Paper Number
SC25 

Session
Suspensions & Colloids

Title
Short and soft nanocylinders: Multi-domain structure and tunable rheology

Presentation Date and Time
October 16, 2018 (Tuesday) 4:35

Track / Room
Track 1 / Galleria I

Authors (Click on name to view author profile)

1. Parisi, Daniele (FORTH-IESL, Materials Science and Technology-University of Crete)
2. Ruan, Ying-Bo (Chinese Academy of Sciences, Institute of Chemistry)
3. Liu, Chen-Yang (Chinese Academy of Sciences, Institute of Chemistry)
4. Loppinet, Benoit (FORTH-IESL, Insitute of Electronic Structure and Laser)
5. Vlassopoulos, Dimitris (FORTH-IESL, Materials Science and Technology-University of Crete)

Author and Affiliation Lines (in printed abstract book)
Daniele Parisi¹, Ying-Bo Ruan², Chen-Yang Liu², Benoit Loppinet³, and Dimitris Vlassopoulos^1
1Materials Science and Technology-University of Crete, FORTH-IESL, HERAKLION, Greece; ²Institute of Chemistry, Chinese Academy of Sciences, Beijing, China; ³Insitute of Electronic Structure and Laser, FORTH-IESL, HERAKLION, Greece

Speaker / Presenter 
Parisi, Daniele

Text of Abstract
Whereas static and dynamic properties of cylinders with large aspect ratio (L/D>10) have been extensively investigated, much less is known for short cylinders (L/D<10). Only recently, simulations and experiments have shown complexities associated with the isotropic-to-liquid crystalline phase transition in short cylinders, where particles kinetically arrested into macroscopic multi-domain structures before eventually arranging into a smectic phase. Additionally, the role of softness on structure and dynamics, well established for spherical colloids, is unexplored for short nanocylinders. In this experimental work we introduce a new model system of short and soft (grafted) cylinders (L/D=6) in order to link structure, softness and dynamics by combining SAXS, DLS, visual observations and different rheological techniques: piezo rheometry for high frequencies (>100rad/s), standard frequency sweeps (0.01 to 100 rad/s) and creep to extend the low frequency region. We find an unprecedentedly rich rheological response embracing a broad range of concentrations, from dilute to nearly melt state. An isotropic liquid gives rise to an isotropic multi-scale structure with local orientation, to an arrested state and finally to a hexagonally packed arrangement. These states exhibit distinct rheological signatures, encompassing polymer layer and colloidal responses, which we discussed in detail, in the linear and nonlinear regime. We argue that this class of nanocolloids with softness and short-ranged orientational order offer new possibilities for tailoring flow properties of suspensions.