Paper Number
SC18 

Session
Suspensions & Colloids

Title
Telechelic Star Polymers as models for soft-patchy colloids with tunable rheology

Presentation Date and Time
October 16, 2018 (Tuesday) 11:30

Track / Room
Track 1 / Galleria I

Authors (Click on name to view author profile)

  1. Moghimi, Esmaeel (FORTH-IESL)
  2. Vlassopoulos, Dimitris (FORTH-IESL, Materials Science and Technology-University of Crete)
  3. Likos, Christos N. (Faculty of Physics, University of Vienna)
  4. Hadjichristidis, Nikos (King Abdullah University of science and Technology, KAUST, Physical Sciences and Engineering Division)

Author and Affiliation Lines (in printed abstract book)
Esmaeel Moghimi1, Dimitris Vlassopoulos2, Christos N. Likos3, and Nikos Hadjichristidis4
1FORTH-IESL, Heraklion, Greece; 2Materials Science and Technology-University of Crete, FORTH-IESL, HERAKLION, Greece; 3Faculty of Physics, University of Vienna, Vienna, Austria; 4Physical Sciences and Engineering Division, King Abdullah University of science and Technology, KAUST, Thuwal, Saudi Arabia

Speaker / Presenter 
Moghimi, Esmaeel

Text of Abstract
Telechelic Star Polymers (TSPs) are macromolecules made of f diblock copolymers grafted on a central anchoring point. Each diblock arm has a fraction of a solvophobic (at the outside) and (1-a) solvophilic monomers. The dual nature of their arms makes TSPs particularly sensitive to variations of the external conditions, such as temperature or ionic strength, which allows each particle to self-assemble into a soft particle with attractive patches on the surface. This gives rise to an unprecedented richness in the morphology of resulting material, which has been explored by computer simulations. The consequences on the dynamics have not been considered yet. Using a powerful combination of experiments and computer simulations with appropriately designed and synthetized TSPs (based of styrene-isoprene blocks with isoprene inside and different f, a and molar mass), we demonstrate that these systems are simple, robust and tunable system. They can self-assemble hierarchically into soft-patchy particles and mechanically stabilized structures. By means of rheological investigations in the linear viscoelastic regime, we determine the liquid-to-solid transition upon cooling and discuss a surprising re-entrant liquid transition with continuing cooling. We find that, in general the mechanical properties of the gel is largely depending on the temperature (i.e., interparticle attraction strength) and the cooling rate. Moreover, the imposed shear reduces the elasticity of the gel by increasing the number of intra particle bonds. Finally, we examine the direct impact of inter-particle attraction strength on the yielding behavior of TSPs during start-up shear flow experiments.