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1.
Porozni organogeli: sinteza in absorpcija
Stanko Kramer, 2017, undergraduate thesis

Abstract: Geli so v kapljevino namočena mreža polimernih molekul, t.i. gelska mreža, katere agregatno stanje lahko uvrstimo med trdno in kapljevinasto, kar pomeni, da so poltrdi sistem. Glede na topilo jih delimo na organogele (absorbirajo nepolarna (organska) topila) in hidrogele (absorbirajo vodo). Organogeli predstavljajo obetajoče absorpcijske materiale za čiščenje oljnih razlitij, saj imajo visoko specifično površino pod pogoji nabrekanja in so sposobni vpiti večje količine apolarnih tekočin. V diplomskem delu smo pripravili organogele na osnovi norbornena in njegovih derivatov. Z uporabo emulzij z visokim deležem notranje faze smo pripravili visoko porozne t.i. poliHIPE organogele. S polimerizacijo v raztopini smo pripravili neporozne t.i. bulk organogele. Sintezo smo izvedli z uporabo metatezne polimerizacije z odpiranjem obroča (ang. Ring Opening Metathesis Polymerisation, ROMP). Nastale organogele iz diciklopentadiena (DCPD), 2-norbornena (NOR) in ciklooktadiena (COD) smo ustrezno karakterizirali, nato smo izvedli test absorpcije organskih topil in dveh različnih naftnih derivatov. Preučili smo kako na absorpcijo vplivajo struktura organogela (porozen oz. neporozen) in stopnja zamreženja polimernega ogrodja. Porozno morfologijo skeleta smo preučili z elektronsko vrstično mikroskopijo (SEM), medtem ko smo test absorpcije izvedli gravimetrično. S SEM analizo smo dokazali, da so dobljeni organogeli imeli poliHIPE strukturo. Z absorpcijo smo dokazali, da je količina absorbiranih topil pri poliHIPE organogelih večja od bulk organogelov in v nekaterih primerih monoliti absorbirajo več kot 9-kratnik svoje suhe mase. V primeru absorpcije naftnih derivatov so organogeli bili sposobni absorbirati 7-kratnik svoje suhe mase, medtem ko ponovna uporaba organogelov ni bila tako uspešna, saj je bila največja količina absorbiranega naftnega derivata le nekoliko večja kot masa samega monolita.
Keywords: Metatezna polimerizacija z odprtjem obroča (ROMP), poliHIPE, absorpcija, diciklopentadien, norbornen, ciklooktadien
Published: 14.09.2017; Views: 371; Downloads: 69
.pdf Full text (1,89 MB)

2.
3.
Porous beads from multiple emulsions with thiol-ene polymerisation
Stanko Kramer, 2019, master's thesis

Abstract: 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
Keywords: polyHIPE, thiol-ene, suspension polymerisation, porous beads, HIPE
Published: 17.09.2019; Views: 33; Downloads: 10
.pdf Full text (3,56 MB)

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