Towards new hard materials by structuring soft matter
Citation for published version (APA):
Florea, D., Wyss, H. M., & Meijer, H. E. H. (2009). Towards new hard materials by structuring soft matter. Poster session presented at Mate Poster Award 2009 : 14th Annual Poster Contest.
Document status and date: Published: 01/01/2009 Document Version:
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Towards new hard materials by
structuring soft matter
D. Florea1, 2, H.M. Wyss1, 2, H.E.H. Meijer1
1 Materials Technology, Eindhoven University of Technology
2 Institute for Complex Molecular Systems, Eindhoven University of Technology
/ department of mechanical engineering
Introduction
The properties of materials are often determined by their mesoscopic structuring. Phase separation processes are used already in the field of polymers to tailor the microstructure. However, in the ceramic world comparably inadequate methods (for instance blowing gas into a melt or introducing additives which are burned after mixing) are still used to produce porous materials.
Aim and Strategy
Our aim is to induce a structure in a material based on physical phenomena in colloidal systems. Colloids are particles of mesoscopic size that can assemble into a variety of structures - for instance they can form crystals, gels and glasses. With these possibilities pore size distribution and specific surface area can be tuned.
Phase separation
Inducing weak attractive
interactions between colloids
can produce a phase
separation similar to a
spinodal demixing. A weak depletion interaction can be obtained if a non adsorbing linear polymer is added to the background fluid (Fig.1). This depletion pushes the colloids together, creating an arrested
structure with well defined
features at the macroscopic level (Fig. 2).
Convection
Using the setup presented in Fig. 3 and by heating the
bottom plate an unstable
density gradient is created in
the suspension. Depending
on the conditions, different
morphologies can be obtained (Fig. 4). After creating the
patterns, different ”freeze-in”
mechanisms will be applied by
inducing strong interactions
between the particles. This will create a well defined colloidal gel network.
Fig. 1: Depletion interaction due to an unbalanced osmotic pressure
Fig. 2: Structures induced by phase separation proven by CARS microscopy images
Heated plate Cooled plate
Fig. 3: Schematic representation of Rayleigh-Bénard convection
Fig. 4: a) Hexagonal patterns b) Complex patterns
Static and dynamic information
Fig. 5: Static and dynamic light scattering setups
Structure information
Fig. 6: Olympus confocal microscope a) b)
The dream
of the materials engineer
Tailoring the microstructure of materials
without limitation by the chemical
