Πρόσκληση για την Τελετή Αποφοίτησης της 29/11/2023

21 Νοεμβρίου 2023

Παρουσίαση Μεταπτυχιακής Διπλωματικής Εργασίας της κ. Ελένης – Κωνσταντίνας Μακροπούλου

03 Νοεμβρίου 2023

ΠΑΝΕΠΙΣΤΗΜΙΟ ΚΡΗΤΗΣ

ΤΜΗΜΑ ΕΠΙΣΤΗΜΗΣ ΚΑΙ ΤΕΧΝΟΛΟΓΙΑΣ ΥΛΙΚΩΝ

ΠΑΡΟΥΣΙΑΣΗ ΜΕΤΑΠΤΥΧΙΑΚΗΣ ΔΙΠΛΩΜΑΤΙΚΗΣ ΕΡΓΑΣΙΑΣ

Τίτλος

«Electrochemically Active Supramolecular Entities in Layered Hybrid Halide Perovskites»

της Ελένης Κωνσταντίνας Μακροπούλου

μεταπτυχιακής φοιτήτριας του Τμήματος Επιστήμης και Τεχνολογίας Υλικών του Πανεπιστημίου Κρήτης

 Επιβλέπων Καθηγητής: Κωνσταντίνος Στούμπος

Τετάρτη 8 Νοεμβρίου 2023 Ώρα 10:00

H παρουσίαση θα πραγματοποιηθεί στην αίθουσα Τηλε-εκπαίδευσης (Ε130), στο κτήριο του Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών, του Πανεπιστημίου Κρήτης

Abstract

Halide perovskites are exceptional and unconventional semiconductors, known for their high optical absorption coefficients, extended charge carrier diffusion lengths, intense photoluminescence, and slow rates of non-radiative charge recombination [1]. Layered hybrid halide perovskites (AI2BIIX4 or AIIMIIX4, where A represents monovalent or bivalent cations, M represents bivalent p-block metals, and X represents halide anions), feature anionic sheets comprising corner-sharing metal-halide octahedra, selectively partitioned by organic cations, creating crystallographically ordered nanoscale sheets. This unique structure yields natural multiple quantum wells with stable excitonic features, exhibiting intense photoluminescence characteristics, even at room temperature. Intriguingly, a subset of these halide perovskites exhibits broadband optical emission, generating white light via the self-trapped exciton mechanism [2]. Understanding this fascinating trap-activated behavior necessitates careful material design, including the use of various organic spacers that can potentially induce or suppress this effect.

In this study, we have designed and synthesized a series of layered perovskites with electrochemically-active spacers, where the electrochemical state of the spacer influences the materials optical properties. The introduction of functional groups in the spacer cation adds to the structural complexity by engaging in weak supramolecular interactions, acting as perturbation probes to investigate the optical response concerning the electrochemical state of the spacer cation. Specifically, we have synthesized two sister A2PbBr4 compounds (A+ = 2,3 dihydroxy-phenylethylammonium ((HO)2-PEA) and 2-(3-aminoethyl)benzoic acid (HO2C-PEA)) as the redox-active and redox-inert pair of compounds, exhibiting a similar supramolecular interaction environment within the perovskite host. As evidenced by single-crystal X-ray diffraction experiments, the redox-active compound readily crystallizes in its partially oxidized semiquinone form during ambient environment synthesis, exhibiting similar photoluminescence characteristics to the redox-inert compound. These observations suggest formation and rapid quenching of the chemically reactive radical during the reaction. In order to probe this behavior, the reaction system was treated with a variety of chemical redox reagents targeting to obtain the compound in its fully reduced (catechol) and fully oxidized (quinone) form. Simultaneous investigations into the electrocatalytic reaction mechanism using cyclic voltammetry have indicated the presence of both the fully reduced form ((HO)2-PEA)2PbBr4 and the fully oxidized ((O=C)2-PEA)2PbBr4 in solution, prompting further optical and structural characterization of these metastable halide perovskite species.

