Archive for the ‘Hot Article’ Category

Leading Article by Soft Matter 2014 Lectureship Winner

Surface tension and the mechanics of liquid inclusions in compliant solids

Robert W. Style, John S. Wettlaufer, and Eric R. Dufresne

Dufresne et al. graphical abstract

This article proposes a theory of fluid inclusions in soft solids and builds upon experimental findings of a previous paper recently published in Nature Physics – “Stiffening solids with liquid inclusions” doi:10.1038/nphys3181 – which revealed that Eshelby’s foundational theory fails to describe the mechanical response of soft composites. Eshelby’s theory of elastic inclusions is significantly cited and outlines the response of microscopic inclusions within an elastic solid when macroscopically stress is applied. Furthermore, Eshelby’s theory allows the prediction of bulk properties and is fundamental in calculating the stress field in fracture mechanics. It has been widely used in many other areas such as cell biology to predict cell interactions and seismology.

The theoretical study aims to rationalise the experimental results from the previous paper and explain that they were due to the surface tension of the solid-liquid interface, which is completely ignored in established theory.

The work expands previous theories based on strain-dependent surface stresses, relevant to nanoinclusions in stiffer materials, but not for softer materials such as gels. The group only considered isotropic loadings, used incorrect boundary conditions, or only considered incompressible solids and employed a dipole approximation to calculate composite properties.

The group adapted Eshelby’s inclusion theory so that it included surface tension for liquid inclusions in a linear elastic solid, giving both the microscopic behaviour and themacroscopic effects of inclusions in composites. The authors believe that these findings can be applied to a wide variety of soft material systems, especially composites comprising of soft materials such as gels and elastomers.

Full citation information:

Surface tension and the mechanics of liquid inclusions in compliant solids
Robert W. Style, John S. Wettlaufer and Eric R. Dufresne
Soft Matter, 2015, Advance Article
DOI: 10.1039/C4SM02413C

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HOT articles for December!

Pearling and arching instabilities of a granular suspension on a super-absorbing surface
Julien Chopin and Arshad Kudrolli

Graphical abstract: Pearling and arching instabilities of a granular suspension on a super-absorbing surface

Effects of topological constraints on globular polymers
Maxim V. Imakaev, Konstantin M. Tchourine, Sergei K. Nechaev and Leonid A. Mirny

Graphical abstract: Effects of topological constraints on globular polymers

These articles will be free until 7th January 2015


Thermodynamics of the self-assembly of non-ionic chromonic molecules using atomistic simulations. The case of TP6EO2M in aqueous solution
Anna Akinshina, Martin Walker, Mark R. Wilson, Gordon J. T. Tiddy, Andrew J. Masters and Paola Carbone

Graphical abstract: Thermodynamics of the self-assembly of non-ionic chromonic molecules using atomistic simulations. The case of TP6EO2M in aqueous solution

Graphene Oxide Single Sheets as Substrate for High Resolution cryoTEM
Marcel van de Put, Joseph P. Patterson, Paul Bomans, Neil Wilson, Heiner Friedrich, Rolf van Benthem, Gijsbertus de With, Rachel K. O’Reilly and Nico Sommerdijk 

These articles will be free until 14th January 2015


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A simple route to responsive, particle-stabilized foams using bare silica nanoparticles

Web writer Rob Woodward highlights a hot article from the journal


Defined as bubbles of gas in liquid-film matrix, foams are important precursors in the food and cosmetic industry and for the production of macroporous materials. In this report a simple, effective route to silica nanoparticle stabilised responsive aqueous foams has been demonstrated by the Binks group. Stimuli-responsive surface active particles have generated growing interest in recent years, utilising triggers including pH, temperature and light irradiation to create ‘switchable’ foams, i.e. the ability to “switch-off” the foaming capability of the particles. However, the production of responsive surface active particles usually involves surface coating of mineral particles or the complicated synthesis of functional polymer particles.

In order to address this problem Binks et al. utilise the interaction of N’-dodecyl-N,N-dimethylacetamidinium bicarbonate, a responsive surfactant, with anionic silica nanoparticles in water. By exposure to either CO2 or N2 the responsive surfactant can be switched between a cationic species and a surface-inactive neural form, respectively. On the formation of the cationic species, complexation of the surfactant to anionic silica nanoparticle surfaces gives an in situ increase in the hydrophobicity of the silica, yielding surface-active nanoparticles. Agitation of the resulting complexed system gives foams, however, on exposure to N2 the responsive surfactant returns to its neutral state and desorbs from the surface of the silica particles, resulting in desorption of the particles from the water-air interface.

