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1.
Terpenes as natural building blocks for the synthesis of hierarchically porous polymers : bio-based polyHIPEs with high surface areas
Stanko Kramer, Nika Skušek, Peter Krajnc, 2023, izvirni znanstveni članek

Opis: PolyHIPEs are hierarchically porous polymers which are generally synthesised from synthetic constituents produced from fossil fuels. The need to produce sustainable materials makes terpenes great candidates for the preparation of polyHIPEs as they possess polymerisable functionalities, while being abundant in various plants and flowers. In this study limonene, carvone and myrcene are used to produce bio-based polyHIPEs by utilising multifunctional acrylates (trimethylol propane triacrylate (TMPTA) and pentaerythritol tetraacrylate (PETA)) as the comonomers in the polymerisation process. By using the two monomer units it was possible to synthesise poly(limonene-co-TMPTA), poly(limonene-co-PETA), poly(carvone-coTMPTA), poly(carvone-co-PETA), poly(myrcene-co-TMPTA) and poly(myrcene-co-PETA) HIPEs. The terpene and acrylate ratios are varied to study the incorporation of the terpenes into the polyHIPE and the effects on the morphological properties. While the synthesis of terpene-based polyHIPEs was successful, the degree of limonene and carvone incorporation reduces when the content thereof in the HIPE mixture is increased. The synthesised polyHIPEs had a pore diameter ranging from 5.51 to 11.63 μm, while the specific surface area ranged from 2.7 m2 g−1 and up to approximately 300 m2 g−1. This study is the first study that demonstrates the possibility of preparing polyHIPEs from limonene and carvone. Additionally, it shows that it is possible to synthesise porous polymers from sustainable constituents.
Objavljeno v DKUM: 19.03.2024; Ogledov: 83; Prenosov: 8
.pdf Celotno besedilo (3,88 MB)
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2.
Poly(HIPEs) from terpenoid-derived acrylates
Stanko Kramer, Nastja Slavič, Peter Krajnc, 2023, izvirni znanstveni članek

Opis: The need for utilization of non-fossil fuel derived sources for polymer production is growing. In this study the terpenoids tetrahydrogeraniol, citronellol and nopol were modified with an esterification procedure using acryloyl chloride, forming terpenoid acrylates. The synthesised acrylates were used for the production of hierarchically porous polymers via high internal phase emulsion (HIPE) templating with emulsions consisting of an organic (monomer) phase and an aqueous phase with a volume fraction of 85%. The acrylate terpenoids in the organic phase were crosslinked with trimethylolpropane triacrylate (TMPTA) to form the polyHIPEs. A crosslinking degree of 5 and 10 mol% was used to investigate the feasibility of polyHIPE production. While both crosslinking degrees enabled the synthesis of polymers, only the 10 mol% crosslinking yielded the typical interconnected porous cellular topology. The average primary pore diameter in the case of the tetrahydrogeraniol acrylate and citronellyl acrylate was 15.6 and 16.5 μm, respectively, while the average primary pore diameter in the case of nopol acrylate was 5.6 μm.
Ključne besede: terpenes, polyHIPE, terpenoids, bio-sourced monomers, porous polymers, high internal phase emulsions
Objavljeno v DKUM: 26.01.2024; Ogledov: 107; Prenosov: 11
.pdf Celotno besedilo (1,75 MB)

3.
Preparation of Synthetic and Natural Porous Polymers via Multiphase Media : doctoral dissertation
Stanko Kramer, 2023, doktorska disertacija

