Patrick B. Warren
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View article: Predicting Critical Micelle Concentrations from Short Time Scale Simulations
Predicting Critical Micelle Concentrations from Short Time Scale Simulations Open
The determination of surfactant critical micelle concentrations (CMCs) using molecular simulations is by now a well-established procedure. The approach typically utilizes the equilibrium free surfactant concentration (i.e., those surfactan…
View article: A dataset for aqueous surfactant phase behavior as a function of temperature and composition
A dataset for aqueous surfactant phase behavior as a function of temperature and composition Open
Presented here is a dataset (PhDat) discretizing the aqueous phase behavior of 143 surfactants as a function of temperature and composition. Across the complete dataset, we classify the discretized state points into 118 distinct possible p…
View article: Charging Dynamics of Electric Double-Layer Nanocapacitors in Mean Field
Charging Dynamics of Electric Double-Layer Nanocapacitors in Mean Field Open
An electric double-layer capacitor (EDLC) stores energy by modulating the spatial distribution of ions in the electrolytic solution that it contains. We determine the mean-field timescales for planar EDLC relaxation to equilibrium after a …
View article: Poisson-Nernst-Planck charging dynamics of an electric double-layer capacitor: Symmetric and asymmetric binary electrolytes
Poisson-Nernst-Planck charging dynamics of an electric double-layer capacitor: Symmetric and asymmetric binary electrolytes Open
A parallel plate capacitor containing an electrolytic solution is the simplest model of a supercapacitor or electric double-layer capacitor. Using both analytical and numerical techniques, we solve the Poisson-Nernst-Planck equations for s…
View article: Modeling Contact Angles with Chemically Specific Dissipative Particle Dynamics
Modeling Contact Angles with Chemically Specific Dissipative Particle Dynamics Open
We explore how walls can be introduced into chemically specific dissipative particle dynamics models such that the surface energies can be chosen to obtain a desired contact angle on a given substrate, for example, for an oil/water interfa…
View article: Diffusive evaporation dynamics in polymer solutions is ubiquitous
Diffusive evaporation dynamics in polymer solutions is ubiquitous Open
A phase field model predicts the ubiquitous nature of diffusion-limited evaporation (DLE) in polymer solutions, resulting from the formation of high-concentration polymer layer at the solution–air interface, here shown for the two-dimensio…
View article: Renormalisation group theory applied to $\ddot{x}+\dot{x}+x^2=0$
Renormalisation group theory applied to $\ddot{x}+\dot{x}+x^2=0$ Open
The titular ordinary differential equation (ODE) is encountered in the theory of on-axis inertial particle capture by a blunt stationary collector at a viscous-flow stagnation point. Phase space for the ODE divides into two attractor basin…
View article: Coarse-grained polarizable soft solvent models, with applications in dissipative particle dynamics
Coarse-grained polarizable soft solvent models, with applications in dissipative particle dynamics Open
We critically examine a broad class of explicitly polarizable soft solvent models aimed at applications in dissipative particle dynamics. We obtain the dielectric permittivity using the fluctuating box dipole method in linear response theo…
View article: Coarse-grained polarizable soft solvent models, with applications in dissipative particle dynamics
Coarse-grained polarizable soft solvent models, with applications in dissipative particle dynamics Open
We critically examine a broad class of explicitly polarizable soft solvent models aimed at applications in dissipative particle dynamics. We obtain the dielectric permittivity using the fluctuating box dipole method in linear response theo…
View article: Salt solutions with two or more salts generate ion currents analogous to magnetic field lines
Salt solutions with two or more salts generate ion currents analogous to magnetic field lines Open
A gradient of a single salt in a solution generates an electric field, but not a current. Recent theoretical work by one of us [Phys. Rev. Lett. 24, 248004 (2020)] showed that the Nernst-Planck equations imply that crossed gradients of two…
View article: Modelling contact angles with chemically specific dissipative particle dynamics