This simple route to switchable particle-stabilized aqueous foams removes the need for the complicated synthesis of particles as ‘bare’ silica nanoparticles can be used. The synergistic effect of the responsive surfactant and the nanoparticles also allows for the production of foams using a much lower concentration of surfactant than in a responsive-surfactant system alone.

Micrographs of the bubbles in foams produced by shaking 10 cm3 of a dispersion of 0.5 wt% particles in a surfactant solution at different concentrations in bottles (25 cm3) taken immediately after shaking. Surfactant concentrations from A to F are: 0.1, 0.2, 0.3, 0.6, 1.0 and 2.0 mM.

To find out more read the full article:

Responsive aqueous foams stabilised by silica nanoparticles hydrophobised in situ with a switchable surfactant

Yue Zhu, Jianzhong Jiang, Zhenggang Cui and Bernie Binks

Soft Matter, 2014, Accepted Manuscript

DOI: 10.1039/C4SM01970A

This post was written by web writer Rob Woodward. Rob is currently based in Imperial College London working in the Polymer and Composite Engineering (PaCE) group. Rob has a background in both responsive polymeric surfactants and microporous organic polymers for carbon capture and storage.

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On polydispersity and the hard sphere glass transition – an overview of a hot article

On polydispersity and the hard sphere glass transition, Emanuela Zaccarelli, Siobhan M. Liddle and Wilson C. K. Poon, Soft Matter, 2014

DOI: 10.1039/C4SM02321H

The aim of this work was to investigate the dynamics of polydisperse hard spheres at high packing fractions φ. The effects of polydispersity and the detailed shape of the particle size distribution (PSD) were studied.


The glass transition is not fully understood despite many decades of research. The discovery that hard-spheres, sterically-stabilised polymethylmethacrylate (PMMA) colloids, underwent kinetic arrest at a packing fraction of φ = φg ≈ 0.58 led to hard sphere colloids becoming the preferred method to test mode coupling theory (MCT). This is a significant piece of work by Emanuela Zaccarelli, Siobhan M. Liddle and Wilson C. K. Poon who are the first to present simulations of a polydisperse system of hard spheres with a size distribution essentially identical to the experimental data. The findings of the authors are novel and very important, they also put forward a new interpretation of what is going on in glass transition of MCT experiments. Assumptions with regard to PSD are not made and a model as close to the experimental one as possible is designed.

Event-driven Molecular Dynamics (MD) simulations of hard spheres with different PSD were performed. Experimentally obtained PSD from ≈ 2200 PMMA particles were measured by transmission electron microscopy (TEM). N = 2309 particles were simulated with the experimental PSD, measurement noise was included to produce a realistic system representation. N = 2000 particles taken from Gaussian and top hat distributions were considered for comparison.

It was found that a mixed state of ergodic small particles and glassy large particles in a window of concentrations is present and results in a hybrid dynamical state that is fluid for a long time but shows an unusual type of ageing. The breakdown of the MCT-predictions is due to the existence of partial decoupling, which is not accounted for in the monodisperse-version of MCT. However, the results of MCT are recovered once the polydispersity is reduced. There is a non-monotonic dependence of the quality of the glass former on the polydispersity index, s. When s = 0, the system is prone to crystallization and strong glasses are formed when s = <8%. The glass transition is smeared out due to the emergence of the “ageing liquid” for higher values of s as well as for samples drawn from peaked distributions. The precise form of the size distribution is relevant, a peaked distribution that allows a distinction between small and large particles is essential but this is not the case in the top hat particle distribution.

In conclusion, at a fixed relative standard deviation of the PSD the exact shape of the PSD has little influence on the general behaviour of the dynamics, large differences between the dynamics of “small” and “large” particles are found for realistic PSD shapes.

The glass transition is smeared out in polydisperse hard spheres due to decoupling between small and large particles

Please follow the link for the full article.

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HOT articles for November!