Opis: PolyHIPEs are highly porous polymers with an interconnecting porous structure. They have found usage in the removal of pollutants, water clean-up, oil spill removal, catalysis, controlled release of active compounds, wound dressing and tissue engineering. The wide applicability of polyHIPEs is possible through their inherent porosity and chemical diversity. The aim of this dissertation was to increase the chemical diversity of polyHIPEs, develop an efficient method for the synthesis of polyHIPE beads and to use natural resources for the synthesis of polyHIPEs, subsequently, paving the pathway to more sustainable synthetic procedures. PolyHIPEs tend to have poor mechanical properties, therefore, it was crucial to investigate the influence of the internal phase volume, initation type (photo vs thermal) and monomer functionality on the mechanical and morphological properties of thiol-ene polyHIPEs. The results show that the main factors influencing the morphological and mechanical properties are the monomer structure and the internal phase volume. Besides the inherent porosity and chemical versatility typical of polyHIPEs, they can also be produced in various shapes, e.g., monoliths, membranes and beads. Therefore, the dissertation also focuses on the synthesis of polyHIPE beads. The polyHIPE beads were produced through the usage of water-in-oil-in-water (W/O/W) multiple emulsions. To enable the synthesise of open porous polyHIPE beads, thiol-ene polymerisation was combined with photopolymerisation to guarantee a rapid polymerisation prior the break-down of the multiple emulsion. Consequently, it was possible to synthesise polyHIPE beads. The first study showed that by altering the thiol to acrylate ratio in favour of the acrylate the degradation rate of the synthesised polyHIPE beads gets reduced. Additionally, it was demonstrated that the beads can be readily functionalised with allyl amine and used for the adsorption of methylene blue (12.0 mg/g in 24 hours). The next study combined polyHIPE beads with magnetic nanoparticles (MNPs) to produce magnetic polyHIPE beads which were used for the removal of Pb2+. To produce the magnetic polyHIPE beads, magnetic nanoparticles (MNPs) were added to the organic phase. The MNPs get incorporated into the polymer-network after the polymerisation, therefore, forming magnetic polyHIPE beads. The MNPs were shown to influence the morphology and the size of the beads. Additionally, the polyHIPE beads were shown to remove up to 97.0 % of Pb2+ after 24 hours from a 2.9 mg/L solution of Pb2+. In the last study related to the synthesis of polyHIPE beads, functional polyHIPE beads were produced and then functionalised to enable the binding of the enzyme invertase. These beads were then utilised for the hydrolysis of sucrose. The conversion of sucrose to glucose and fructose was 100% after 60 minutes for the polyHIPE beads, while the conversion for non-porous beads was only 6.5%. The last part of the thesis focused on more sustainable/natural approaches to polyHIPE synthesis. The first study utilised limonene as a replacement to conventional solvents (e.g., cyclohexane) in the production of O/W HIPEs and the polymerisation thereof into polyHIPEs. It was shown that limonene can be used as an efficient replacement in the production of polyHIPEs. The next study used natural resources (terpenoids) which were modified to contain polymerisable units, which were used for the synthesis of terpenoid-based polyHIPEs. The synthesised monomers were then crosslinked with 5 and 10 mol. % TMPTA to form polyHIPEs, consequently producing porous polymers. The last study in this thesis used the terpenes limonene, carvone and myrcene to produce bio-based polyHIPEs by utilising multifunctional acrylates (PETA and TMPTA) as the comonomers. This study demonstrates that it is possible to prepare polyHIPEs from commercially available terpenes, therefore, moving the field of polyHIPEs into a more sustainable direction.
Ključne besede: HIPE, PolyHIPE, Multiple Emulsions, Functional polyHIPEs, Natural Polymers, Terpenes
Objavljeno v DKUM: 08.12.2023; Ogledov: 240; Prenosov: 51
.pdf Celotno besedilo (8,08 MB)

4.
Hiperzamreženje polihipe materialov z uporabo tiol-en klik kemije : diplomsko delo univerzitetnega študijskega programa I. stopnje
Vitan Šlamberger, 2023, diplomsko delo

Opis: V diplomskem delu je predstavljena priprava poroznih polimerov na osnovi 2-etilheksil akrilata (EHA) in različnih zamreževal (divinil adipat (DVA), etilen glikol dimetakrilat (EGDMA), 1,4 – butandiol divinil eter (BDVE)) z uporabo polimerizacije v emulziji z visokim deležem notranje faze oz. HIP emulziji. Kopolimere smo pripravili v različnih razmerjih EHA in zamreževala, pri čemer smo dodali še surfaktant PEL 121 in iniciator AIBN. Poleg prej naštetih komponent, ki sestavljajo kontinuirno fazo, smo dodali še 80 vol.% vodne faze, ki je bila 1,78-% vodna raztopina CaCl2. Sintetizirane polimere smo hiperzamrežili z uporabo radikalskega hiperzamreženja in tiol-en hiperzarmeženja z di- in tri-tiolom z namenom povišanja specifične površine. Pri treh od devetih sintetiziranih polimerih smo opazili poliHIPE strukture z uporabo vrstične elektronske mikroskopije, pri ostalih pa smo opazili bikontinuirno morfologijo. Specifične površine polimerov so bile izmerjene z uporabo porozimetrije na podlagi modela BET, in sicer do 9,02 m2/g, kar je predstavljalo približno 1,5-kratno povišanje specifične površine zaradi hiperzamreženja z di-tiolom.
Ključne besede: poliHIPE, hiperzamreženje, polimerizacija, porozni polimeri, tiol-en
Objavljeno v DKUM: 05.09.2023; Ogledov: 270; Prenosov: 62
.pdf Celotno besedilo (3,62 MB)

