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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, original scientific article

Abstract: 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.
Published in DKUM: 19.03.2024; Views: 83; Downloads: 8
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Poly(HIPEs) from terpenoid-derived acrylates
Stanko Kramer, Nastja Slavič, Peter Krajnc, 2023, original scientific article

Abstract: 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.
Keywords: terpenes, polyHIPE, terpenoids, bio-sourced monomers, porous polymers, high internal phase emulsions
Published in DKUM: 26.01.2024; Views: 107; Downloads: 11
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Preparation of Synthetic and Natural Porous Polymers via Multiphase Media : doctoral dissertation
Stanko Kramer, 2023, doctoral dissertation

Abstract: 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.
Keywords: HIPE, PolyHIPE, Multiple Emulsions, Functional polyHIPEs, Natural Polymers, Terpenes
Published in DKUM: 08.12.2023; Views: 240; Downloads: 51
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Light-induced palladium-catalyzed Buchwald Hartwig amination : master's thesis
Andraž Oštir, 2023, master's thesis

Abstract: The goal of this master’s thesis was to investigate the use of light to enable the acceleration of the Buchwald-Hartwig amination of deactivated aryl chlorides with an ammonium source using a newly developed and optimized state-of-the-art catalyst system. A photoreactor was designed, modelled, and constructed to allow for a reproducible reaction setup under controlled conditions. The optimal light source and reaction conditions were investigated using a model reaction. Conversion of the starting material, product yield and potential byproducts were quantified by gas chromatography (GC) analysis and confirmed by mass spectroscopy (GC/MS). The use of light (3 W 447 nm) enabled the accelerated conversion of aryl chlorides towards the amination products even at room temperature in 2 hours, which is a remarkable improvement upon the previously reported state-of-the-art. Under optimized conditions, the highest yield (88 %) was achieved using a catalyst complex formed from β-methyl naphthyl (β-MeNAP) palladium bromide and the sterically demanding ligand AdBrettPhos. The structure of the complex crystal was elucidated using X-ray crystallography after the crystallization of the catalyst species.
Keywords: Buchwald-Hartwig amination, photochemistry, palladium, room temperature, ammonium salt
Published in DKUM: 03.10.2023; Views: 531; Downloads: 50
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Razvoj sintezne metode za pripravo biarilov z Ullmannovo reakcijo : diplomsko delo univerzitetnega študijskega programa I. stopnje
Žiga Škrinjarič, 2023, undergraduate thesis

Abstract: V diplomskem delu je predstavljena sinteza in karakterizacija biarila N-benzilanilina, ki smo ga sintetizirali z Ullmannovo reakcijo po mehanizmu križnega spajanja (angl. cross coupling). Z namenom pridobitve čistega produkta s čim višjimi izkoristki smo reakcije sinteze izvedli z optimiziranjem treh reakcijskih pogojev, in sicer temperature, časa reakcije in atmosfere, v kateri je reakcija potekala. Končne produkte Ullmannove reakcije smo okarakterizirali z infrardečo in jedrsko magnetno spektroskopijo. Z infrardečo spektroskopijo smo potrdili nastanek biarila N-benzilanilina pri vseh testnih reakcijah, v nekaterih primerih tudi prisotnost benzilamina oz. jodobenzena. Z jedrsko magnetno resonanco smo potrdili njihovo kemijsko strukturo in določili njihovo razmerje v vzorcu. Ugotovili smo, da višje izkoristke N-benzilanilina dosegamo z reakcijami, ki jih izvedemo v dušikovi atmosferi pri 80°C in trajajo dlje časa, pri reakcijah na zraku pa N-benzilanilin oksidira do N- benzilidenanilina, ki se pojavlja v produktu v višjih koncentracijah.
Keywords: Ullmannova reakcija, križno spajanje, biarili, N-benzilanilin, FTIR, NMR
Published in DKUM: 11.09.2023; Views: 346; Downloads: 22
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Hiperzamreženje polihipe materialov z uporabo tiol-en klik kemije : diplomsko delo univerzitetnega študijskega programa I. stopnje
Vitan Šlamberger, 2023, undergraduate thesis

Abstract: 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.
Keywords: poliHIPE, hiperzamreženje, polimerizacija, porozni polimeri, tiol-en
Published in DKUM: 05.09.2023; Views: 270; Downloads: 62
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Sinteza in karakterizacija amino funkcionaliziranega akrilamida kot prekurzorja za inteligentne polimere : diplomsko delo univerzitetnega študijskega programa I. stopnje
Kaja Kogal, 2023, undergraduate thesis

