Tag: Marcel Rey

Versatile strategy for homogeneous drying of dispersed particles
Marcel Rey,
UK COLLOIDS 2023
Date: 17 July 2023
Time: 11:20 (CET)

After spilling coffee, a tell-tale stain is left by the drying droplet. This universal phenomenon, known as the “coffee ring effect”, is observed independent of the dispersed material. However, for many technological processes such as coating techniques and ink-jet printing a uniform particle deposition is required and the coffee ring effect is a major drawback.
Here, we present a simple and versatile strategy to achieve homogeneous drying patterns by modifying the surface of the dispersed particles with surface-active polymers. A particle dispersion is mixed with excess surface-active polymers (e.g. polyvinyl alcohol). The polymer partially adsorbs onto the particles and excess polymer is removed by centrifugation and redispersion. While pure particle dispersions form a typical coffee ring, the polymer-modified dispersions dry into a uniform particle deposit. In this talk, I will discuss how the polymer coating prevents accumulation and pinning at the droplet edge and leads to a uniform particle deposition after drying.
It should be highlighted that the presented method is independent of particle shape (e.g. spherical, ellipsoidal or ill-defined particle shapes) and is applicable to a variety of commercial pigment particles (e.g. hematite, goethite or titanium dioxide). Further, the method works for different dispersion media (e.g. aqueous, polar and apolar solvents), demonstrating the practicality of this work for everyday processes.

Complex self-assembly / Overcoming the coffee ring effect
Marcel Rey
Presentation for the School of Materials at the University of Manchester
Date: 20 July 2023

In this seminar, I will talk about complex self-assembly behaviour of simple building blocks. Afterwards, I will introduce a simple yet versatile strategy to overcome the coffee ring effect and obtain homogeneous drying of particle dispersions.

Spherical colloidal particles confined at liquid interfaces typically self-assemble into hexagonal packing. Here, I will show that much more complex self-assembly behaviour is possible spherical particles with a hard-core / soft-shell architecture. Upon compression, these core-shell particles transition from a hexagonal packing to a chain packing, then to a square packing and finally to a hexagonal close packing. I will rationalize these experimental observations with calculations and simulations using simple core-shell potentials.

After spilling coffee, a tell-tale circular stain is left by the drying droplet. This universal phenomenon, known as the “coffee ring effect”, is observed independent of the suspended material. We recently developed a simple yet versatile strategy to achieve homogeneous drying of dispersed particles. Modifying the particle surface with surface-active polymers provides enhanced steric stabilization and facilitates adsorption to the liquid/air interface which, after drying, leads to uniform particle deposition. This method is independent of particle size and shape and applicable to a variety of commercial pigment particles promising applications in daily life.

 

Optical characterisation of soft microgels
Marcel Rey,
DINAMO 2023
Date: 13 June 2023
Time: 19:00 (CET)

Soft microgels are ideal model systems due to their ability to deform and adapt their shape upon external stimuli. Here, we use optical tweezers to measure the diffusion of soft core-shell microgels. We report an anomalous, subdiffusive behaviour, which may be linked to the multiple length scales present within core-shell microgels.

Marcel Rey got invited to present his recent work on stimuli-responsive emulsions and the coffee ring effect at in the group seminar of the Laboratory of Surface and Interface at the University of Granada.

In the seminar, Marcel Rey talked about his recent advances on understanding the behaviour of stimuli-responsive emulsions and afterwards introduced a simple yet versatile strategy to overcome the coffee ring effect and obtain homogeneous drying of particle dispersions.

Temperature-responsive emulsions combine the long-term stability with controlled on-demand release of the encapsulated liquid. The destabilization has previously been attributed to microgel shrinkage, leading to a lower surface coverage which induces coalescence. We demonstrated that breaking mechanism is fundamentally different than previously thought. Breaking only occurs if the stabilizing soft microgel particles assume a characteristic double-corona microstructure, which serve as weak link enabling stimuli-responsive emulsion behavior. Conversely, emulsions stabilized by regular single-corona microgels remain remarkably insensitive to temperature.

After spilling coffee, a tell-tale circular stain is left by the drying droplet. This universal phenomenon, known as the “coffee ring effect”, is observed independent of the suspended material. We recently developed a simple yet versatile strategy to achieve homogeneous drying of dispersed particles. Modifying the particle surface with surface-active polymers provides enhanced steric stabilization and facilitates adsorption to the liquid/air interface which, after drying, leads to uniform particle deposition. This method is independent of particle size and shape and applicable to a variety of commercial pigment particles promising applications in daily life.

