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Identifier

000439464

Title

Rheological signatures and origin of dynamic arrest in macromolecular systems of complex architecture

Alternative Title

Ρεολογικές υπογραφές και προέλευση δυναμικού περιορισμού σε μακρομοριακά συστήματα περίπλοκης αρχιτεκτονικής

Author

Καλαφατάκης, Νικόλαος

Thesis advisor

Βλασσόπουλος, Δημήτριος

Abstract

This work examines some salient features of star polymers in the melt state, which make them unique hybrid materials interpolating between polymers and colloids. It is already known that their rich viscoelastic response depends on the two fundamental parameters, functionality (number of arms) and arm length. Stars with low functionality and entangled arms relax stress via arm retraction. As the functionality increases, a second slower relaxation process emerges and is assigned to colloidal hopping dynamics. Here, we focus on the behavior of stars with extreme functionalities and low molar mass (mainly unentangled) arms. In such situations, the slow process is characterized by an extended low-frequency plateau modulus which reflects the caged dynamics of jammed soft solid-like self-suspended nanoparticles. Additionally, the compact structure of such highly branched macromolecular objects displays layers of distinct segmental mobilities. By employing linear rheometry, calorimetric techniques and broadband dielectric spectroscopy (in collaboration) we unravel the above intriguing properties of these materials and therefore offer new design guidelines for core-shell nanoparticles and soft composites.

Language

English

Subject

Polymeric systems

Rheology

Star- shaped polymers

Αρχιτεκτονική πολυμερών συστημάτων

Αστεροειδή πολυμερή

Ρεολογία

Issue date

2021-03-26

Collection