Πρόσκληση σε Δημόσια Παρουσίαση της Διδακτορικής Διατριβής του κ. Εμμανουήλ Μαυροτσουπάκη

31 Οκτωβρίου 2023

Επιβλέπων: Παύλος Σαββίδης

(Σύμφωνα με το άρθρο 95, παρ. 3 του Ν. 4957/2022, ΦΕΚ 141 τ. Α΄/21.7.2022)

Την Δευτέρα 6 Νοεμβρίου 2023 και ώρα 12:00 στην αίθουσα Τηλεεκπαίδευσης Ε130 του Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών του Πανεπιστημίου Κρήτης, θα γίνει η δημόσια παρουσίαση και υποστήριξη της Διδακτορικής Διατριβής του υποψήφιου διδάκτορος του Τμήματος Επιστήμης και Τεχνολογίας Υλικών κ. Εμμανουήλ Μαυροτσουπάκη, με θέμα:

«Development of Perovskite Microcavities Exhibiting Strong Light Matter Coupling and Rashba-Dresselhaus Effects at Room Temperature.»

Abstract

Over the years there has been a grown interest for artificial gauge fields. A synthetic gauge field is the tailoring of specific conditions such that some quantity of neutral particles emulates the dynamics of charged particles in a magnetic field. In condensed matter physics, the spin orbit interaction, can be exploited to influence the movement of electrons through an effective magnetic field. In crystals and heterostructures lacking inversion symmetry, electrons feel the effect of effective spin orbit couplings called Dresselhaus and Rashba, usually combined together to describe their dynamics. Gauge fields due to spin-orbit coupling (SOC) play a central role in a number of exciting phenomena, accurately described topologically, where concepts such as the Berry phase and curvature enter the system Hamiltonian, taking the role of an effective magnetic field.

In this thesis, we realize an artificial gauge field for light in planar DBR microcavities containing perovskite crystals. Perovskites crystals are well known for their huge excitonic binding energy and their robust emission. They are also high anisotropic materials possessing a large linear birefringence. By harnessing these properties, and using a novel fabrication technique, we achieve the observation of strong light matter coupling between optical cavity modes and perovskite excitons at room temperature. Furthermore, the combination of TE-TM polarization splitting and the material’s anisotropy leads to the interaction between the photonic and polaritonic modes, realizing characteristic Rashba-Dresselhaus texture effects with the emergence of an effective magnetic field and nonzero Berry curvature.

These phenomena are described by a derived effective Hamiltonian for a general birefringent material inside a microcavity and can be utilized for the design of artificial gauge fields for light in polaritonic systems with the further advantage of coherent lasing emission at room temperature.

Παρουσίαση Μεταπτυχιακής Διπλωματικής Εργασίας του κ. Μίνωα Χαιρέτη

27 Οκτωβρίου 2023

ΠΑΝΕΠΙΣΤΗΜΙΟ ΚΡΗΤΗΣ

ΤΜΗΜΑ ΕΠΙΣΤΗΜΗΣ ΚΑΙ ΤΕΧΝΟΛΟΓΙΑΣ ΥΛΙΚΩΝ

ΠΑΡΟΥΣΙΑΣΗ ΜΕΤΑΠΤΥΧΙΑΚΗΣ ΔΙΠΛΩΜΑΤΙΚΗΣ ΕΡΓΑΣΙΑΣ

Τίτλος

«Fabrication and Characterization of 2D Halide Perovskite Crystals for Polaritonic Devices»  

του Μίνωα Χαιρέτη

μεταπτυχιακού φοιτητή του Τμήματος Επιστήμης και Τεχνολογίας Υλικών του Πανεπιστημίου Κρήτης

Επιβλέπων: Παύλος Σαββίδης

Τετάρτη 1 Νοεμβρίου 2023 Ώρα 10:00

H παρουσίαση θα πραγματοποιηθεί στην αίθουσα Τηλε-εκπαίδευσης (Ε130), στο κτήριο του Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών, του Πανεπιστημίου Κρήτης