Versatile strategy for homogeneous drying of dispersed particles
Marcel Rey,
Submitted to ISMC 2022
Date: 7 October 2022
Time: 11:20 (CET)

After spilling coffee, a tell-tale stain is left by the drying droplet. This universal phenomenon, known as the “coffee ring effect”, is observed independent of the dispersed material. However, for many technological processes such as coating techniques and ink-jet printing a uniform particle deposition is required and the coffee ring effect is a major drawback.
Here, we present a simple and versatile strategy to achieve homogeneous drying patterns by modifying the surface of the dispersed particles with surface-active polymers. A particle dispersion is mixed with excess surface-active polymers (e.g. polyvinyl alcohol). The polymer partially adsorbs onto the particles and excess polymer is removed by centrifugation and redispersion. While pure particle dispersions form a typical coffee ring, the polymer-modified dispersions dry into a uniform particle deposit. In this talk, I will discuss how the polymer coating prevents accumulation and pinning at the droplet edge and leads to a uniform particle deposition after drying.
It should be highlighted that the presented method is independent of particle shape (e.g. spherical, ellipsoidal or ill-defined particle shapes) and is applicable to a variety of commercial pigment particles (e.g. hematite, goethite or titanium dioxide). Further, the method works for different dispersion media (e.g. aqueous, polar and apolar solvents), demonstrating the practicality of this work for everyday processes.

Versatile strategy for homogeneous drying of dispersed particles
Marcel Rey,
Submitted to ISMC 2022
Date: 28 September 2022
Time: 11:20 (CET)

After spilling coffee, a tell-tale stain is left by the drying droplet. This universal phenomenon, known as the “coffee ring effect”, is observed independent of the dispersed material. However, for many technological processes such as coating techniques and ink-jet printing a uniform particle deposition is required and the coffee ring effect is a major drawback.
Here, we present a simple and versatile strategy to achieve homogeneous drying patterns by modifying the surface of the dispersed particles with surface-active polymers. A particle dispersion is mixed with excess surface-active polymers (e.g. polyvinyl alcohol). The polymer partially adsorbs onto the particles and excess polymer is removed by centrifugation and redispersion. While pure particle dispersions form a typical coffee ring, the polymer-modified dispersions dry into a uniform particle deposit. In this talk, I will discuss how the polymer coating prevents accumulation and pinning at the droplet edge and leads to a uniform particle deposition after drying.
It should be highlighted that the presented method is independent of particle shape (e.g. spherical, ellipsoidal or ill-defined particle shapes) and is applicable to a variety of commercial pigment particles (e.g. hematite, goethite or titanium dioxide). Further, the method works for different dispersion media (e.g. aqueous, polar and apolar solvents), demonstrating the practicality of this work for everyday processes.

Versatile strategy for homogeneous drying of dispersed particles
Marcel Rey, Johannes Walter, Johannes Harrer, Carmen Morcillo Perez, Salvatore Chiera, Sharanya Nair, Maret Ickler, Alesa Fuchs, Mark Michaud, Maximilian J. Uttinger, Andrew B. Schofield, Job H. J. Thijssen, Monica Distaso, Wolfgang Peukert, Nicolas Vogel
Submitted to ISMC 2022
Date: 23 September 2022
Time: 12:10 (CET)

After spilling coffee, a tell-tale stain is left by the drying droplet. This universal phenomenon, known as the “coffee ring effect”, is observed independent of the dispersed material. However, for many technological processes such as coating techniques and ink-jet printing a uniform particle deposition is required and the coffee ring effect is a major drawback.
Here, we present a simple and versatile strategy to achieve homogeneous drying patterns by modifying the surface of the dispersed particles with surface-active polymers. A particle dispersion is mixed with excess surface-active polymers (e.g. polyvinyl alcohol). The polymer partially adsorbs onto the particles and excess polymer is removed by centrifugation and redispersion. While pure particle dispersions form a typical coffee ring, the polymer-modified dispersions dry into a uniform particle deposit. In this talk, I will discuss how the polymer coating prevents accumulation and pinning at the droplet edge and leads to a uniform particle deposition after drying.
It should be highlighted that the presented method is independent of particle shape (e.g. spherical, ellipsoidal or ill-defined particle shapes) and is applicable to a variety of commercial pigment particles (e.g. hematite, goethite or titanium dioxide). Further, the method works for different dispersion media (e.g. aqueous, polar and apolar solvents), demonstrating the practicality of this work for everyday processes.