1021/acs.langmuir.8b01135] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Directed assembly of dielectric and paramagnetic nanoparticles can be used to synthesize diverse functional materials that polarize in response to an externally applied electric or magnetic field. However, theories capable of predicting the self-assembled states are lacking. In the proposed work, we develop a complete thermodynamic description of such assemblies for spherical nanoparticles. We show how an important physical feature of these types of particles, mutual polarization, sculpts the free energy landscape and has a remarkably strong influence on the nature of the self-assembled states. Modeling the mutual polarization among nanoparticles requires solving a many-bodied problem for the particle dipole moments. Typically, this computationally expensive task is avoided by neglecting mutual polarization and assuming that each particle in a concentrated dispersion acquires the same dipole moment as a single, isolated particle. Although valid in the limit of small dielectric or permeability contrasts between particles and solvent, this constant dipole assumption leads to qualitatively incorrect predictions for coexisting phases in equilibrium at large dielectric or permeability contrasts. Correctly accounting for mutual polarization enables a thermodynamic theory that describes the equilibrium phase diagram of polarizable dispersions in terms of experimentally controllable variables. Our theoretical predictions agree with the phase behavior we observe in dynamic simulations of these dispersions as well as that in experiments of field-directed structural transitions. In contrast to predictions of a constant dipole model, we find that dispersions of particles with different dielectric constants or magnetic permeabilities exhibit qualitatively different phase behavior. This new model also predicts the existence of a eutectic point at which two crystalline phases and a disordered phase of nanoparticles all simultaneously coexist.
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Affiliation(s)
- Zachary M Sherman
- Department of Chemical Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - Dipanjan Ghosh
- Department of Chemical Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - James W Swan
- Department of Chemical Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
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31
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Abstract
We develop a Split Reactive Brownian Dynamics (SRBD) algorithm for particle simulations of reaction-diffusion systems based on the Doi or volume reactivity model, in which pairs of particles react with a specified Poisson rate if they are closer than a chosen reactive distance. In our Doi model, we ensure that the microscopic reaction rules for various association and dissociation reactions are consistent with detailed balance (time reversibility) at thermodynamic equilibrium. The SRBD algorithm uses Strang splitting in time to separate reaction and diffusion and solves both the diffusion-only and reaction-only subproblems exactly, even at high packing densities. To efficiently process reactions without uncontrolled approximations, SRBD employs an event-driven algorithm that processes reactions in a time-ordered sequence over the duration of the time step. A grid of cells with size larger than all of the reactive distances is used to schedule and process the reactions, but unlike traditional grid-based methods such as reaction-diffusion master equation algorithms, the results of SRBD are statistically independent of the size of the grid used to accelerate the processing of reactions. We use the SRBD algorithm to compute the effective macroscopic reaction rate for both reaction-limited and diffusion-limited irreversible association in three dimensions and compare to existing theoretical predictions at low and moderate densities. We also study long-time tails in the time correlation functions for reversible association at thermodynamic equilibrium and compare to recent theoretical predictions. Finally, we compare different particle and continuum methods on a model exhibiting a Turing-like instability and pattern formation. Our studies reinforce the common finding that microscopic mechanisms and correlations matter for diffusion-limited systems, making continuum and even mesoscopic modeling of such systems difficult or impossible. We also find that for models in which particles diffuse off lattice, such as the Doi model, reactions lead to a spurious enhancement of the effective diffusion coefficients.
