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Identifier 000402467
Title Acrylic polymers at liquid interfaces
Alternative Title Ακρυλικά πολυμερή σε υγρές επιφάνειες
Author Σεβαστάκη, Μαρία
Thesis advisor Βλασσόπουλος, Δημήτρης
Reviewer loppinet, Benoit
Πετεκίδης, Γεώργιος
Abstract In the present thesis the structural and rheological properties of viscoelastic films of acrylic polymers were studied. The experiments were performed at the air-water interface using a Langmuir trough. Our aim is to understand the relation between the macromolecular conformation and interfacial properties, and compare against respective behavior in the bulk. To this end, well-characterized samples of acrylic polymers of varying molecular weights and molecular structure were used. Langmuir monolayers were built with two different types of molecular systems, two series of homopolymers, poly (methyl methacrylate) (PMMA) and poly n(butyl acrylate) (PBA), with different molecular architectures. These two types of polymers were used because they have an affinity for air -water interface, yet they have different glass transition temperatures. The protocol involved compression-expansion cycles and rheology by means of the magnetic rod interfacial stress rheometer and step-compression measurements. We observe that upon compression, the materials (linear and more complex architectures), exhibit phase transition due to packing, which are distinct for each polymer. All acrylics exhibit reversible layers at the air-water interface, with a reproducible phase transition for all different structures and molecular weights. Flory radius analysis suggests a behavior akin to ideal conditions. Finally, the layer relaxation at different conditions (different initial concentration) is primarily independent hence the wellknown scaling in the bulk does not apply at the interface.
Language English
Subject Air-water interface
Interfacial rheology
Relaxation time
Surface pressure
Επιφάνεια αέρα- νερό
Επιφανειακή πίεση
Ρεολογία επιφανειών
Χρόνος χαλάρωσης
Issue date 2016-07-22
Collection   Faculty/Department--Faculty of Sciences and Engineering--Department of Materials Science and Technology--Post-graduate theses
  Type of Work--Post-graduate theses
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