2024

2023

From ultra-fast growth to avalanche growth in devitrifying glasses

Taiki Yanagishima, John Russo, Roel P A Dullens, and Hajime Tanaka

J. Chem. Phys. 2023 159 064510

During devitrification, pre-existing crystallites grow by adding particles to their surface via a process that is either thermally activated (diffusive mode) or happens without kinetic barriers (fast ...

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Effect of curvature on the diffusion of colloidal bananas

Justin-Aurel Ulbrich, Carla Fernández-Rico, Brian Rost, Jacopo Vialetto, Lucio Isa, Jeffrey S Urbach, and Roel P A Dullens

Phys. Rev. E 2023 107 042602

Anisotropic colloidal particles exhibit complex dynamics which play a crucial role in their functionality, transport, and phase behavior. In this Letter, we investigate the two-dimensional diffusion o ...

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2022

2021

Grain boundary characterization from particle coordinates

Nicholas HP Orr, Taiki Yanagishima, Eric Maire, and Roel PA Dullens

Phys. Rev. Materials 2021 5 123605

We present a method to locate and characterize grain boundaries in polycrystalline materials from the real-space coordinates of their constituent particles. The method is robust against imperfections ...

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Towards Glasses with Permanent Stability

Taiki Yanagishima, John Russo, Roel PA Dullens, and Hajime Tanaka

Phys. Rev. Mater. 2021 127 215501

We present a method to locate and characterize grain boundaries in polycrystalline materials from the real-space coordinates of their constituent particles. The method is robust against imperfections ...

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2020

Generalized network theory of physical two-dimensional systems

David O Morley, Alice L Thorneywork, Roel PA Dullens, and Mark Wilson

Phys. Rev. E 2020 101 042309

The properties of a wide range of two-dimensional network materials are investigated by developing a generalized network theory. The methods developed are shown to be applicable to a wide range of sys ...

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2019

Synthesis of Colloidal SU-8 Polymer Rods Using Sonication

Carla Fernandez-Rico, Taiki Yanagishima, Arran Curran, Dirk GAL Aarts, and Roel PA Dullens

Adv. Mater. 2019 31 1807514

The bulk synthesis of fluorescent colloidal SU-8 polymer rods with tunable dimensions is described. The colloidal SU-8 rods are prepared by shearing an emulsion of SU-8 polymer droplets and then expos ...

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Colloidal rods in optical potential energy landscapes

Joshua L Abbott, James A Spiers, Yongxiang Gao, Dirk GAL Aarts, and Roel PA Dullens

J. Phys. D: Appl. Phys 2019 52 024002

We study the static and dynamic behaviour of colloidal rods in an optical potential energy landscape. We explore the stable states of a colloidal rod in a single optical trap close to a flat wall. Her ...

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2018

Capillary nematisation of colloidal rods in confinement

Kira E Klop, Roel PA Dullens, Paul M Lettinga, Sergei A Sergei, and Dirk GAL Aarts

Mol. Phys. 2018 116 2864

We confine a colloidal liquid crystal between parallel plates separated down to several times the rod length. By connecting the system to a reservoir we effectively create a grand canonical system, in ...

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Bulk synthesis of silver-head colloidal rodlike micromotors

Yongxiang Gao, Roel PA Dullens, and Dirk GAL Aarts

Soft Matter 2018 14 7119

Colloidal particles with asymmetric catalytic activities are emerging micro/nanomotors that harvest chemical energy for propulsion in fluids. It is of general interest to produce such particles with h ...

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Structure factors in a two-dimensional binary colloidal hard sphere system

Alice L Thorneywork, Simon K Schnyder, Dirk GAL Aarts, Juergen Horbach, Roland Roth, and Roel PA Dullens

Mol. Phys. 2018 116 3245

Hard disks are one of the simplest interacting many-body model system in two dimensions (2D). Here, we present a comprehensive set of measurements of the static structure factors for quasi-2D monodisp ...

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Directed self-assembly into low-density colloidal liquid crystal phases

Yongxiang Gao, Flavio Romano, Roel PA Dullens, Jonathan K Doye, and Dirk GAL Aarts

Phys. Rev. Materials 2018 2 015601

Alignment of anisometric particles into liquid crystals (LCs) often results from an entropic competition between their rotational and translational degrees of freedom at dense packings. Here we show t ...

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2017

Two-Dimensional Melting of Colloidal Hard Spheres

Alice L Thorneywork, Joshua L Abbott, Dirk G A L Aarts, and Roel P A Dullens

Phys. Rev. Lett. 2017 118 158001

We study the melting of quasi-two-dimensional colloidal hard spheres by considering a tilted monolayer of particles in sedimentation-diffusion equilibrium. In particular, we measure the equation of st ...