Modelling contact angles with chemically specific dissipative particle dynamics Open
We explore how walls can be introduced into chemically-specific dissipative particle dynamics (DPD) models such that the surface energies can be chosen to obtain a desired contact angle on a given substrate, for example for an oil/water in…
View article: Simulating micelle self-assembly to assess potential for viscosity build in surfactant formulations
Simulating micelle self-assembly to assess potential for viscosity build in surfactant formulations Open
Self-assembly of surfactants into complex structures is key to the performance of many formulated products, which form a significant fraction of the world’s manufactured goods. Here we adopt the dissipative particle dynamics simulation app…
View article: Colloidal diffusiophoresis in crossed electrolyte gradients: Experimental demonstration of an “action-at-a-distance” effect predicted by the Nernst-Planck equations
Colloidal diffusiophoresis in crossed electrolyte gradients: Experimental demonstration of an “action-at-a-distance” effect predicted by the Nernst-Planck equations Open
In an externally imposed electrolyte (salt) concentration gradient, charged colloids drift at speeds of order one micrometre per second. This phenomenon is known as diffusiophoresis. In systems with multiple salts and “crossed” salt gradie…
View article: Diffusive evaporation dynamics in polymer solutions is ubiquitous
Diffusive evaporation dynamics in polymer solutions is ubiquitous Open
Recent theory and experiments have shown how the buildup of a high-concentration polymer layer at a one-dimensional solvent-air interface can lead to an evaporation rate that scales with time as $t^{-1/2}$ and that is insensitive to the am…
View article: Colloidal diffusiophoresis in crossed electrolyte gradients: experimental demonstration of an 'action at a distance' effect predicted by the Nernst-Planck equations
Colloidal diffusiophoresis in crossed electrolyte gradients: experimental demonstration of an 'action at a distance' effect predicted by the Nernst-Planck equations Open
In an externally imposed electrolyte (salt) concentration gradient, charged colloids drift at speeds of order one micrometre per second. This phenomenon is known as diffusiophoresis. In systems with multiple salts and 'crossed' salt gradie…
View article: Simulating micelle self-assembly to assess potential for viscosity build in surfactant formulations
Simulating micelle self-assembly to assess potential for viscosity build in surfactant formulations Open
Self-assembly of surfactants into complex structures is key to the performance of many formulated products, which form a significant fraction of the world’s manufactured goods. Here we adopt the dissipative particle dynamics simulation app…
View article: Critical inertia for particle capture is determined by surface geometry at forward stagnation point
Critical inertia for particle capture is determined by surface geometry at forward stagnation point Open
Aerosols are ubiquitous, and particle capture from particle-laden air as it flows past an obstacle is of widespread practical importance. Neglecting diffusion, previous work has shown that for a smooth curved surface in both Stokes flow an…
View article: Anomalous Scaling for Hydrodynamic Lubrication of Conformal Surfaces
Anomalous Scaling for Hydrodynamic Lubrication of Conformal Surfaces Open
The hydrodynamic regime of the Stribeck curve giving the friction coefficient $μ$ as a function of the dimensionless relative sliding speed (the Sommerfeld number, $S$) of two contacting non-conformal surfaces is usually considered trivial…
View article: Gap-Dependent Hydrodynamic Lubrication in Conformal Contacts
Gap-Dependent Hydrodynamic Lubrication in Conformal Contacts Open
We show that the hydrodynamic lubrication of contacting conformal surfaces with a typical texture height gives rise to a universal behaviour in the Stribeck curve in which the friction coefficient shows an anomalous power-law dependence on…
View article: Methods of particle manipulation and analysis
Methods of particle manipulation and analysis Open
Methods described herein, in some embodiments, permit extraction of particle structural and/or surface charge data from gradient induced particle motion in channels. In one aspect, a method of manipulating particle motion comprises introdu…
View article: Can Machine Learning Predict the Phase Behavior of Surfactants?