Abstract: V tem diplomskem delu smo z nukleofilno acilno substitucijo sintetizirali funkcionalizirane akrilamide, ki so predstavljali osnovno monomerno enoto za nadaljno polimerizacijo. Reakcija sinteze monomerov je potekla med enim aminom in enim kislinskim kloridom. Za amine smo uporabljali etilen diamin (EDA), tris(2 aminoetil) amin (TAEA) ali bis(2-hidroksipropil) amin (BHPA), za kislinske kloride pa smo izbrali akriloil klorid (ACl) ali metakriloil klorid (MACl). Reaktante smo raztopili v topilu diklorometan (DCM), ob prisotnosti trietilamina (TEA). Nato smo produkte reakcij uporabili kot monomere pri prosti radikalski polimerizaciji. Polimerizacijo smo izvajali v masi ob prisotnosti termičnih iniciatorjev α,α' azobisizobutironitrila (AIBN) oziroma kalijevega peroksidisulfata (KPS). Uspešnost sinteze monomerov, torej kemijsko strukturo, smo preverili s pomočjo Fourierjeve transformacijske infrardeče spektroskopije (FTIR) in spektroskopije jedrske magnetne resonance (NMR), medtem ko smo polimere okarakterizirali s Fourierjevo transformacijsko infrardečo spektroskopijo. Produkti, ki so bili sintetizirani z metakriloil kloridom so se izkazali za uspešne pri sintezi monomerov in tudi pri polimerizaciji. Nadaljni razvoj takšnih materialov bi ogromno doprinesel na področju bioloških aplikacij, predvsem pri celičnem inženiringu in na področju odzivnih materialov.
Keywords: amino funkcionaliziran akrilamid, nukleofilna substitucija, radikalska polimerizacija, polimeri, FTIR, NMR
Published in DKUM: 04.09.2023; Views: 341; Downloads: 55
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The consolidation of emulsion templating and thiol-ene click chemistry as a route to degradable polyhipes for biomedical applications : doktorska disertacija
Viola Hobiger, 2022, doctoral dissertation

Abstract: Thiol-ene click chemistry has been on the rise for the past two decades. In the past years, it has also found its way into the synthesis of porous polymers from emulsion templating (polyHIPEs) due to its versatility and convenience. It is an especially attractive pathway for scaffolds intended for biomedical purposes since the resulting materials are often biocompatible and degradable due to hydrolyzable ester bonds introduced via the thiol monomers. The overall aim of this dissertation was to bring thiol-ene click chemistry with a focus on photopolymerization to the forefront of polyHIPE research, highlighting the great potential in combining the preparation technique of emulsion templating together with thiol-ene click chemistry. A study to understand the mechanisms of emulsion stability with a focus on already established thiol-ene formulations was conducted. It was possible to study and synthesize materials with a bicontinuous pore morphology within this project. Compared to the typical cellular pore morphology of a polyHIPE, a bicontinuous structure could be especially useful for separation applications. Furthermore, it was possible to induce a phase inversion, leading to small polymer particles. One part of the dissertation focused on synthesizing hydrophilic polyHIPEs from poly(ethylene glycol) monomers and a hydrophilic thiol through an oil-in-water high internal phase emulsion. The resulting materials exhibited high porosity and small average pore diameters of 2.2 µm. Water uptake and degradation studies were performed. The potential of the material for drug release was demonstrated with the chosen model drug salicylic acid. Furthermore, a HIPE formulation based on the acrylate 1,6-hexanediol diacrylate and thiol tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate was developed. For the developed poly(acrylate-co-thiol) polyHIPEs, the effect of oxidation thioethers present in the polymer network on the material properties was explored. This investigation was performed firstly to tune material properties, e.g. increase the glass transition temperature and tensile strength, and secondly, to highlight the oxidation properties of thioether-containing polymer networks. The oxidation responsiveness should be considered when a biomedical application is envisioned since inflammatory processes lead to oxidative stress in an organism. The formulation was also investigated for its additive manufacturing potential. The emulsion composition had to be adjusted to obtain a printable emulsion. Furthermore, it was possible to exclude harmful solvents, making the overall printing process more environmentally friendly and less hazardous for operators. A polyHIPE from the biobased vinyl ester O,O‘-(hexahydrofuro[3,2-b]furan-3,6-diyl) divinyl diadipate (GDVA), which was especially promising as a biocompatible and biodegradable scaffold for tissue engineering, was prepared together with different thiol chain-transfer agents. The synthesis of cellular interconnected polyHIPEs from these starting materials proved challenging. However, the first synthesis of a biobased vinyl ester polyHIPE could be reported. A final project was conducted in collaboration with Lithoz GmbH. In collaboration, it was possible to establish the first 3D printed ceramics from high internal phase emulsion precursors. For this purpose, trimethylolpropantriacrylte and the thiol trimethylolpropane tris(3-mercaptopropionate) were employed as monomers together with alumina particles to form a composite polyHIPE which would then be submitted to sintering, resulting in an intrinsically porous printed ceramic, allowing for high customization and complex porous morphologies.
Keywords: polyHIPE, thiol-ene, photopolymerization, additive manufacturing
Published in DKUM: 07.10.2022; Views: 570; Downloads: 97
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Imobilizacija encimov na porozni poli(glicidil metakrilat) : diplomsko delo visokošolskega strokovnega študijskega programa I. stopnje
Vesna Vrankar, 2022, undergraduate thesis

