E-Locus - Institutional Repository of the University of Crete

Home Collections Type of Work Post-graduate theses

Post-graduate theses

Current Record: 5444 of 6553

[Add to Basket]

Identifier

000421563

Title

Σύνθεση και χαρακτηρισμός Πολυεδρικών Ολιγομερικών Σιλοξανίων (POSS) και φωσφονικών παραγώγων τους και ο ρόλος τους ως στερεωτικά για την προστασία της Πολιτιστικής Κληρονομιάς

Alternative Title

Synthesis and characterization of Polyhedral Oligomeric Silsesquioxanes (POSS) and their phosphonate derivatives: application as consolidants for the protection of Cultural Heritage

Author

Λιακάκη-Σταυροπούλου, Στεφανία

Thesis advisor

Δημάδης, Κωνσταντίνος

Reviewer

Σπύρος, Απόστολος
Μήλιος, Κωνσταντίνος

Abstract

Silsesquioxanes are inorganic-organic hybrid materials of the general formula RnSinO3n/2, where R can be hydrogen or a wide range of alkyl, alkenyl, aryl or siloxy groups. Silsesquioxanes can form random structures, ladder polymers, cage-like structures and incomplete condensed polyhedral species. The architecture of Polyhedral Oligomeric Silsesquioxanes (POSS) is cage-like where n is greater than or equal to 4. POSS are unique molecules consisting of rigid silica cores with eight organic functional groups anchored to the vertices of the silica core, 1-3 nm in diameter. Phosphonic acids are organic molecules that possess one or more functional phosphonate –PO₃H₂ groups connected to an organic fragment through stable, covalent P-C bonds. In the present Thesis, the first step was the synthesis and characterization of octakis(3-chloroammoniumpropyl)octasilsesquioxane, with cage-like structure consisting of 8 Si atoms and a primary amine R group (CH₂CH₂CH₂NH₃⁺Cl^-). The second step was the synthesis of a new aminophosphonate derivative of POSS with 16 phosphonate groups (P-POSS) via the Mannich type reaction. The new P-POSS ligand was used in synthetic reactions with divalent metal ions Μ²⁺ (Μ = Ca, Sr, Ba), in order to obtain new metal phosphonate coordination polymers. The products were characterized by ¹Η NMR, ¹³C NMR, ²⁹Si NMR, ³¹P NMR, FT-IR and EDS measurements. Lastly, the consolidation efficiency of P-POSS and metal derivatives were evaluated on gypsum stones aiming at preserving the gypsum structural elements of the Knossos palace.

Language

Greek

Subject

Mannich type reaction

Phosphonic acids

Αντίδραση Mannich

Μεταλλοφωσφονικές ενώσεις

Πολυεδρικά σιλοξάνια

Στερεωτικά υλικά

Φωσφονικά οξέα

Issue date

2019-03-27