Colloidal and micellar approaches to prepare nanostructures
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| Anzahl der Teile | 163 | |
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| Lizenz | CC-Namensnennung - keine Bearbeitung 4.0 International: Sie dürfen das Werk in unveränderter Form zu jedem legalen Zweck nutzen, vervielfältigen, verbreiten und öffentlich zugänglich machen, sofern Sie den Namen des Autors/Rechteinhabers in der von ihm festgelegten Weise nennen. | |
| Identifikatoren | 10.5446/50429 (DOI) | |
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00:00
Physikalische ChemieGangart <Erzlagerstätte>
00:09
Aktivität <Konzentration>
00:25
Golgi-ApparatLactitolNanopartikelBukett <Wein>Besprechung/Interview
00:43
VerbundwerkstoffWerkstoffkundeBiologisches MaterialNanopartikelChemische EigenschaftChemische ForschungGangart <Erzlagerstätte>WursthülleFreies ElektronBesprechung/Interview
01:49
CopolymereGangart <Erzlagerstätte>Freies ElektronFärbenPolymereHydrophobe WechselwirkungPolystyrolWursthüllef-ElementComputeranimation
02:12
EisenlegierungMicelleToluolKochsalzMetallMicelleGoldHydrophobe WechselwirkungPräkursorChemischer ReaktorEukaryontische ZelleSubstrat <Chemie>Alkoholische LösungComputeranimation
02:34
MicelleBiologisches MaterialEukaryontische ZelleFreies ElektronReglersubstanz
02:56
MetallWasserstoffMicelleChemischer ProzessSpezies <Chemie>PräkursorNanopartikelReplikationsursprungFreies ElektronCobaltoxideStickstoffatomComputeranimation
03:47
PhotochemieZellwachstumChemische ForschungMicelleWerkzeugstahlWursthülleNanopartikelGoldComputeranimation
03:55
Chemischer ProzessFunktionelle GruppeZellwachstumGangart <Erzlagerstätte>NanopartikelChemische ForschungBesprechung/Interview
04:28
Computeranimation
04:37
MetallFunktionelle GruppePolystyrolWursthüllePräkursorBukett <Wein>FettemulsionBesprechung/Interview
04:53
MetallMultiproteinkomplexEmulsionPolymereMetallFunktionelle GruppeMenschenversuchGangränPolystyrolWursthüllePräkursorChemisches ExperimentDiagramm
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Funktionelle GruppePolystyrolComputeranimation
05:15
KochsalzMetallPräkursorOrganische ChemieKomplexeCobaltoxidePlatinWursthülleSpezies <Chemie>NanopartikelElektronische ZigaretteIsotropieReglersubstanz
05:41
IsotropieWassertropfenFarbenindustrieNanopartikelReglersubstanzSol
05:55
WassertropfenBesprechung/Interview
06:08
ZähigkeitSonnenschutzmittelRauigkeitBenetzungWassertropfenWasserChemische EigenschaftComputeranimationBesprechung/Interview
06:18
OberflächenchemieWursthülleChemische StrukturKrankengeschichteBesprechung/Interview
06:44
OberflächenchemieFettsäuremethylesterWassertropfenComputeranimationBesprechung/Interview
07:08
WassertropfenFunktionelle GruppeNanopartikelHope <Diamant>
07:19
ZellwachstumFunktionelle GruppeAktivität <Konzentration>GermaneCarbonatplattformKompetenz <Bakteriologie>Besprechung/Interview
Transkript: Englisch(automatisch erzeugt)
00:10
Welcome to the Institute of Solid-State Physics at the University of Ulm. My name is Paul Simon. I would like to introduce to you some of our activities in the field of nanoscience.
00:28
So nanoscience is growing out of its infancy. Progress in preparational methods like preparing nanostructures or nanoparticles is still of utmost importance.
00:42
Let me give you an example. If you are interested in size effects, that simply means you are interested in how a material's property is depending on the size of a sample or the size of a particle. And in many cases, a measurement on one single particle is simply impossible due to the small signals.
01:06
In that case, you have to switch to a sample of particles. And in the ideal case, you need identical particles. In practice, this is impossible to get. So you have to deal with distributions of particle sizes, of inter-particle distances, of chemical compositions.
