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Heterogenous nucleation and crystal growth of colloidal model-systems on curved surfaces

English title Heterogenous nucleation and crystal growth of colloidal model-systems on curved surfaces
Applicant Gasser Urs
Number 153050
Funding scheme Project funding (Div. I-III)
Research institution Paul Scherrer Institut
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Condensed Matter Physics
Start/End 01.08.2014 - 31.07.2018
Approved amount 299'070.00
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All Disciplines (2)

Discipline
Condensed Matter Physics
Physical Chemistry

Keywords (7)

crystal nucleation; phase transitions; microscopy; colloids; microgels; scattering; hard spheres

Lay Summary (German)

Lead
Die Entstehung von Kristallen in Flüssigkeiten oder Gasen (homogene Kristallbildung) oder auf Substraten (heterogene Kristallbildung) wird schon seit Jahrzehnten untersucht. Unter vielen thermodynamischen Bedingungen ist die Kristallbildung unterdrückt, da die Bildung kleiner Kristallkeime energetisch ungünstig ist. Aufgrund der Inkompatibilität des flüssigen oder gasförmigen mit dem kristallinen Zustand, muss eine Energiebarriere überwunden werden, um Kristallkeime zu bilden, die zu grossen Kristalliten weiter wachsen können.Die initiale Bildung der kleinsten Kristallkeime ist allerdings noch immer nicht gut verstanden, was sich in grossen Unterschieden zwischen gemessenen und berechneten Kristall-Bildungsraten widerspiegelt. Deshalb sind direkte Untersuchungen der Bildung der kleinsten Kristallkeime von grossem Interesse, um einen detaillierten Einblick in den Bildungsprozess der Kristallkeime zu erhalten.
Lay summary

In diesem Projekt wird die heterogene Kristallbildung in kolloidalen Suspensionen (Teilchen im Nano- oder Mikrometerbereich in Lösung) auf gekrümmten Oberflächen untersucht. Kolloidale Suspensionen sind experimentell besonders zugänglich und erlauben es, die Bildung kleinster Kristallkeime direkt zu verfolgen. Die Kristallbildung auf Oberflächen ist für Anwendungen besonders interessant, da sie eine Kontrolle über den Kristallisationsprozess ermöglichen. Der Einfluss der Krümmung des Substrats wird systematisch untersucht, um einerseits den Übergang von einer Behinderung der Kristallisation bei starker Krümmung zu einer Bevorzugung der Kristallisation auf flachen Substraten zu studieren und andererseits um den Einfluss von Oberflächen mit positiver und negativer Krümmung als Funktion des Krümmungsgrades zu verglichen. Die Untersuchungen werden mit kugelförmigen und Torus-förmigen Substraten durchgeführt. Für mögliche Anwendungen sollen Substrate mit besonders guten Eigenschaften für die Kontrolle der Kristallbildung identifiziert werden.


Direct link to Lay Summary Last update: 23.06.2014

Responsible applicant and co-applicants

Employees

Publications

Publication
Phase behavior of binary and polydisperse suspensions of compressible microgels controlled by selective particle deswelling
Scotti Andrea, Gasser Urs, Herman E.S., Han Jun, Menzel A., Lyon L.A., Fernandez-Nieves Alberto (2017), Phase behavior of binary and polydisperse suspensions of compressible microgels controlled by selective particle deswelling, in Phys. Rev. E, 96(3), 032609.
The role of ions in the self-healing behavior of soft particle suspensions
Scotti Andrea, Gasser Urs, Herman Emily S., Pelaez-Fernandez Miguel, Han Jun, Menzel Andreas, Lyon L. Andrew, Fernandez-Nieves Alberto (2016), The role of ions in the self-healing behavior of soft particle suspensions, in PNAS, 113, 1516011113.
The CONTIN algorithm and its application to determine the size distribution of microgel suspensions
Scotti Andrea, Liu W., Hyatt J.S., Herman E.S., Choi H.S., Kim J.W., Lyon L.A., Gasser Urs, Fernandez-Nieves Alberto (2015), The CONTIN algorithm and its application to determine the size distribution of microgel suspensions, in The Journal of Chemical Physics, 142, 234905.

Collaboration

Group / person Country
Types of collaboration
Soft Condensed Matter Laboratory of Prof. A. Fernandez-Nieves, School of Physics, GaTech, Atlanta GA United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
APS March Meeting Talk given at a conference Phase behavior in polydisperse microgel suspensions controlled by spontaneous particle deswelling 05.03.2018 Los Angeles CA, United States of America Gasser Urs;
Swiss Soft Day Poster Spontaneous reduction of polydispersity and self-healing colloidal crystals 02.03.2018 Paul Scherrer Institut, Villigen, Switzerland Gasser Urs;
Swiss Soft Day Poster Exploring toroidal seeds for nucleation anc crystal growth experiments 02.03.2018 Paul Scherrer Institut, Villigen, Switzerland Blatman Daniel;
SPS meeting Poster Self-healing colloidal crystals: why soft microgel particles feel the squeeze 22.08.2017 CERN, Geneva, Switzerland Gasser Urs;
Liquids conference 2017 Poster Exploring toroidal seeds for nucleation and crystal growth experiments 17.07.2017 Ljubljana, Slovenia Blatman Daniel;
Swiss Soft Day 17 Poster Self-healing colloidal crystals: why soft microgel particles feel the squeeze 30.03.2017 Zurich, Switzerland Gasser Urs;
APS March Meeting Talk given at a conference Self-healing colloidal crystals: why soft microgel particles feel the squeeze 13.03.2017 New Orleans, United States of America Gasser Urs;
Swiss Soft Day Poster Self-healing colloidal crystals: why soft microgel particles feel the squeeze 02.09.2016 Basel, Switzerland Gasser Urs;
ECM-30, European Crystallographic Meeting Poster Spontaneous reduction of polydispersity and self-healing colloidal crystals 28.08.2016 Basel, Switzerland Gasser Urs;
90th ACS Colloid and Surface Science Symposium Talk given at a conference Self-healing colloids: Why soft microgles feel the squeeze 05.06.2016 Cambridge MA, United States of America Gasser Urs;
Invited seminar talk Individual talk Self-healing colloids: Why soft microgels feel the squeeze 31.05.2016 Konstanz, Germany Gasser Urs;
Materials Day Poster Self-Healing Colloidal Crystals: Why Soft Particles Feel the Squeeze 25.11.2015 ETH Zurich, Switzerland Gasser Urs;
European Conference on Neutron Scattering Poster Self-Healing Colloidal Crystals: Why Soft Particles Feel the Squeeze 31.08.2015 Zaragozza, Spain Gasser Urs;
Swiss Soft Day 16 Poster Self-Healing Colloidal Crystals: Why Soft Particles Feel the Squeeze 04.05.2015 Paul Scherrer Institut, Villigen, Switzerland Scotti Andrea; Gasser Urs;


