Study of the thermosalient effect in N’-2-Propylidene-4-hydroxybenzohydrazide and the derivatives of oxitropium bromide

disertacija

• Naslov (hrvatski): Istraživanje termoodskočnog efekta u N’-2-Propiliden-4-hidroksibenzohidrazidu i derivatima oksitropium bromida
• Autor: Teodoro Klaser
• Mentor: Željko Skoko (mentor)
• Član povjerenstva: Michele Zema https://orcid.org/0000-0001-6950-3122 (predsjednik povjerenstva)
• Član povjerenstva: Željko Skoko (član povjerenstva)
• Član povjerenstva: Mario Novak (član povjerenstva)
• Ustanova koja je dodijelila akademski / stručni stupanj: Sveučilište u Zagrebu; Prirodoslovno-matematički fakultet; (Fizički odsjek); Zagreb
• Datum i država obrane: 2021-04-26, Hrvatska
• Znanstveno / umjetničko područje, polje i grana: PRIRODNE ZNANOSTI; Fizika
• Univerzalna decimalna klasifikacija (UDC): 53 - Fizika

Sažetak

Thermosalient materials, or more colloquially called jumping crystals, are a class of materials that exhibit mechanical motion as a response to the thermal stimulus. Such materials, which are capable of extremely fast and, more important, controllable energy conversion are extremely important candidates for active actuating elements, such as flexible electronic switches, displays, artificial muscles, microfluidic valves and gates, heat sensors etc. New examples of thermosalient materials are emerging on a daily basis but yet, due to the exclusivity and individuality of the phenomenon, plus the complexity of analytical methods for its characterization, the reasons behind this colossal self-actuation remain unexplained and this thesis aims to address this lack of understanding. In this thesis two thermosalient systems, N'-2-propylidene-4-hydroxybenzohydrazide and oxitropium bromide, as well as their derivatives were extensively studied. In the case of N'-2-propylidene-4-hydroxybenzohydrazide, existence of the negative linear compressibility was experimentally proven and as well as its coupling to the negative thermal expansion. Raman measurements proved the previous theoretical suggestion of the phonon softening while approaching phase transition, and this softening helps the system transform from one thermosalient phase to another. Also, the mechanism of negative thermal expansion – the main reason for the existence of the thermosalient effect - and negative linear compressibility was fully determined. Oxitropium bromide was extensively studied in this thesis regarding its thermal behaviour prior to the polymorphic phase transition, once again proving the need of the negative thermal expansion for thermosalient properties. Two of its derivatives were prepared: scopolamine bromide hydrate and scopolamine bromide which exhibited thermosalient effect based on two novel mechanisms, previously not reported in the literature. Jumping of the crystals of scopolamine bromide hydrate is caused by the release of the water from the crystal lattice, whereas the crystals of the scopolamine bromide jump without any phase transition or chemical change and its mechanism is not yet understood.

Sažetak (engleski)

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• Ključne riječi: thermosalient effect; jumping crystals; X-ray powder diffraction; non-ambiental measurements; negative thermal expansion; negative linear compressibility; wine-rack motive; microactuators; artificial muscles; N'-2-propylidene-4-hydroxybenzohydrazide; oxitropium bromide: high-pressure X-ray diffraction; hot-stage microscopy; Raman spectroscopy; density functional theory (DFT); phase transitions
• Ključne riječi (hrvatski): termoodskočni efekt; termoodskočni kristali; skočikristali; rendgenska difrakcija; negativna linearna kompresibilnost; kristalna rešetka; N’-2-Propiliden-4-hidroksibenzohidrazid; oksitropium bromid; rendgenska difrakcija; Ramanova spektroskopija; teorija funkcionala gustoće; fazni prijelazi
• Jezik: engleski
• URN:NBN: urn:nbn:hr:217:537975
• Datum promocije: 2021
• Studijski program: Naziv: Fizika; Vrsta studija: sveučilišni; Stupanj studija: poslijediplomski doktorski; Akademski / stručni naziv: doktor/doktorica znanosti, područje prirodnih znanosti, polje fizika (dr. sc.)
• Vrsta resursa: Tekst
• Opseg: 109 str.
• Način izrade datoteke: Izvorno digitalna
• Prava pristupa: Otvoreni pristup; Datum isteka embarga: 2023-04-26
• Datum i vrijeme pohrane: 2021-06-07 08:15:16