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Affiliation(s)
- Aleksandar Donev
- Courant Institute of Mathematical Sciences, New York University, New York, New York 10012, USA
| | - Chiao-Yu Yang
- Courant Institute of Mathematical Sciences, New York University, New York, New York 10012, USA
| | - Changho Kim
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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32
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Balboa Usabiaga F, Delmotte B, Donev A. Brownian dynamics of confined suspensions of active microrollers. J Chem Phys 2018; 146:134104. [PMID: 28390356 DOI: 10.1063/1.4979494] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We develop efficient numerical methods for performing many-body Brownian dynamics simulations of a recently observed fingering instability in an active suspension of colloidal rollers sedimented above a wall [M. Driscoll, B. Delmotte, M. Youssef, S. Sacanna, A. Donev, and P. Chaikin, Nat. Phys. (2016), preprint arXiv:1609.08673. We present a stochastic Adams-Bashforth integrator for the equations of Brownian dynamics, which has the same cost but is more accurate than the widely used Euler-Maruyama scheme, and use a random finite difference to capture the stochastic drift proportional to the divergence of the configuration-dependent mobility matrix. We generate the Brownian increments using a Krylov method and show that for particles confined to remain in the vicinity of a no-slip wall by gravity or active flows, the number of iterations is independent of the number of particles. Our numerical experiments with active rollers show that the thermal fluctuations set the characteristic height of the colloids above the wall, both in the initial condition and the subsequent evolution dominated by active flows. The characteristic height in turn controls the time scale and wavelength for the development of the fingering instability.
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Affiliation(s)
| | - Blaise Delmotte
- Courant Institute of Mathematical Sciences, New York University, New York, New York 10012, USA
| | - Aleksandar Donev
- Courant Institute of Mathematical Sciences, New York University, New York, New York 10012, USA
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33
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Daddi-Moussa-Ider A, Lisicki M, Hoell C, Löwen H. Swimming trajectories of a three-sphere microswimmer near a wall. J Chem Phys 2018; 148:134904. [DOI: 10.1063/1.5021027] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Abdallah Daddi-Moussa-Ider
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Maciej Lisicki
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Rd., Cambridge CB3 0WA, United Kingdom
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
| | - Christian Hoell
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Hartmut Löwen
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
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34
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You D, Min X, Liu L, Ren Z, Xiao X, Pavlostathis SG, Luo J, Luo X. New insight on the adsorption capacity of metallogels for antimonite and antimonate removal: From experimental to theoretical study. JOURNAL OF HAZARDOUS MATERIALS 2018; 346:218-225. [PMID: 29277041 DOI: 10.1016/j.jhazmat.2017.12.035] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Revised: 11/23/2017] [Accepted: 12/12/2017] [Indexed: 06/07/2023]
Abstract
Development of high capacity material for antimonite (Sb(III)) and antimonate (Sb(V)) removal is the key to solving water antimony contamination. Three-dimensional Cu(II)-specific metallogels (Cu-MG), which are considered to have high density adsorption sites for antimony (Sb), were first applied to adsorb Sb(III) and Sb(V). Batch assays resulted in adsorption capacities of Cu-MG for Sb(III) and Sb(V) at 102.4 mg/g and 264.1 mg/g, respectively. In addition, the adsorption capacity for Sb(III) was up to 225.7 mg/g using in situ oxidation. Kinetic assays resulted in more than 90% removal of Sb in 30 min. X-ray photoelectron spectroscopy (XPS) revealed the adsorption of Sb depended mainly on coordination interactions of vacant orbitals of the Cu atom with the lone-pairs of the O atom of Sb(OH)3 or Sb(OH)6-. Adsorption energy based on density functional theory (DFT) confirmed that Sb(III) adsorbed as a single layer whereas Sb(V) adsorbed as a multi-layer. These findings are consistent with experimental results. In addition, DFT calculations revealed that the Cu-MG theoretical capacity for Sb(V) adsorption is higher than for Sb(III). Cu-MG is a new and promising class of adsorbents for the removal of Sb(III) and Sb(V) from contaminated water.
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Affiliation(s)
- Deng You
- Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, PR China
| | - Xiaoye Min
- Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, PR China
| | - Lingling Liu
- Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, PR China
| | - Zhong Ren
- Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, PR China
| | - Xiao Xiao
- Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, PR China
| | - Spyros G Pavlostathis
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States
| | - Jinming Luo
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States; Brook Byers Institute for Sustainable Systems, Georgia Institute of Technology, Atlanta, GA 30332, United States
| | - Xubiao Luo
- Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, PR China.