Molecular geometry, twist-bend nematic phase and unconventional elasticity: a generalised
Maier–Saupe theory Cristina Greco, Geoffrey R. Luckhurst and Alberta Ferrarini 

Graphical abstract: Molecular geometry, twist-bend nematic phase and unconventional elasticity: a generalised Maier–Saupe theory

 
“Crystal-clear” liquid–liquid transition in a tetrahedral fluid
Francis W. Starr and Francesco Sciortino

Graphical abstract: “Crystal-clear” liquid–liquid transition in a tetrahedral fluid

These articles will be free until 1st December 2014


Peeling-angle dependence of the stick-slip instability during adhesive tape peeling
Marie-Julie Dalbe, Stéphane Santucci, Loïc Vanel and Pierre-Philippe Cortet  

Graphical abstract: Peeling-angle dependence of the stick-slip instability during adhesive tape peeling

Multi-blob coarse graining for ring polymer solutions
Arturo Narros, Christos N. Likos, Angel J. Moreno and Barbara Capone 

Graphical abstract: Multi-blob coarse graining for ring polymer solutions

These articles will be free until 9th  December 2014


 
Relating foam and interfacial rheological properties of β-lactoglobulin solutions
M. Lexis and N. Willenbacher

Graphical abstract: Relating foam and interfacial rheological properties of β-lactoglobulin solutions

 
Controlling mechanisms in directional growth of aggregated archaeal cells
Viktor Milkevych and Damien J. Batstone

Graphical abstract: Controlling mechanisms in directional growth of aggregated archaeal cells

These articles will be free until 16th  December 2014


Examining platelet adhesion via Stokes flow simulations and microfluidic experiments
Sean Fitzgibbon, Jonathan Cowman, Antonio J. Ricco, Dermot Kenny and Eric S. G. Shaqfeh

Graphical abstract: Examining platelet adhesion via Stokes flow simulations and microfluidic experiments
Sequential phase transformation of propeller-like C3-symmetric liquid crystals from a helical to ordered to disordered hexagonal columnar structure
Soyoung Park and Byoung-Ki Cho

Graphical abstract: Sequential phase transformation of propeller-like C3-symmetric liquid crystals from a helical to ordered to disordered hexagonal columnar structure

These articles will be free until 23rd  December 2014


Hierarchical superstructures from a star-shaped molecule consisting of a cyclic oligosiloxane with cyanobiphenyl moieties Dae-Yoon Kim, Minwook Park, Sang-A Lee, Soeun Kim, Chih-Hao Hsu, Namil Kim, Shiao-Wei Kuo, Tae-Ho Yoon and Kwang-Un Jeong

Graphical abstract: Hierarchical superstructures from a star-shaped molecule consisting of a cyclic oligosiloxane with cyanobiphenyl moieties

These articles will be free until 30th  December 2014


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Block Copolymer Spheres or Block Copolymer Worms: Which Pickering Emulsifier Has More Backbone?

This recent publication from the Armes group investigates the ability of a number of amphiphilic block copolymer nanoparticles to stabilize n-dodecane-in-water emulsions. The aim of the work was to compare spherical and worm-like nano-structures and their efficiency as Pickering emulsifiers, i.e. the ability of these solid particles to adsorb irreversibly at the liquid-liquid interface to form a Pickering emulsion.

Graphical abstract: Are block copolymer worms more effective Pickering emulsifiers than block copolymer spheres?

In previous work by the University of Sheffield group, a number of both linear and branched block copolymers were produced in the form of vesicular structures. It was found that branching was necessary in order to prevent the vesicles dissociating into individual copolymer chains when exposed to high-shear homogenization. In this work linear and branched analogues of the copolymer poly(glycerol monomethacrylate)–poly(2-hydroxypropyl methacrylate) (PGMA-PHPMA) are synthesized as both spherical and worm-like nanoparticles. Armes et al. report that the linear nano-structures are not sufficiently robust enough to survive the high-shear conditions necessary for emulsification, whereas the cross-linked copolymer structures are more likely to retain their morphologies and yield genuine Pickering emulsions. Spherical and worm-like structures are provided greater covalent stabilization via chemical cross-linking, allowing structures to survive homogenization as with the vesicles reported previously.