Abstract

« The main aim of this work was to fabricate high quality thin 2D Halide perovskite crystals and use them to demonstrate strong light-matter coupling in various device geometries. We explored two alternative methods to fabricate crystals, namely, liquid exfoliation and solution method. We characterized the material structure using XRD as well as microscope/SEM techniques and employ optical measurements such as PL, Reflectivity, Power and Temperature dependence, to characterize exciton emission properties in this material. Liquid exfoliation method produced relatively small sized perovskite crystals not compatible with their introduction inside wavelength sized cavity. The second method, provided us with the much better results both in crystal size and structure as well as excitonic emission. Τhe successfully optimized material was then incorporated inside optical cavity and on top of a Bragg reflector. Large angle white light reflectivity measurements at room temperature revealed the appearance of resonant mode residing at the surface of the Bragg mirror whose coupling with overlaying perovskite excitons was studied.  Finally, strong-light matter coupling at room temperature was obtained when incorporating such crystals inside DBR mirror-based cavities demonstrating the great promise these materials pose for real world polaritonic applications.».

Παρουσίαση Μεταπτυχιακής Διπλωματικής Εργασίας του κ. Κοσμά Γιάνναρη (αλλαγή ώρας και αίθουσας)

20 Οκτωβρίου 2023

Τίτλος

«Development of Nanohybrid Polyurethane Coatings with Self-healing Properties»  

του Κοσμά Γιάνναρη

μεταπτυχιακού φοιτητή του Τμήματος Επιστήμης και Τεχνολογίας Υλικών του Πανεπιστημίου Κρήτης

Επιβλέπουσα: Κυριακή Χρυσοπούλου

Παρασκευή 20 Οκτωβρίου 2023, Ώρα 18:00

H παρουσίαση θα πραγματοποιηθεί στην αίθουσα Β2, στο κτήριο του Τμήματος Χημείας, του Πανεπιστημίου Κρήτης

Abstract

In recent years, self-healing materials have been a subject of increased research interest due to their ability to self-repair damages either autonomically or by external stimuli, extending their lifetime and therefore assisting in the reduction of waste. Polyurethanes represent one of the most promising materials to use towards this direction. In particular, waterborne polyurethane dispersions (WPUDs) are widely used in coatings giving the additional advantage of the reduction of volatile organic compounds (VOCs) in the environment in comparison with the traditional coatings which are solvent-based. At the same time, inorganic and / or graphitic nano-additives are widely used to improve the mechanical, thermal, optical and electronic properties of a polymeric matrix resulting in polymer nanocomposites with an overall optimized behavior.

In this work, nanohybrid polyurethane coatings were developed and their self-healing properties were evaluated. 2D materials like graphitic carbon nitride, g-C3N4, graphene oxide, GO, and Ti3C2Tx which belongs to the newly emerged class of Mxenes were dispersed in the polymeric matrix. The intrinsic self-healing mechanism of the WPUD can be improved by the presence of the inorganic compounds as they are anticipated to provide more hydrogen bonds due to the nitrogen and/or oxygen functional groups that exist on their surface or due to their ability to dissipate heat faster and thus increase the mobility of the polymer chains. Following the nano-additives synthesis, the materials were thoroughly characterized via X-ray Diffraction, XRD, Differential Scanning Calorimetry, DSC, as well as Raman and Infrared Spectroscopy, ATR-FTIR, measurements. WPUD nanocomposites were fabricated in different concentrations ranging between 0.05 - 1% wt. to investigate the effect of the additive content on the final properties. The PU/g-C3N4 nanocomposites were prepared via solid-liquid mixing while the PU/GO and PU/Ti3C2Tx via liquid-liquid mixing to avoid sedimentation problems. All nanocomposites were structurally and thermally characterized and no difference was observed in comparison to the properties of the pure PU due to the small amount of the nano-additives. Finally, coatings of all nanocomposites were fabricated by drop casting on silicon wafers. The coated surfaces were scratched creating deep and shallow cracks, using a razor blade and their self-healing efficiency was evaluated in two different temperatures (i.e., 75oC and 90oC). The healing procedure was monitored utilizing a Polarized Optical Microscope equipped with a Linkam heating stage. A quantification of the healing results was attempted by using mean grey value analysis. Similarities and differences were observed depending on the additive used; in certain cases, the self-healing ability of the pure polyurethane was found enhanced in the nanocomposites and the healing rate was found much higher, due to either better heat dissipation and / or the enhanced ability for hydrogen bond formation.

