Soft colloids represent a very active field of research since the recent progress in polymer and colloid chemistry offers wide-ranging possibilities for obtaining particles that interpolate between polymeric coils and hard spheres. In this talk we present some aspects of our recent work in this direction. We discuss the rationale for this type of research from the experimental viewpoint of structure and dynamics, and show how the combination of rheology and scattering (mainly dynamic light scattering) constitutes an indispensable tool for tuning macroscopic properties at molecular level. The following topics are addressed:
i) Colloidal star polymers: liquid-solid transitions, glass-to-crystal transition and flow control. We show that temperature variation in an intermediate solvent can play the role of volume fraction change. We achieve the glassy state, which can be also melt by inducing depletion interactions via adding smaller particles or polymers. The ultra-long time aging of star glasses may lead to crystallization.
ii) Stable block copolymer micelles with crosslinked cores: volume fraction effects and osmotic shrinking. Increasing temperature may increase the volume fraction. In a dense suspension, the neighboring micelles will exert osmotic pressure on a given particle that affects the suspension’s viscosity.
iii) Grafted clay nanoparticles: interplay of gelation and phase separation. We show how to manipute this interplay by appropriate choice of solvent, and present generic phase diagrams.
iv) Supramalecular assemblies from telechelic polymers. Depending on the type and strength of the functional end-groups, as well as the size and architecture of the polymers, different self-assembled structures could be obtained.
FORTH, Institute of Electronic Structure & Laser, and University of Crete, Dept. of Materials Science & Technology Heraklion, Crete, Greece