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Dynamic heterogeneities and non-Gaussian behavior in two-dimensional randomly confined colloidal fluids

Simon K Schnyder, Thomas O E Skinner, Alice L Thorneywork, Dirk G A L Aarts, Juergen Horbach, and Roel P A Dullens

Phys. Rev. E 2017 95 032602

A binary mixture of superparamagnetic colloidal particles is confined between glass plates such that the large particles become fixed and provide a two-dimensional disorderedmatrix for the still mobile small particles, which form a fluid. By varying fluid and matrix area fractions and tuning the i ...

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Colloidal liquid crystals in square confinement: isotropic, nematic and smectic phases

Louis B G Cortes, Yongxiang Gao, Roel P A Dullens, and Dirk G A L Aarts

J. PHYS.-CONDENS. MAT. 2017 29 064003

We report on the confinement of colloidal liquid crystals in three dimensional chambers with a square footprint. To this end we use colloidal silica rods and exploit their relatively large density difference with respect to the dispersing solvent to study isotropic, nematic and smectic phases confin ...

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Self-diffusion in two-dimensional binary colloidal hard-sphere fluids

Alice L Thorneywork, Dirk G A L Aarts, Juergen Horbach, and Roel P A Dullens

Phys. Rev. E 2017 95 012614

We present a systematic experimental study of the dynamic behavior of monodisperse and bidisperse twodimensional colloidal hard-sphere fluids. We consider the diffusive behavior of the two types of particles for systems with a variety of compositions and total area fractions. In particular, we measu ...

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Dynamic mode locking in a driven colloidal system: experiments and theory

Michael P N Juniper, Urs Zimmermann, Arthur V Straube, Rut Besseling, Dirk G A L Aarts, Hartmut Loewen, and Roel P A Dullens

NEW J. PHYS. 2017 19 013010

In this article we examine the dynamics of a colloidal particle driven by a modulated force over a sinusoidal optical potential energy landscape. Coupling between the competing frequencies of the modulated drive and that of particle motion over the periodic landscape leads to synchronisation of part ...

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Exploring concentration, surface area and surface chemistry effects of colloidal aggregates on fat crystal networks

Raamanand R Chauhan, Roel P A Dullens, Krassimir P Velikov, and Dirk G A L Aarts

RSC Adv. 2017 7 28780

We study the effects of concentration, surface area and surface chemistry of fractal fumed silica aggregates on a model fat-structured food system. We use oscillatory stress sweep rheology to determine the storage modulus, the length of the linear viscoelastic region and the rate of network breakdow ...

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The effect of colloidal aggregates on fat crystal networks

Raamanand R Chauhan, Roel P A Dullens, Krassimir P Velikov, and Dirk G A L Aarts

Food Funct. 2017 8 352

We investigate the role of a colloidal model system in the crystallization and network formation of lipids. This system consists of fractal fumed silica aggregates. We look at the influence of different solid fat concentrations and fumed silica concentrations on the resulting gel network. Oscillat ...

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2016

Equilibrium Grain Boundary Segregation and Clustering of Impurities in Colloidal Polycrystalline Monolayers

Francois A Lavergne, Samuel Diana, Dirk G A L Aarts, and Roel P A Dullens

LANGMUIR 2016 32 12716

We investigate the segregation of impurities to grain boundaries in colloidal polycrystalline monolayers using video microscopy. A model colloidal alloy is prepared by embedding large spherical impurities in a polycrystalline monolayer of small host colloidal hard spheres, which stops grain growth a ...

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Coordination number statistics of cluster formation

Colin P Reynolds, David Robinson, Dirk G A L Aarts, Mark Wilson, William W Sampson, and Roel P A Dullens

EPL-Europhys. Lett. 2016 116 28001

We establish a direct relation between the distribution of coordination numbers for individual particles and the mean cluster size using simple statistical considerations. We test our probabilistic theory against an experimental model system of superparamagnetic colloidal particles, which form cha ...

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Core-Shell Particles for Simultaneous 3D Imaging and Optical Tweezing in Dense Colloidal Materials

Yanyan Liu, Kazem V Edmond, Arran Curran, Charles Bryant, Bo Peng, Dirk G A L Aarts, Stefano Sacanna, and Roel P A Dullens

Adv. Mater. 2016 28 8001

A new colloidal system that consists of core-shell "probe" particles embedded in an optically transparent "host" particle suspension is developed. This system enables simultaneous fast confocal imaging and optical tweezing in dense 3D colloidal materials. ...

