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V diplomskem delu je predstavljen vpliv raznih parametrov na velikost in velikostno porazdelitev kapljic V/O HIPE emulzij ter posledično na velikost in velikostno porazdelitev primarnih por polistirenskih monolitov. Uporabili smo monomere stiren, divinilbenzen in 2 etilheksilakrilat, pri čemer je divinilbenzen služil kot zamreževalo, 2 etilheksilakrilat pa kot monomerni plastifikator. Z namenom študija HIPE miniemulzij smo spreminjali surfaktant in njegovo količino, porogeno topilo in njegovo količino, iniciator, jakost in čas ultrasonifikacije, količino vodne faze ter čas mešanja emulzije po dodani vodni fazi. Pripravljene emulzije smo okarakterizirali z optičnim mikroskopom pri 400- ali 1000 kratni povečavi, nastale polistirenske monolite pa z vrstičnim elektronskim mikroskopom. S pomočjo FTIR spektrov smo potrdili kemijsko sestavo pripravljenih polistirenov, z adsorpcijsko/desorpcijsko porozimetrijo (BET metodo) pa smo izmerili njihovo specifično površino. Kot porogeno topilo smo uporabili toluen, heksadekan in kombinacijo obeh, pri čemer smo zasledili, da so kapljice emulzij in primarne pore polistirena najmanjše v primeru uporabe 4 ut. % heksadekana. Ker se nastali monoliti med polimerizacijo malenkost skrčijo, smo ugotovili, da je bolje, da se pri pripravi emulzije doda 80 % vodne faze. Pri raziskavah smo preučevali tudi vpliv dveh surfaktantov, Span 80 in Hypermer A70, in njuno količino, od 20 % do 40 %, na velikost kapljic in por. Rezultati so pokazali, da so emulzije med ultrasonifikacijo ostale stabilne v primeru uporabe 40 % dodanega surfaktanta, najmanjše kapljice in pore pa smo dobili pri uporabi surfaktanta Hypermer A70. Pri dodatku 40 % surfaktanta so bile vse emulzije stabilne tudi pri uporabi 100 % jakosti ultrazvoka in pri 75 % jakosti v primeru 20 minutne ultrasonifikacije. Prav tako se je izkazalo, da uporaba kombinacije iniciatorjev TEMED in APS za pripravo takšnih miniemulzij ni primerna. Pri primerjavi različnih časov mešanja emulzije po dodani vodni fazi se je izkazalo, da lahko tudi z daljšimi časi mešanja močno zmanjšamo velikost kapljic emulzije in por polimernih materialov. The thesis presents the influence of various parameters on the size and size distribution of droplets in W/O HIPE emulsions and, consequently, on the size and size distribution of the primary pores of polystyrene monoliths. The monomers that were used are styrene, divinylbenzene and 2-ethylhexylacrylate, wherein the divinylbenzene is used as a crosslinker and 2-ethylhexylacrylate as a monomer plasticizer. In order to study the HIPE miniemulsion was varied the surfactant and its quantity, the progen solvent and its quantity, the initiator, the intensity and time of the ultrasonication, the quantity of the water phase and the time of mixing the emulsion after the water phase was added. Prepared emulsions were characterized using an optical microscope at 400-, or 1000 fold magnification and the resulting polystyrene monoliths by the scanning electron microscope. With the FTIR spectrum the chemical composition of the prepared polystyrene was confirmed, while with the nitrogen adsorption/desorption porosimetry (BET method) specific surface area of monoliths was measured. As a porogen solvent toluene, hexadecane or a combination of both were used and it was observed that the droplets of the emulsion and the primary pores of polystyrene were the smallest in the case when 4 wt. % hexadecane was used. Because the resulting monoliths slightly shrank during the polymerisation, it was found that it is better to add 80 % aqueous phase in the preparation of the emulsion. The effect of two surfactants, Span 80 and Hypermer A70, and their quantity, from 20 % to 40 %, on the size of the droplets and pores was also studied. The results showed that the emulsion during the ultrasonication remained stable in the case of 40 % added surfactant smaller droplets and pores were obtained with the use of the surfactant Hypermer A70. With the addition of 40 % surfactant all emulsions were stable even when using 100 % intensity of ultrasound, and at 75 % intensity in the case of 20-minute ultrasonication. It was also found that the combination of APS and TEMED initiators for the preparation of such miniemulsions is not appropriate. It was discovered that the longer mixing time of emulsion after addition of aqueous phase can significantly reduce the droplet size. |