Development of the polymer nanocomposite coatings with enhanced self-healing efficiency is anticipated to enhance their usage as varnishes in wooden floors as well as paints in the car industry.

Παρουσίαση Μεταπτυχιακής Διπλωματικής Εργασίας της κ. Γιονίντας Μπούση

19 Οκτωβρίου 2023

μεταπτυχιακής φοιτήτριας του Τμήματος Επιστήμης και Τεχνολογίας Υλικών του Πανεπιστημίου Κρήτης

Τίτλος

Synthesis of Multifunctional Protein-Polymer Conjugates Using Oxygen Tolerant Approaches

Επιβλέπουσα Καθηγήτρια: Καλλιόπη Βελώνια

H παρουσίαση θα πραγματοποιηθεί την Τετάρτη 25 Οκτωβρίου 2023, Ώρα 14:00,  στην αίθουσα Β2 του Τμήματος Χημείας, του Πανεπιστημίου Κρήτης

Abstract

Protein-polymer conjugates are hybrid materials that have the potential to exhibit properties of both the biomolecule and the synthetic polymer. As such, they are expected to find application in a variety of sectors such as medicine, biotechnology, diagnostics among other.

Focus in this Thesis was the synthesis of multifunctional protein-polymer conjugates using different oxygen tolerant techniques. An oxygen-tolerant, aqueous copper-mediated polymerization approach, and an alternative, ligand-free methodology was used to synthesize protein-polymer conjugates and triblock bioconjugates in high yields. The effect of hydrophobic/hydrophilic ratio, chemical composition and temperature on the self-assembly of the biohybrid products were evaluated. Finally, a significant contribution into the development of a new, oxygen-tolerant methodology for the synthesis of protein-polymer conjugates via organocatalysis is presented in this Thesis. This greener and more sustainable approach was used to synthesize enzyme bioconjugates and evaluate their catalytic activity.

Size Exclusion Chromatography SEC), Native Polyacrylamide Gel Electrophoresis (PAGE), Nuclear Magnetic Resonance Spectroscopy (NMR), Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric analysis (TGA) and Field Emission Scanning Electron Microscopy (FE-SEM) were used characterize the products.

Παρουσίαση Διδακτορικής Διατριβής κ. Μαρίας Ψαρρού

17 Οκτωβρίου 2023

Επιβλέπουσα Καθηγήτρια: Μαρία Βαμβακάκη

(Σύμφωνα με το άρθρο 95, παρ. 3 του Ν. 4957/2022, ΦΕΚ 141 τ. Α΄/21.7.2022)

Την Τρίτη 24 Οκτωβρίου 2023 και ώρα 14:00 στην αίθουσα Τηλεκπαίδευσης Ε130 του Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών του Πανεπιστημίου Κρήτης, θα γίνει η δημόσια παρουσίαση και υποστήριξη της Διδακτορικής Διατριβής της υποψήφιας διδάκτορος του Τμήματος Επιστήμης και Τεχνολογίας Υλικών κ. Μαρίας Ψαρρού, με θέμα:

«Responsive Polymer Nanostructures and Hydrogels with Photo/Acid Sensitive Linkages for Biomedical Applications»

Περίληψη

“Stimuli–sensitive or “smart” polymers have attracted increasing interest for applications in rapidly burgeoning research fields, including biotechnology and nanomedicine, electronic devices, and others. The present PhD thesis focuses on the synthesis of novel, stimuli–degradable polymers, polymer networks and polymer–drug conjugates for potential use in drug delivery or polymer recycling.