Self-organised

Title Date Place
Swiss Soft Day 02.03.2018 Paul Scherrer Institut, Villigen, Switzerland
Swiss Soft Day 16 04.05.2015 Paul Scherrer Institut, Villigen, Switzerland

Communication with the public

Communication Title Media Place Year
Media relations: print media, online media It takes more than peer pressure to make large microgels fit in ScienceDaily International 2016

Awards

Title Year
Young Scientist Prize of the Swiss Society for Neutron Scattering 2016, sponsored by SwissNeutronics 2016
Habilitation, University of Konstanz, Germany 2015

Associated projects

Number Title Start Funding scheme
132128 Phase behavior of concentrated microgel suspensions 01.08.2011 Project funding (Div. I-III)
132128 Phase behavior of concentrated microgel suspensions 01.08.2011 Project funding (Div. I-III)
184839 Effect of particle softness and particle charge on crystallization and glass formation in colloidal microgels 01.03.2020 Project funding (Div. I-III)

Abstract

Although the 1st order phase transition of crystal nucleation has been studied for decades, the understanding of both homogenous and heterogenous crystal nucleation are still far from being understood in detail. This is highlighted by the large differences between experimental and theoretical results for the nucleation density rate in many materials. It is generally accepted that the free energy difference between fluid and crystal, the free energy barrier for nucleation, is the key for a detailed understanding of crystal nucleation. However, the properties of small crystal nuclei forming in the supercooled fluid are not well understood and, therefore, important information about the details of the free energy barrier is missing. This is the case for both homogenous and heterogenous nucleation. While homogenous nucleation is important for the fundamental understanding of crystallization, heterogenous nucleation is of higher relevance for applications. Therefore, an improved understanding of heterogenous nucleation has the potential to lead to novel ways for the manufacturing of crystalline materials.We propose a systematic study of heterogenous crystal nucleation on curved seeds using colloidal model systems. Colloids are experimentally much more accessible than atomic or molecular materials, as their size is >10^3 times larger and the typical time scale for structural changes is >10^9 times slower. This gives the opportunity to study crystal nucleation in colloids with single particle resolution and with a time resolution allowing to follow the formation of crystal nuclei, which is hard to achieve with atomic or molecular materials. Experiments have shown that strongly curved seeds can suppress crystal nucleation, while flat seeds can give rise to spontaneous crystallization, an effect that is not captured by Classical Nucleation Theory. We plan to study crystal nucleation on seeds with controlled curvature and topology. First, convex and concave spherical seeds with positive Gaussian curvature will be studied and, secondly, toroidal seeds will be investigated that allow to study the effect of negative Gaussian curvatures and saddle points.The key parameters for crystal nucleation will be estimated using both scattering and real-space imaging techniques. This will allow a detailed characterization and comparison of heterogenous and homogenous nucleation as a function of the properties of seeds and colloidal suspensions.We plan to use hard sphere-like and soft colloidal model systems. Soft colloids (microgels) will allow to study crystal nucleation in a system being a model for materials with many potential applications. Hard spheres are an important general model system for fluids and materials with important steric interaction. Therefore, insight into the behavior of hard spheres is relevant for many materials also beyond colloids.The phase behavior of microgel suspensions is already being studied in our SNF-project 200021_132128. A one-year continuation of this project is part of this proposal, as it has an important overlap with the study of crystal nucleation in microgels.Therefore, we request funding for two PhD students:- Three years for student A working on the investigation of heterogenous crystal nucleation. He/she will work for half a year in Prof. A. Fernandez-Nieves' laboratory at GaTech, Atlanta USA, and for 2.5 years at PSI.- A one-year extension for Andrea Scotti, the PhD student of the running project 200021_132128. He will work for three months at GaTech, Atlanta USA, and for nine months at PSI. The extension is planned to overlap with the first year of student A.The extension for Andrea Scotti will allow to investigate the consequences of the responsiveness of soft microgel particles by real-space imaging and to study homogenous crystal nucleation in microgel suspensions. The latter has been found to be an interesting point during Andrea Scotti's running project, as two crystal structures appear to compete during crystal nucleation. As both students will work with microgels, project 200021_132128 and the extension for Andrea Scotti will be a platform for knowledge transfer and a quick start of student A's work on heterogenous nucleation. The students will profit from each other.
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