The use of the more hydrophobic poly(benzyl methacrylate) (PBzMA) in place of PHPMA was also investigated in order to examine if increased amphiphilicity could enhance the stability of linear nano-objects in the absence of chemical cross-linking. Both the spherical and worm-like structures comprised of these linear polymer chains formed stable Pickering emulsions, suggesting that branching is not mandatory for the formation of the particulate surfactants.

Due to strong adsorption at the liquid-liquid interface and their ability to produce smaller droplets at a given nanoparticle concentration, it is concluded that branched copolymers with worm-like morphologies are the more effective Pickering emulsifiers. This is also aided by the suggestion that they are at least as efficiently adsorbed at the interface as their spherical analogues.

K. L. Thompson, C. J. Mable, A. Cockram, N. J. Warren, V. J. Cunningham, E. R. Jones, R. Verber and S. P. Armes

This post was written by web writer Rob Woodward. Rob is currently based in Imperial College London working in the Polymer and Composite Engineering (PaCE) group. Rob has a background in both responsive polymeric surfactants and microporous organic polymers for carbon capture and storage.

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HOT articles for October!

 
Magneto-optic and converse magnetoelectric effects in a ferromagnetic liquid crystal
Alenka Mertelj, Natan Osterman, Darja Lisjak and Martin Čopič 

 Graphical abstract: Magneto-optic and converse magnetoelectric effects in a ferromagnetic liquid crystal
 
Trajectories of probe spheres in generalized linear viscoelastic complex fluids
Manas Khan and Thomas G. Mason  

Graphical abstract: Trajectories of probe spheres in generalized linear viscoelastic complex fluids

These articles will be free until 29th October 2014


Capillary tube wetting induced by particles: towards armoured bubbles tailoring
Farzam Zoueshtiagh, Michael Baudoin and David Guerrin

Graphical abstract: Capillary tube wetting induced by particles: towards armoured bubbles tailoring

 
Measuring cellular forces using bis-aliphatic hydrazone crosslinked stress-relaxing hydrogels
D. D. McKinnon, D. W. Domaille, T. E. Brown, K. A. Kyburz, E. Kiyotake, J. N. Cha and K. S. Anseth

Graphical abstract: Measuring cellular forces using bis-aliphatic hydrazone crosslinked stress-relaxing hydrogels

These articles will be free until 13th November 2014


Chiral random grain boundary phase of achiral hockey-stick liquid crystals
Dong Chen, Haitao Wang, Min Li, Matthew A. Glaser, Joseph E. Maclennan and Noel A. Clark

Graphical abstract: Chiral random grain boundary phase of achiral hockey-stick liquid crystals
 
Self-assembly of hard helices: a rich and unconventional polymorphism
Hima Bindu Kolli, Elisa Frezza, Giorgio Cinacchi, Alberta Ferrarini, Achille Giacometti, Toby S. Hudson, Cristiano De Michele and Francesco Sciortino

Graphical abstract: Self-assembly of hard helices: a rich and unconventional polymorphism

These articles will be free until 19th November 2014


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HOT articles for September!

Engineering entropy in soft matter: the bad, the ugly and the good
Fernando A. Escobedo 

Graphical abstract: Engineering entropy in soft matter: the bad, the ugly and the good

3D Viscoelastic traction force microscopy
Jennet Toyjanova, Erin Hannen, Eyal Bar-Kochba, Eric M. Darling, David L. Henann and Christian Franck

Graphical abstract: 3D Viscoelastic traction force microscopy

These articles will be free until 10th October 2014


 
Approach to universal self-similar attractor for the levelling of thin liquid films
Michael Benzaquen, Paul Fowler, Laetitia Jubin, Thomas Salez, Kari Dalnoki-Veress and Elie Raphaël  

Graphical abstract: Approach to universal self-similar attractor for the levelling of thin liquid films
 
Discovery of a tetracontinuous, aqueous lyotropic network phase with unusual 3D-hexagonal symmetry
Gregory P. Sorenson, Adam K. Schmitt and Mahesh K. Mahanthappa  

Graphical abstract: Discovery of a tetracontinuous, aqueous lyotropic network phase with unusual 3D-hexagonal symmetry

These articles will be free until 15th October 2014


Extracting the dynamic correlation length of actin networks from microrheology experiments
Adar Sonn-Segev, Anne Bernheim-Groswasser and Yael Roichman

Graphical abstract: Extracting the dynamic correlation length of actin networks from microrheology experiments

Tuning the surface properties of hydrogel at the nanoscale with focused ion irradiation
Y. Kim, A. Y. Abuelfilat, S. P. Hoo, A. Al-Abboodi, B. Liu, Tuck Ng, P. Chan and J. Fu  

Graphical abstract: Tuning the surface properties of hydrogel at the nanoscale with focused ion irradiation 
 

These articles will be free until 22nd  October 2014


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HOT articles for August!

