Doctoral theses
Current Record: 1975 of 2491
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Identifier |
000353091 |
Title |
Εγγραφή μεσοσκοπικών δομών σε διαλύματα πολυμερών με ακτίνες LASER : συνθήκες και μηχανισμός του φαινομένου |
Alternative Title |
Writing mesoscopic structures in polymer solutions using LASER beams: Conditions and mechanism of the phenomenon |
Author
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Ανυφαντάκης, Εμμανουήλ Γ.
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Thesis advisor
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Φαράντος, Σταύρος
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Abstract |
The subject of the present thesis is the study of the unexpected response of
transparent semidilute polydiene solutions to weak visible LASER irradiation. A detailed experimental investigation was carried in order to establish a clear phenomenology of the
observed effect and try to gain insight into the underlying coupling mechanism and to establish micropatterning routes in these materials.
An imaging method based on Quantitative Phase Contrast Microscopy was established as a powerful experimental tool allowing detailed study, in particular of the
kinetics of the process.
A number of new important facts have been established:
- Surprisingly, depending on the solvent used, the polydiene solutions can respond to the optical field either by increasing or lowering the polymer concentration inside the irradiated
volume.
- The reversibility of the writing process was found to depend on the irradiation time and unexpectedly, prolonged irradiations led to long-lived structures that could not be redissolved in good solvents for the polymers. For short exposures, the LASER-induced
patterns are reversible.
- A clear analogy to non linear optical phenomena occurring in other Soft Matter systems, such as Optical Spatial Solitons and Modulation Instabilities was recognized.
- It has been shown that LASER writing can be successfully used to create impressive effects, such as the formation of very long fibrilar structures and the demonstration of Self
Induced transparency.
- Rationalizations based on expected light-matter couplings cannot account for the observed phenomenology
Though the responsible mechanism still remains unclear, the obtained knowledge concerning the various patterning possibilities offered by the different polydiene solutions
can open an avenue for much needed 3D micropatterning.
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Language |
English |
Issue date |
2010-01-18 |
Collection
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School/Department--School of Sciences and Engineering--Department of Chemistry--Doctoral theses
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Type of Work--Doctoral theses
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Permanent Link |
https://elocus.lib.uoc.gr//dlib/a/7/2/metadata-dlib-ce112253ac362492fdb2382b3eaf6bbe_1264401565.tkl
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Views |
293 |