5.
Polimerne strukture s spremenljivo porazdelitvijo por : diplomsko delo univerzitetnega študijskega programa I. stopnje
Nika Marija Murenc, 2022, diplomsko delo

Opis: V diplomski nalogi smo želeli pripraviti material s stopenjsko velikostjo por, zato smo si najprej pripravili vzorce, kjer smo kot monomer uporabili trimetilolpropan triakrilat(TMPTA), mu dodali toluen, surfaktant Hypermer B246 (HB246) in fotoiniciator Irgacure 819 (I819). Tej organski fazi smo med mešanjem po kapljicah dodali 80 vol. % vodne faze. Ker nas je zanimala sprememba v velikosti por, smo pripravili vzorce, pri katerih smo dodajali različne deleže topila DMSO in THF (od 1% do 32%). Poleg dodajanja različnih deležev topil, pa smo pripravili tudi vzorce, ki smo jih mešali pri različnih hitrostih. Določili smo velikosti por, ki so se nahajale v območju do 60 µm, ter opazovali porazdelitve v tem območju glede na posamezni vzorec. Z elementno analizo smo dokazali, da se sestava pri posameznih vzorcih ni spremenila. S pomočjo navedenih določitev smo pripravili tri vzorce, ki so imeli dovolj veliko razliko v velikosti por, in s kombiniranjem teh pripravili materiale s stopenjsko poroznostjo. Zaradi dovolj velike viskoznosti HIP emulzij, smo vzorce preprosto prelili enega na drugega, ne da bi pri tem prišlo do mešanja emulzij, kar je omogočilo pripravo vzorcev s spremenljivo porazdelitvijo por.
Ključne besede: HIP emulzije, poliHIPE materiali, poroznost, porozni materiali, gradientni materiali, porozni gradientni materiali
Objavljeno v DKUM: 15.09.2022; Ogledov: 411; Prenosov: 29
.pdf Celotno besedilo (3,16 MB)

6.
Terpeni iz bioloških virov za pripravo makromolekul : diplomsko delo visokošolskega strokovnega študijskega programa I. stopnje
Irena Ačko, 2022, diplomsko delo

Opis: Terpeni so spojine naravnega izvora in zaradi tega predstavljajo dobro alternativo spojinam sintetičnega izvora, predvsem tistim, ki so petrokemičnega izvora. Zaradi strukturne raznolikosti terpenov in različne reaktivnosti je njihov spekter uporabe širok. V diplomskem delu je predstavljena priprava poroznih polimernih materialov iz različnih akrilatov – trimetilolpropan triakrilat in pentaeritritol tetraakrilat ter terpenov – karvon in mircen. Delež notranje faze je bil 80 vol. %. Za pripravo smo uporabili karvon in trimetilolpropan triakrilat ter mircen in pentaeritritol tetraakrilat v razmerjih 1:3, 1:1, in 3:1. Namen priprave poroznih materialov z različnimi razmerji akrilata in terpena je ugotavljanje vpliva različnih terpenov in deležev le-teh na vrednosti specifične površine in velikosti por. Na pripravljenem materialu smo izvedli analizo morfologije z vrstičnim elektronskim mikroskopom. Opazovali smo primarne in sekundarne pore. Po izračunu povprečja primarnih in sekundarnih por smo ugotovili, da so vrednosti relativno podobne, kar nakazuje na to, da razmerje terpen:akrilat ter sestava materiala nimata signifikantnega vpliva na velikost por. Povprečni premeri primarnih por se gibajo med 6 μm in 10 μm, povprečni premeri sekundarnih por pa imajo vrednosti okoli 1 μm. Z Brunauer-Emmett-Teller analizo smo izmerili specifične površine in na podlagi dobljenih vrednosti ugotovili, da višji kot je delež akrilata, višja bo stopnja zamreženosti, kar se bo posledično odrazilo v visokih vrednostih specifične površine in obratno, višji bo delež terpena, nižja bo specifična površina. Iz rezultatov o specifični površini in premerov por smo ugotovili tudi, da manjši kot so premeri por, večja je specifična površina. Z elementno analizo smo določili vsebnost ogljika in vodika v vzorcih s karvonom in trimetilolpropan triakrilatom. Rezultate elementne analize smo uporabili za izračun vključenosti karvona in ugotovili, da je med 4 mol. % in 37 mol. %.
Ključne besede: poliHIPE, terpeni, karvon, mircen, porozni materiali
Objavljeno v DKUM: 13.09.2022; Ogledov: 470; Prenosov: 24
.pdf Celotno besedilo (2,68 MB)