Thermal transitions in hydrated layer-by-layer assemblies observed using electrochemical impedance spectroscopy
Choonghyun Sung, Katelin Hearn and Jodie Lutkenhaus

Graphical abstract: Thermal transitions in hydrated layer-by-layer assemblies observed using electrochemical impedance spectroscopy


Structural and mechanical characteristics of polymersomes
Hung-Yu Chang, Yu-Jane Sheng and Heng-Kwong Tsao

Graphical abstract: Structural and mechanical characteristics of polymersomes

These articles are free to access until 5th September 2014

 


Crystallizing hard-sphere glasses by doping with active particles
Ran Ni, Martien A. Cohen Stuart, Marjolein Dijkstra and Peter G. Bolhuis  

Graphical abstract: Crystallizing hard-sphere glasses by doping with active particles

Phase transitions in supported lipid bilayers studied by AFM
Andrea Alessandrini and Paolo Facci

Graphical abstract: Phase transitions in supported lipid bilayers studied by AFM

These articles are free to access until 11th September 2014


Prediction and validation of diffusion coefficients in a model drug delivery system using microsecond atomistic molecular dynamics simulation and vapour sorption analysis
Christopher Forrey, David M. Saylor, Joshua S. Silverstein, Jack F. Douglas, Eric M. Davis and Yossef A. Elabd

Graphical abstract: Prediction and validation of diffusion coefficients in a model drug delivery system using microsecond atomistic molecular dynamics simulation and vapour sorption analysis

 
Biobased building blocks for the rational design of renewable block polymers
Angela L. Holmberg, Kaleigh H. Reno, Richard P. Wool and Thomas H. Epps, III 

Graphical abstract: Biobased building blocks for the rational design of renewable block polymers

These articles are free to access until 18th September 2014


 
Highly ordered 2D microgel arrays: compression versus self-assembly
Karen Geisel, Walter Richtering and Lucio Isa  

Graphical abstract: Highly ordered 2D microgel arrays: compression versus self-assembly
Evidence for equilibrium gels of valence-limited particles
Nikola A. Dudukovic and Charles F. Zukoski

Graphical abstract: Evidence for equilibrium gels of valence-limited particles

These articles are free to access until 25th September 2014


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HOT articles for July!

Capillary bridge rupture in dip-pen nanolithography
Daniel J. Eichelsdoerfer, Keith A. Brown and Chad A. Mirkin  

 Graphical abstract: Capillary bridge rupture in dip-pen nanolithography
 
A universal scaling law of grain chain elasticity under pressure revealed by a simple force vibration method
Lichen Chai, Xuebang Wu and C. S. Liu    

Graphical abstract: A universal scaling law of grain chain elasticity under pressure revealed by a simple force vibration method

These papers are free to access until 3rd August 2014


Growth of equilibrium structures built from a large number of distinct component types
Lester O. Hedges, Ranjan V. Mannige and Stephen Whitelam   

 Graphical abstract: Growth of equilibrium structures built from a large number of distinct component types

Branched–linear polyion complexes investigated by Monte Carlo simulations
Daniel G. Angelescu and Per Linse  

Graphical abstract: Branched–linear polyion complexes investigated by Monte Carlo simulations

 
The adsorption–desorption behaviour and structure function relationships of bile salts
Roger Parker, Neil M. Rigby, Michael J. Ridout, A. Patrick Gunning and Peter J. Wilde  
Graphical abstract: The adsorption–desorption behaviour and structure function relationships of bile salts

Tiling patterns from ABC star molecules: 3-colored foams?
Jacob J. K. Kirkensgaard, Martin C. Pedersen and Stephen T. Hyde  
Graphical abstract: Tiling patterns from ABC star molecules: 3-colored foams?

These papers are free to access until 21st  August 2014


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