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Identifier |
000383744 |
Title |
Dynamics and kinetics in soft matter systems : effect of light and shear in concentrated polydiene solutions and colloidal suspensions |
Alternative Title |
Δυναμική και κινητική σε συστήματα χαλαρής ύλης : |
Author
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Παμβούξογλου, Ανδρέας
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Thesis advisor
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George, Fytas
George, Petekidis
Benoit, Loppinet
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Reviewer
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Dimitris, Vlassopoulos
Stergios, Pispas
Ulrich Jonas
Apostolos, Rizos
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Abstract |
This thesis is concerned with the study of two projects related with mechanical and
optical forces in soft matter systems. In the first part, the effect of light irradiation in
polydiene solutions was examined. Specifically the characterization of the light‐induced
fibers and the effect of light in more complicated polydiene‐based systems were studied.
We show that upon irradiation radicals are formed, which crosslink the material, creating
fibers. We also revealed that by changing the sample’s parameter (temperature, solvent and
microstructure) we affect the kinetics of pattern formation. More specifically multiblock
(diblock, triblock) copolymers in selective solvents, open new routes to patterning due to
rich phase diagram.
In the second part, we report on the structure and dynamics in suspensions of soft
colloidal core‐shell particles up to the glass regime. Particles with different chain molecular
weight grafted on a hard core were used to investigate the effect of softness. In the liquid
regime due to the high refractive index mismatch between particle‐solvent, we used 3D
Dynamic Light Scattering. We demonstrate that the dynamics of the system can be
interpreted with permeable spherical particles model, varying only one parameter, the
hydrodynamic penetration depth x. In the glass regime the system is strongly non‐ergodic
and ages with time. Using Multispeckle Dynamic Light scattering (MSDLS) we found a glasscrystal
re‐entrant transition, independent of particle’s softness. The effect of softness upon
shear was also investigated through rheology. A series of linear (dynamic frequency sweep),
nonlinear (dynamic strain sweep, LAOS, flow curves) and transient (start‐up) experiments
were performed, demonstrating clearly the effect of softness.
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Language |
English |
Issue date |
2014-03-28 |
Collection
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School/Department--School of Sciences and Engineering--Department of Materials Science and Technology--Doctoral theses
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Type of Work--Doctoral theses
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Permanent Link |
https://elocus.lib.uoc.gr//dlib/a/6/d/metadata-dlib-1399022117-169582-12259.tkl
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Views |
446 |