First, we investigated thioketal and thioacetal bonds as a new family of photolabile linkages. Linear main–chain poly(thioketals) were synthesized via polycondensation and their photodegradation mechanism upon exposure to UV light was examined. The chemical and macromolecular characteristics, of the synthesized polymers were characterized by SEC and ¹H NMR spectroscopy. Next, a facile chemical platform for the synthesis of photodegradable and thermo–reversible, model thioacetal hydrogels comprising poly(ethylene glycol) (PEG) elastic chains is presented. The viscoelastic properties of the hydrogels, their photodegradation under UV exposure, and reversible formation upon heating were investigated by dynamic shear rheology. Mechanistic insights into the photodegradation mechanism of the hydrogels were gained by ¹H NMR spectroscopy kinetic studies on a model, small molecule compound.

Next, the synthesis, characterization and photochemical properties of different main–chain photodegradable poly(acylhydrazones) with photo–sensitivity ranging from the UV to the visible light range was investigated. First, a novel light– and acid–cleavable, main–chain poly(acylhydrazone) copolymer was synthesized via a step–growth reaction of a dihydrazide monomer, with a dibenzaldehyde modified poly(ethylene glycol) affording a hydrophilic alternating copolymer. The water–soluble poly(acylhydrazone) was conjugated with a hydrophobic anticancer drug, doxorubicin (DOX), affording an amphiphilic polymeric prodrug which formed spherical nanostructures in water. The synergistic effect of light–mediated degradation and acid–induced hydrolysis of the acylhydrazone bonds along the polymer chains and the release kinetics of the drug were investigated. In addition, poly(acylhydrazones) using a PEG diacylhydrazide macromonomer and judiciously selected aromatic dialdehydes or diketones as the comonomers were synthesized and the effect of the aromatic comonomers on the polymerization kinetics, self-assembly and photophysical properties was examined. Finally, the synthesis, self-assembly properties and photodegradation of alternating poly(acylhydrazone) multiblock copolymers comprising hydrophilic PEG blocks and hydrophobic PDMS blocks is presented.

In the last part of this thesis, the development of hybrid mRNA delivery systems, comprising polymer coated superparamagnetic iron oxide nanoparticles (SPIONs), is presented. The SPIONs were coated with modified natural polymers, namely oxidized dextran and quaternized chitosan. The biocompatibility of the magnetic carriers in the presence and absence of a magnetic field was tested. Owning to the presence of the cationic (quaternized chitosan) or aldehyde (oxidized dextran) groups on the particle surface, mRNA was bound via electrostatic interactions or covalent bonds, respectively, and its transfection efficiency was examined.”

Παρουσίαση Διδακτορικής Διατριβής κ. Αντωνίου Κόρδα

17 Οκτωβρίου 2023

Επιβλέπουσα: Ανθή Ρανέλλα

(Σύμφωνα με το άρθρο 95, παρ. 3 του Ν. 4957/2022, ΦΕΚ 141 τ. Α΄/21.7.2022)

Την Τρίτη 24 Οκτωβρίου 2023 και ώρα 10:30 στην αίθουσα Β2 του Τμήματος Χημείας του Πανεπιστημίου Κρήτης, θα γίνει η δημόσια παρουσίαση και υποστήριξη της Διδακτορικής Διατριβής του υποψήφιου διδάκτορος του Τμήματος Επιστήμης και Τεχνολογίας Υλικών  κ. Αντωνίου Κόρδα, με θέμα:

               «3D Scaffolds for Neural Regeneration»

Περίληψη

“Disease and trauma are primary causes of damage and malfunction of the Nervous System (NS). Tissue Engineering (TE) is a field that aims to alleviate such issues and develop strategies to repair damaged tissues. TE utilizes scaffolds that mimic the native tissue and provide substrates for cell cultures that would later be introduced to the damaged site and restore function.