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35
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Wang G, Varga Z, Hofmann J, Zarraga IE, Swan JW. Structure and Relaxation in Solutions of Monoclonal Antibodies. J Phys Chem B 2018; 122:2867-2880. [PMID: 29469576 DOI: 10.1021/acs.jpcb.7b11053] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Reversible self-association of therapeutic antibodies is a key factor in high protein solution viscosities. In the present work, a coarse-grained computational model accounting for electrostatic, dispersion, and long-ranged hydrodynamic interactions of two model monoclonal antibodies is applied to understand the nature of self-association, predicting the solution microstructure and resulting transport properties of the solution. For the proteins investigated, the structure factor across a range of solution conditions shows quantitative agreement with neutron-scattering experiments. We observe a homogeneous, dynamical association of the antibodies with no evidence of phase separation. Calculations of self-diffusivity and viscosity from coarse-grained dynamic simulations show the appropriate trends with concentration but, respectively, over- and under-predict the experimentally measured values. By adding constraints to the self-associated clusters that rigidify them under flow, prediction of the transport properties is significantly improved with respect to experimental measurements. We hypothesize that these rigidity constraints are associated with missing degrees of freedom in the coarse-grained model resulting from patchy and heterogeneous interactions among coarse-grained domains. These results demonstrate how structural anisotropy and anisotropy of interactions generated by features at the 2-5 nm length scale in antibodies are sufficient to recover the dynamics and rheological properties of these important macromolecular solutions.
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Affiliation(s)
- Gang Wang
- Department of Chemical Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - Zsigmond Varga
- Department of Chemical Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - Jennifer Hofmann
- Department of Chemical Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - Isidro E Zarraga
- Late Stage Pharmaceutical Development , Genentech Inc. , South San Francisco , California 94080 , United States
| | - James W Swan
- Department of Chemical Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
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36
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Abstract
The normal modes and relaxation rates of weak colloidal gels are investigated in calculations using different models of the hydrodynamic interactions between suspended particles. The relaxation spectrum is computed for freely draining, Rotne-Prager-Yamakawa, and accelerated Stokesian dynamics approximations of the hydrodynamic mobility in a normal mode analysis of a harmonic network representing several colloidal gels. We find that the density of states and spatial structure of the normal modes are fundamentally altered by long-ranged hydrodynamic coupling among the particles. Short-ranged coupling due to hydrodynamic lubrication affects only the relaxation rates of short-wavelength modes. Hydrodynamic models accounting for long-ranged coupling exhibit a microscopic relaxation rate for each normal mode, λ that scales as l^{-2}, where l is the spatial correlation length of the normal mode. For the freely draining approximation, which neglects long-ranged coupling, the microscopic relaxation rate scales as l^{-γ}, where γ varies between three and two with increasing particle volume fraction. A simple phenomenological model of the internal elastic response to normal mode fluctuations is developed, which shows that long-ranged hydrodynamic interactions play a central role in the viscoelasticity of the gel network. Dynamic simulations of hard spheres that gel in response to short-ranged depletion attractions are used to test the applicability of the density of states predictions. For particle concentrations up to 30% by volume, the power law decay of the relaxation modulus in simulations accounting for long-ranged hydrodynamic interactions agrees with predictions generated by the density of states of the corresponding harmonic networks as well as experimental measurements. For higher volume fractions, excluded volume interactions dominate the stress response, and the prediction from the harmonic network density of states fails. Analogous to the Zimm model in polymer physics, our results indicate that long-ranged hydrodynamic interactions play a crucial role in determining the microscopic dynamics and macroscopic properties of weak colloidal gels.