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Segregated Ice Growth in a Suspension of Colloidal Particles

Julia M H Schollick, Robert W Style, Arran Curran, John S Wettlaufer, Eric R Dufresne, Patrick B Warren, Krassimir P Velikov, and Roel P A Dullens

J. Phys. Chem. B 2016 120 3941

We study the freezing of a dispersion of colloidal silica particles in water, focusing on the formation of segregated ice in the form of ice lenses. Local temperature measurements in combination with video microscopy give insight into the rich variety of factors that control ice lens formation. We o ...

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Colloidal particles driven across periodic optical-potential-energy landscapes

Michael P N Juniper, Arthur V Straube, Dirk G A L Aarts, and Roel P A Dullens

Phys. Rev. E 2016 93 012608

We study the motion of colloidal particles driven by a constant force over a periodic optical potential energy landscape. First, the average particle velocity is found as a function of the driving velocity and the wavelength of the optical potential energy landscape. The relationship between average ...

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On the Gaussian approximation in colloidal hard sphere fluids

Alice L Thorneywork, Dirk G A L Aarts, Juergen Horbach, and Roel P A Dullens

Soft Matter 2016 12 4129

We study the behaviour of the self-intermediate scattering function and self-van Hove correlation function for quasi-two-dimensional colloidal hard sphere fluids at a range of area fractions. We compute these functions first directly from the particle coordinates and secondly from the mean squared d ...

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2015

Effect of Hydrodynamic Interactions on Self-Diffusion of Quasi-Two-Dimensional Colloidal Hard Spheres

Alice L Thorneywork, Roberto E Rozas, Roel P A Dullens, and Juergen Horbach

Phys. Rev. Lett. 2015 115 268301

We compare experimental results from a quasi-two-dimensional colloidal hard sphere fluid to a Monte Carlo simulation of hard disks with small particle displacements. The experimental short-time self-diffusion coefficient D-S scaled by the diffusion coefficient at infinite dilution, D-0, strongly dep ...

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Thermal Analog of Gimbal Lock in a Colloidal Ferromagnetic Janus Rod

Yongxiang Gao, Andrew K Balin, Roel P A Dullens, Julia M Yeomans, and Dirk G A L Aarts

Phys. Rev. Lett. 2015 115 248301

We report an entropy-driven orientational hopping transition in a magnetically confined colloidal Janus rod. In a magnetic field, the sedimented rod randomly hops between horizontal and vertical states: the latter state comes at a substantial gravitational cost at no reduction of magnetic potential ...

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Deterministic aggregation kinetics of superparamagnetic colloidal particles

Colin P Reynolds, Kira E Klop, Francois A Lavergne, Sarah M Morrow, Dirk G A L Aarts, and Roel P A Dullens

J. Chem. Phys. 2015 143 214903

We study the irreversible aggregation kinetics of superparamagnetic colloidal particles in two dimensions in the presence of an in-plane magnetic field at low packing fractions. Optical microscopy and image analysis techniques are used to follow the aggregation process and in particular study the pa ...

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Direct calculation of distortion energies in colloidal liquid crystals from single-particle data

Kira E Klop, Chris L Farmer, Roel P A Dullens, and Dirk G A L Aarts

Mol. Phys. 2015 113 2693

We report a method to calculate distortion energies of a colloidal liquid crystal from single-particle data via a triangulation of the particle positions followed by a linear interpolation of the particle orientations. Our method provides local information on the strength and type of distortions pre ...

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Superconfinement tailors fluid flow at microscales

Siti A Setu, Roel P A Dullens, Aurora Hernandez-Machado, Ignacio Pagonabarraga, Dirk G A L Aarts, and Rodrigo Ledesma-Aguilar

Nat. Commun. 2015 6 7297

Understanding fluid dynamics under extreme confinement, where device and intrinsic fluid length scales become comparable, is essential to successfully develop the coming generations of fluidic devices. Here we report measurements of advancing fluid fronts in such a regime, which we dub superconfinem ...

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Determining local geometrical features of grain boundaries from microscopy

Francois A Lavergne, Dirk G A L Aarts, and Roel P A Dullens

J. PHYS.-CONDENS. MAT. 2015 27 194117

Grain boundaries are solid-solid interfaces whose dynamics is driven by their local curvature. As they are fluctuating interfaces and have a width comparable to the lattice spacing of the surrounding grains, the determination of their local geometrical characteristics is difficult. Here we present a ...

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Microscopic dynamics of synchronization in driven colloids

Michael P N Juniper, Arthur V Straube, Rut Besseling, Dirk G A L Aarts, and Roel P A Dullens

Nat. Commun. 2015 6 7187

Synchronization of coupled oscillators has been scrutinized for over three centuries, from Huygens' pendulum clocks to physiological rhythms. One such synchronization phenomenon, dynamic mode locking, occurs when naturally oscillating processes are driven by an externally imposed modulation. Typical ...

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