To restore NS, the basic concept of TE is often combined with other strategies such as co-culture of multiple cell types and electrical stimulation (ES). The combination of scaffolds fabricated via Two-Photon Polymerization and the co-culturing of glial Schwann (SW10) and neuronal N2a cells revealed the interactions between the two cell lines in the in vitro experiments in order to develop an in vitro experimental model for PNS studies. The co-culture environment was favorable for the growth of longer neurites for extended experimental periods over the respective N2a cultures and scaffold topography affected axon directionality, highlighting the benefits of scaffolds and co-culture environments towards N2a differentiation. Furthermore, ES was applied to NE-4C stem cells cultured on flat glasses and simple groove arrays to study the different cell fates towards neurons or glial cells in CNS recovery. NE-4C cells formed neurospheres which developed tracts that were influenced by groove topography while astrocytes (glia) were also present. Additionally, the use of specific markers for both neurons and glia revealed the effect of ES on the expression of said markers, towards the understanding of NE-4C behavior and development of functional neuronal networks.”

Παρουσίαση Διδακτορικής Διατριβής κ. Χρυσάνθης-Πηνελόπης Αποστολίδου

17 Οκτωβρίου 2023

Επιβλέπουσα Καθηγήτρια: Άννα Μητράκη

(Σύμφωνα με το άρθρο 95, παρ. 3 του Ν. 4957/2022, ΦΕΚ 141 τ. Α΄/21.7.2022)

Την Δευτέρα 23 Οκτωβρίου 2023 και ώρα 12:00 στην αίθουσα Τηλεεκπαίδευσης Ε130 του Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών του Πανεπιστημίου Κρήτης, θα γίνει η δημόσια παρουσίαση και υποστήριξη της Διδακτορικής Διατριβής της υποψήφιας διδάκτορος του Τμήματος Επιστήμης και Τεχνολογίας Υλικών κ. Χρυσάνθης-Πηνελόπης Αποστολίδου, με θέμα:

«Responsive Self-Assembled Peptide Biomaterials and Applications»

«Αποκρίσιμα Αυτοοργανωμένα Πεπτιδικά Βιοϋλικά και Εφαρμογές»

Περίληψη

“Smart biomaterials" are designed to respond to external stimuli like light, pH, and metals, offering diverse applications from bioimaging to anticancer and antimicrobial applications. Peptides are highlighted as promising components for these materials due to their self-assembly properties, biocompatibility, and bio-functionality. This dissertation investigates peptides in three contexts: first, as a light-responsive delivery system encapsulating porphyrins to create antimicrobial hydrogels, analyzing structure, mechanics, and antimicrobial properties. Second, peptides are used to chelate fluorescent molecules for cancer cell bioimaging, with successful coordination and cell penetration. Finally, biocompatible peptide-metal ion nanoparticles are explored for antibacterial and anticancer purposes, revealing their potential in tumoral environments. The study overall explores smart biomaterial development, focusing on peptides and their responsiveness to external stimuli.”

PhD student position at IESL

11 Οκτωβρίου 2023

In view of the forthcoming start of the HORIZON-EIC-2023-PATHFINDEROPEN-01-01 Project Glas-A-Fuels, entitled “Single-Atom Photocatalysts Enhanced by a Self-Powered Photonic Glass Reactor to Produce Advanced Biofuels”, we are looking to recruit a PhD student for the duration of four years. The experimental work will be implemented in the ULMNP laboratory of IESL-FORTH, while the provisional starting date would be February or March 2024. The main research activities will involve the synthesis, patterning, and characterization of functional composite inorganic oxide glasses.

The applicants are kindly asked to provide their CV to Dr. I. Konidakis (ikonid@iesl.forth.gr) and Dr. E. Stratakis (stratak@iesl.forth.gr).

Requirements:

B.Sc. and M.Sc. in physical sciences (Chemistry, Physics, Materials Science).

Useful links

FORTH: https://www.forth.gr/

IESL-FORTH: http://www.iesl.forth.gr/

ULMNP: http://stratakislab.iesl.forth.gr/ and https://www.iesl.forth.gr/en/research/ULNMP-Group