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Affiliation(s)
- Zsigmond Varga
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - James W Swan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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37
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Spyrogianni A, Karadima KS, Goudeli E, Mavrantzas VG, Pratsinis SE. Mobility and settling rate of agglomerates of polydisperse nanoparticles. J Chem Phys 2018; 148:064703. [PMID: 29448768 DOI: 10.1063/1.5012037] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Agglomerate settling impacts nanotoxicology and nanomedicine as well as the stability of engineered nanofluids. Here, the mobility of nanostructured fractal-like SiO2 agglomerates in water is investigated and their settling rate in infinitely dilute suspensions is calculated by a Brownian dynamics algorithm tracking the agglomerate translational and rotational motion. The corresponding friction matrices are obtained using the HYDRO++ algorithm [J. G. de la Torre, G. del Rio Echenique, and A. Ortega, J. Phys. Chem. B 111, 955 (2007)] from the Kirkwood-Riseman theory accounting for hydrodynamic interactions of primary particles (PPs) through the Rotne-Prager-Yamakawa tensor, properly modified for polydisperse PPs. Agglomerates are generated by an event-driven method and have constant mass fractal dimension but varying PP size distribution, mass, and relative shape anisotropy. The calculated diffusion coefficient from HYDRO++ is used to obtain the agglomerate mobility diameter dm and is compared with that from scaling laws for fractal-like agglomerates. The ratio dm/dg of the mobility diameter to the gyration diameter of the agglomerate decreases with increasing relative shape anisotropy. For constant dm and mean dp, the agglomerate settling rate, us, increases with increasing PP geometric standard deviation σp,g (polydispersity). A linear relationship between us and agglomerate mass to dm ratio, m/dm, is revealed and attributed to the fast Brownian rotation of such small and light nanoparticle agglomerates. An analytical expression for the us of agglomerates consisting of polydisperse PPs is then derived, us=1-ρfρpg3πμmdm (ρf is the density of the fluid, ρp is the density of PPs, μ is the viscosity of the fluid, and g is the acceleration of gravity), valid for agglomerates for which the characteristic rotational time is considerably shorter than their settling time. Our calculations demonstrate that the commonly made assumption of monodisperse PPs underestimates us by a fraction depending on σp,g and agglomerate mass mobility exponent. Simulations are in excellent agreement with deposition rate measurements of fumed SiO2 agglomerates in water.
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Affiliation(s)
- Anastasia Spyrogianni
- Department of Mechanical and Process Engineering, ETH Zurich, Zurich 8092, Switzerland
| | - Katerina S Karadima
- Department of Chemical Engineering, University of Patras, Patras 26504, Greece
| | - Eirini Goudeli
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Vlasis G Mavrantzas
- Department of Mechanical and Process Engineering, ETH Zurich, Zurich 8092, Switzerland
| | - Sotiris E Pratsinis
- Department of Mechanical and Process Engineering, ETH Zurich, Zurich 8092, Switzerland
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38
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Fiore AM, Swan JW. Rapid sampling of stochastic displacements in Brownian dynamics simulations with stresslet constraints. J Chem Phys 2018; 148:044114. [DOI: 10.1063/1.5005887] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Andrew M. Fiore
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - James W. Swan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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39
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Sprinkle B, Balboa Usabiaga F, Patankar NA, Donev A. Large scale Brownian dynamics of confined suspensions of rigid particles. J Chem Phys 2017; 147:244103. [DOI: 10.1063/1.5003833] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Brennan Sprinkle
- McCormick School of Engineering, Northwestern University, Evanston, Illinois 60208, USA
| | - Florencio Balboa Usabiaga
- Courant Institute of Mathematical Sciences, New York University, New York, New York 10012, USA
- Center for Computational Biology, Flatiron Institute, Simons Foundation, New York, New York 10010, USA
| | - Neelesh A. Patankar
- McCormick School of Engineering, Northwestern University, Evanston, Illinois 60208, USA
| | - Aleksandar Donev
- Courant Institute of Mathematical Sciences, New York University, New York, New York 10012, USA
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