7.
Priprava funkcionalnih monomerov iz acikličnih terpenov : diplomsko delo univerzitetnega študijskega programa I. stopnje
Nastja Slavič, 2022, diplomsko delo

Opis: Naraščajoče onesnaževanje okolja in izčrpavanje fosilnih virov je v zadnjih letih sprožilo vse več zanimanja za biološko pridobljene monomere na osnovi terpena. Ti so zaradi svoje strukturne raznolikosti vsestranski za uporabo v različnih aplikacijah na številnih področjih. V okviru tega diplomskega dela smo najprej sintetizirali monomere z zaestrenjem izbranega terpenskega alkohola z akriloil kloridom. Izbrali smo tetrahidrogeraniol, citronelol in (1R)-(−)-nopol. Prisotnost hidroksilne skupine na izbranem terpenolu smo uporabili za vključitev akrilatne skupine. Uporabili smo dve topili, in sicer trietilamin za akriloil klorid in diklorometan za izbran terpen. V nadaljevanju nas je zanimalo ali pripravljeni monomeri polimerizirajo, zato smo s polimerizacijo v masi pripravili polimere zamrežene s trimetilolpropan triakrilatom (TMPTA) in etilenglikol dimetakrilatom (EGDMA), kot iniciator pa smo izbrali α,α'-azoisobutironitril (AIBN). S Fourierovo transformacijsko infrardečo spektroskopijo (FTIR) smo preučili kemijsko sestavo sintetiziranih monomerov in polimerov. Uspešnost sinteze monomerov smo preverili s spektroskopijo jedrske magnetne resonance (NMR), z elementno analizo pa smo preučili sestavo polimernega vzorca. Sintetizirani akrilati iz zgoraj omenjenih terpenov bi lahko v prihodnosti predstavljali dobro alternativo nekaterim komercialno dostopnim spojinam na osnovi etilheksila, izoamila in norbornena, ki se trenutno v veliki meri uporabljajo v industriji za vse vrste aplikacij.
Ključne besede: terpeni, terpenoli, naravni monomeri, esterifikacija, polimerizacija
Objavljeno v DKUM: 31.08.2022; Ogledov: 541; Prenosov: 96
.pdf Celotno besedilo (1,85 MB)

8.
Polimerizacija terpenov v koloidnih prekurzorjih : diplomsko delo univerzitetnega študijskega programa I. stopnje
Nika Skušek, 2022, diplomsko delo

Opis: Naravni polimeri v vse večji meri nadomeščajo sintetične ekvivalente iz fosilnih goriv. Za njihovo sintezo se med drugim uporabljajo terpeni, ki so široko dostopni kot stranski produkti pri predelavi citrusov. Polimeri sintetizirani iz le-teh imajo nizko toksičnost in so potencialno biorazgradljivi, zato se intenzivno raziskujejo kot prekurzorji za razvoj trajnostnih polimerov. V diplomskem delu smo z uporabo emulzij z visokim deležem notranje faze, t.i. HIPE, sintetizirali porozne poliHIPE materiale na osnovi izbranih terpenov, tj. limonena in mircena. Pripravili smo kopolimere različnih razmerij terpena proti akrilatu (1:1, 1:3 in 3:1), pri čemer smo kot drugi monomer v organski fazi uporabili trimetilolpropan triakrilat (TMPTA) ob dodatku surfaktanta Hypermer B246, iniciatorja AIBN in toluena. Poleg tega smo glede na celotni volumen emulzije dodali 80 vol.% vodne faze. Na podlagi različnih razmerij smo ugotavljali vključenost terpena v polimeru in opazovali vpliv na morfologijo ter poroznost. Vzorce smo očistili v Soxhletovem aparatu in karakterizirali z različnimi metodami. Kemijsko sestavo smo preverili z elementno analizo, iz dobljenih vrednosti smo izračunali vključenost terpena v našem vzorcu. Z elektronsko vrstično mikroskopijo (SEM) smo preverili ali imajo vzorci ustrezno, za poliHIPE značilno, porozno strukturo sestavljeno iz primarnih in sekundarnih por, ki smo jih tudi izmerili. Po metodi BET smo izmerili specifične površine, določili smo še celokupno in skeletno gostoto iz katere smo izračunali poroznost. Nenazadnje pa smo posneli FTIR spektre s katerimi smo se prepričali o uspešnosti sinteze.
Ključne besede: poliHIPE, terpeni, naravni polimeri, HIPE, kopolimeri
Objavljeno v DKUM: 31.08.2022; Ogledov: 542; Prenosov: 106
.pdf Celotno besedilo (6,72 MB)