Abstract: V diplomski nalogi je prikazana študija imobilizacije encima na poliHIPE material, poli(glicidilmetakrilat-ko-etilenglikol dimetakrilat). Najprej smo pripravili poliHIPE materiale z različnimi deleži vodne faze (med 75 vol% in 90 vol%) in zamreževala (15 mol% in 30 mol%). Nato pa smo ustrezno očiščen in okarakteriziran material (FTIR spektroskopija, elementna analiza, vrstična elektronska mikroskopija in adsorpcijskaporozimetrija) uporabili kot nosilec za encim lipazo, katerega smo uporabili kot biokatalizator za hidrolizo 4-nitrofenil butirata. Za ta namen smo uporabili dve vrsti lipaze, lipazo Aspergilius niger in Candida cylindracea. Poli(glicidilmetakrilat-ko-etilenglikol dimetakrilatne) monolite smo uspešno sintetizirali s polimerizacijo emulzije z visokim deležem notranje faze tipa voda v olju. Oljna (organska, monomerna oz. zunanja) faza emulzije je vsebovala monomer glicidil metakrilat, zamreževalo etilenglikol dimateakrilat, iniciator azobisizobutironitril in surfaktant Pluronica L 121. Kot notranjo fazo smo uporabili 1,8% vodno raztopino kalcijevega klorida heksahidrata. Polimerne monolite smo okarakterizirali in funkcionalizirali. S karakterizacijo smo potrdili vključenost obeh monomerov v polimerne verige in njihovo porozno strukturo. Funkcionalizirali smo jih z nukleofilno substitucijo z encimom lipazo. Uspešnost reakcije smo preverili z elementno analizo in testno reakcijo, hidrolizo 4-nitrofenil butirata v p-nitrofenol in butirično kislino. Elementna analiza je pokazala vsebnost dušika v polimeru z vezanim (imobiliziranim) encimom, medtem ko dušika pri osnovnem polimeru elementni analizator ni zaznal. Da je bila imobilizacija encima uspešna smo potrdili tudi z reakcijo hidrolize in sicer z nastankom rumenega kompleksa p-nitrofenola, ki se pri katalizi s polimerom brez encima ni formiral.
Keywords: poliHIPE materiali, emulzije z visokim deležem notranje faze, encim, lipaza, imobilizacija, hidroliza 4-nitrofenil butirata
Published in DKUM: 23.09.2022; Views: 506; Downloads: 92
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Funkcionalizacija tiolnih skupin v poroznih politiolenih : diplomsko delo univerzitetnega študijskega programa I. stopnje
Simona Veljanovska, 2022, undergraduate thesis

Abstract: Namen te diplomske naloge je bil sintetizirati visoko porozne polimerne materiale s tiol-en klik fotopolimerizacijo, pri kateri smo kot vir tiolnih skupin uporabili pentaeritritol tetrakis (3-merkaptopropionat), kot vir vinilnih skupin pa akrilata trimetilolpropan triakrilat in 1,6-heksandiol diakrilat ter ester diviniladipat. Sintezni postopek je temeljil na fotopolimerizaciji kontinuirne faze emulzije z visokim deležem notranje faze tipa voda v olju, katere rezultat je visoko porozna morfologija materiala. Kot vir vinilnih skupin smo uporabili akrilate in ester zato, ker se med seboj razlikujejo v reaktivnosti. Ker so estri bolj reaktivni kot akrilati smo pričakovali, da v tovrstnih materialih na račun pogostejše abstrakcije vodikovega atoma iz druge molekule tiola od strani estra v propagaciji, v materialu ne bo ostalo skupin, ki jih lahko v nadaljevanju izkoristimo za različne aplikacije. Ostanejo pa v primeru akrilatov, ki pa imajo večjo težnjo po homopolimerizaciji. Mi smo sintetizirane polimere uporabili kot nosilce za bakrovo in kobaltovo sol in za oksidativno reakcijo s katero smo tiolne skupine pretvarjali v disulfidne skupine. Sintetizirani in funkcionalizirani material smo ustrezno okarakterizirali s FTIR in Ramansko spektroskopijo, elementno analizo, vrstičnim elektronskim mikroskopom, porozimetrom in Ellmanovim testom. Sinteza polimernih materialov je bila uspešna. Kot rezultat fotopolimerizacije smo dobili elastične monolitne materiale s tipično poliHIPE morfologijo v primeru uporabljenih akrilatov in bikontinuirno morfologijo v primeru estra. Polimera z akriltanim monomerom sta vsebovala večji delež prostih tiolnih skupin kakor material z estrskim monomerom. Reakcija z jodom v acetonitrilu, ki pretvarja tiolne skupine v disulfidne, je bila z Ramansko spektroskopijo uspešno potrjena le za akrilatna monomera.
Keywords: poliHIPE, emulzija z visokim deležem notranje faze, tiol-en klik reakcija, fotopolimerizacija, oksidativna reakcija
Published in DKUM: 22.09.2022; Views: 437; Downloads: 37
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