01:28
And of course, you have to prepare as narrow as possible distributions which are possible. And that's a tremendous experimental challenge. And the way we tackle that problem and the recipes we apply, that's the focus of the first part of the presentation now.
01:49
So how to prepare high quality nanoparticles? The principle we apply here is called, or we call it, the carrier principle. And I would like to explain it now, concentrating on the micellar approach here.
02:03
First step is you need a carrier. And in this case, the carriers are formed by di-block copolymers. In this case, polystyrene, poly-2-vinyl-pyridine. And if you put that into toluene, a solvent, it forms this spherical entity here called a micelle, or more in detail, an inverse micelle.
02:27
The core of this micelle can be used as a nano-reactor. You can load metal precursors like this gold salt into that core here.
02:41
And having once a solution, you carefully dip substrate into the solution and at a controlled velocity you pull it out. In this way, you get one layer of those micelles. And those micelles self-asample in a very highly hexagonal way.
03:05
You get an ordered layer. At that point, the carriers carrying the precursor of the metal have done their duty and they can be removed. And that is done by a very aggressive plasma process. You expose it to an oxygen, a hydrogen plasma, and you simply burn off the organic species.
03:27
And in parallel, you produce the metallic species. And the miracle in detail is that the metal particles, the nanoparticles, exactly are created at the position of the original micellar position.
03:46
So you get a highly ordered, as shown here, a highly ordered array of nanoparticles. In this case here with the gold salt, you get gold nanoparticles. This is a very flexible technique, allowing you to vary the particle size between, let's say, 2 and 12 nanometers
04:07
and the inter-particle distance between 30 and 120 nanometers, roughly just as a rule of thumb. And if necessary, you can in a subsequent step even further grow the particles.
04:24
We call it a seeding process. It's a photochemically induced growth which we developed together with colleagues from Dresden's Lucas Eng's group there. Let me mention, that's an important remark, all those techniques here are based on a close collaboration
04:43
between chemists and physicists, our group. In this case, Martin Muehlenau at Aachen. In the second approach, based on mini-emulsions or emulsions using colloids, polystyrene colloids, again loaded with metal precursors, it was a close collaboration with the group of the Max Planck Institute in Mainz,
05:08
Katarina Landfester's group. Again, in this case, you exploit the self-assembly of the loaded polystyrene colloid, loaded with a precursor for a metal, usually a salt or a metal complex,
05:24
and again, you remove the organic species in an isotropic oxygen plasma, and you end up here with really a beautifully hexagonally ordered array, in this case of platinum nanoparticles.
05:40
In this case, again we have control over the size, which depends on the loading of the particle and the inter-particle distance, depending on the starting size of the colloids. I just explained how to prepare nanopillars, and in one application shown here, we deposit small water droplets on top of such surfaces,
06:05
and there you can have two situations. Either the water droplet is really wetting completely, also the surfaces in between the pillars, or the water droplet is really riding on top of those pillars.
06:24
The wetting behavior is quite different. Here you can easily imagine, if you try to move the droplet, it has a tendency to get stuck, while here the riding movement is very easily done, so you have no hysteresis in that case.
06:43
What you end up here is a highly hydrophobic surface. People call it super-hydrophobic due to this nanostructuring, has to do with the lotus, the famous lotus effect in nanoscience as well, and we will show you just in a little movie,
07:03
what is the difference between this situation and this situation, if you have a droplet falling down from one centimeter and either gets stuck or it starts jumping back and forth. I hope we could demonstrate how we tackle the problem
07:21
to prepare high-quality nanoparticles, nanostructures, nanopores, nanopillars, and I also hope that it's quite clear that you need a very close collaboration between the different groups in the clean room, outside the clean room, to arrive at those results.
07:40
Of course you also need funding, and at that point I really would like to thank the German Science Foundation for supporting us in the context of our collaborative research center, SFP569, as well as the Baden-Württemberg Foundation, supporting the network of competence, functional nanostructures.
08:05
Of course, finally, I also would like to thank Ballstein for providing us this beautiful platform, allowing us to present our activities.