9.
Priprava poroznih polimerov na osnovi celuloze z uporabo emulzij z visokim deležem notranje faze : bachelor thesis
Paula Estévez Recio, 2021, diplomsko delo

Opis: Namen tega dela je razložiti sintezo poliHIPE, ki vsebujejo celulozo. PoliHIPE so bili pripravljeni z uporabo emulzij olja v vodi (O/W). Vodna (kontinuirana) faza je bila sestavljena iz akrilne kisline (AA), karboksimetilceluloze (CMC), N,N′-metilenbisakrilamida (MBA), površinsko aktivne snovi in ustreznih iniciatorjev, medtem ko je bila oljna (notranja) faza toluen. Polimerizacija je potekala termično pri 60 ºC 24 ur. Dobljeni polimeri so imeli diskontinuitetno morfologijo poliHIPE z različnimi premeri, odvisno od stopnje zamreženja in količine CMC. Zanimivo je, da sta prisotnost CMC in višja stopnja zamreženja (30 %) povzročila nastanek večjih por, ki so v bistvu oblikovale material s tremi stopnjami poroznosti - primarno, sekundarno in terciarno. Velikost por je bila od približno 32 μm (0 % CMC) do 260 μm (1 % CMC), površina BET pa se je gibala od približno 1,3 m2/g do 3,9 m2/g. PoliHIPE smo uporabili tudi za adsorpcijo metilen modrega (MB). Pokazalo se je, da prisotnost CMC poveča adsorpcijo MB, vendar se pri višjih koncentracijah CMC adsorpcija zmanjša, kar kaže, da je idealna količina CMC pod 2,5 % (raztopina CMC).
Ključne besede: PolyHIPE, akrilna kislina, celuloza, adsorpcija, poroznost
Objavljeno v DKUM: 22.09.2021; Ogledov: 888; Prenosov: 55
.pdf Celotno besedilo (10,55 MB)

10.
Porous beads from multiple emulsions with thiol-ene polymerisation : magistrsko delo
Stanko Kramer, 2019, magistrsko delo

Opis: This thesis aims to explain the process of porous bead synthesis. The porous beads were prepared from a multiple emulsion water-in-oil-in-water (W/OW) system. The W/O/W multiple emulsion was made up of a High Internal Phase Emulsion (HIPE (primary emulsion)) and a suspension phase. The HIPE consisted of pentaerythritol tetrakis (3 mercaptopropionate) (TT) in combination with either divinyl adipate (DVA) or trimethylolpropane triacrylate (TMPTA) and an internal phase volume fraction of 80 %. The suspension phase consisted of an aqueous phase with dissolved surfactants which stabilised the secondary emulsion. The surfactants which stabilised the secondary emulsion were polyvinylpyrrolidone K30 (PVP K30) and polyvinylpyrrolidone K90 (PVP K90). The polymerisation was carried out thermally at first for 24 hours and later under UV light and daylight, as the thermally initiated polymerisation was unsuccessful due to coalesence. The beads that were obtained using the photoinitiated polymerisation were porous with a mostly bicontinuous structure and varying diameters. The viscosity of the primary emulsion (HIPE) had the greatest influence on the stability of the entire W/O/W emulsion. By adding more than 5 wt. % of toluene to the primary emulsion, the emulsion broke down and did not successfully polymerise. Another important factor was the ratio of the functional groups in the case of TT-co-TMPTA, which greatly affected the yield and structure of the obtained beads. The diameters of the spherical particles were dependent on the viscosity, monomer ratio and surfactant used in the suspension phase. The inner structure of the beads was mostly bicontinuous with occasional pores that resembled a polyHIPE structure. The obtained beads had a yield of up to 80 % in the case of TT-co-DVA and a yield of up to 90 % in the case of TMPTA-co-DVA
Ključne besede: polyHIPE, thiol-ene, suspension polymerisation, porous beads, HIPE
Objavljeno v DKUM: 17.09.2019; Ogledov: 1421; Prenosov: 216
.pdf Celotno besedilo (3,56 MB)

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