Can Machine Learning Predict the Phase Behavior of Surfactants? Open
[Image: see text] We explore the prediction of surfactant phase behavior using state-of-the-art machine learning methods, using a data set for twenty-three nonionic surfactants. Most machine learning classifiers we tested are capable of fi…
View article: Partial osmotic pressures of ions in electrolyte solutions and the Gibbs-Guggenheim uncertainty principle
Partial osmotic pressures of ions in electrolyte solutions and the Gibbs-Guggenheim uncertainty principle Open
The concept of the partial osmotic pressure of ions in an electrolyte solution is critically examined. In principle these can be defined by introducing a solvent-permeable wall and measuring the force per unit area which can certainly be a…
View article: Poisson-Nernst-Planck charging dynamics of an electric double layer capacitor: symmetric and asymmetric binary electrolytes
Poisson-Nernst-Planck charging dynamics of an electric double layer capacitor: symmetric and asymmetric binary electrolytes Open
A parallel plate capacitor containing an electrolytic solution is the simplest model of a supercapacitor, or electric double layer capacitor. Using both analytical and numerical techniques, we solve the Poisson-Nernst-Planck equations for …
View article: Can machine learning predict the phase behavior of surfactants?
Can machine learning predict the phase behavior of surfactants? Open
We explore the prediction of surfactant phase behavior using state-of-the-art machine learning methods, using a data set for twenty-three non-ionic surfactants in line with Bell, Phil. Trans. R. Soc. A 2016, 374, 20150137. Most machine lea…
View article: Phase Behavior of Alkyl Ethoxylate Surfactants in a Dissipative Particle Dynamics Model
Phase Behavior of Alkyl Ethoxylate Surfactants in a Dissipative Particle Dynamics Model Open
We present a dissipative particle dynamics (DPD) model capable of capturing the liquid state phase behavior of nonionic surfactants from the alkyl ethoxylate (CnEm) family. The model is based upon our recent work [Anderson et al. J. Chem. …
View article: Charging dynamics of electric double layer nanocapacitors in mean-field
Charging dynamics of electric double layer nanocapacitors in mean-field Open
An electric double layer capacitor (EDLC) stores energy by modulating the spatial distribution of ions in the electrolytic solution that it contains. We determine the mean-field time scales for planar EDLC relaxation to equilibrium, after …
View article: Data in support of "Colloidal diffusiophoresis in crossed electrolyte gradients: experimental demonstration of an `action at a distance' effect predicted by the Nernst-Planck equations"
Data in support of "Colloidal diffusiophoresis in crossed electrolyte gradients: experimental demonstration of an `action at a distance' effect predicted by the Nernst-Planck equations" Open
Experimental and modeling data used in the article "Colloidal diffusiophoresis in crossed electrolyte gradients: experimental demonstration of an `action at a distance' effect predicted by the Nernst-Planck equations" by Ian Williams, Patr…
View article: Data in support of "Colloidal diffusiophoresis in crossed electrolyte gradients: experimental demonstration of an `action at a distance' effect predicted by the Nernst-Planck equations"
Data in support of "Colloidal diffusiophoresis in crossed electrolyte gradients: experimental demonstration of an `action at a distance' effect predicted by the Nernst-Planck equations" Open
Experimental and modeling data used in the article "Colloidal diffusiophoresis in crossed electrolyte gradients: experimental demonstration of an `action at a distance' effect predicted by the Nernst-Planck equations" by Ian Williams, Patr…
View article: Can machine learning predict the phase behavior of surfactants?
Can machine learning predict the phase behavior of surfactants? Open
We explore the prediction of surfactant phase behavior using state-of-the-art machine- learning methods, using a data set for twenty-three non-ionic surfactants modified from Bell, Phil. Trans. R. Soc. A 2016, 374, 20150137. We recover Bel…
View article: Phase Behaviour of Alkyl Ethoxylate Surfactants in a Dissipative Particle Dynamics Model
Phase Behaviour of Alkyl Ethoxylate Surfactants in a Dissipative Particle Dynamics Model Open
We present a dissipative particle dynamics (DPD) model capable of capturing the liquid state phase behaviour of non-ionic surfactants from the alkyl ethoxylate (CnEm) family. The model is based upon our recent work [Anderson et al., J. Che…