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V tem diplomskem delu predstavljamo vpliv več dejavnikov na velikost in porazdelitev por v polimernem materialu pripravljenem iz emulzije z visokim deležem notranje faze. Tako smo spreminjali volumski delež vodne faze in topila, spreminjali smo hitrost mešanja pri pripravi emulzije nato pa smo jo starali. Polimerne materiale smo okarakterizirali z VEM (vrstičnim elektronskim mikroskopom) in optičnim mikroskopom, nato pa s primernim računalniškim programom obdelali slike in izmerili pore. Kot monomera pri emulziji voda v olju (v/o) smo uporabili divinil adipat in tetrakis(3-merkaptopropionat). Uporabljen porogen v našem raziskovalnem delu je bil toluen, kot surfaktant pa smo uporabili kombinacijo Span 65 in PEL 121. Za aktivacijo polimerizacije smo uporabili fotoiniciator Irgacure 819. Polimerizacija poteče po mehanizmu tiol-en kemije. Preučevali smo vpliv dodatka vodne faze na velikost por in ugotovili, da pri 85 vol.% dodane vodne faze nastanejo največje pore v tem polimeru in dobimo tipično poliHIPE strukturo. Prav tako smo spreminjali delež toluena, ker dodajanje porogena vpliva na velikost por v polimeru. Z večanjem dodanega porogena smo povečali pore in zaznali največje pore pri dodatku 50 vol.% porogena. Nato smo spreminjali še hitrost mešanja emulzije od 50 do 250 obratov/min (s korakom 50). Iz rezultatov slik SEM-a in optičnega mikroskopa opazimo, da so pore bistveno večje pri emulzijah, ki smo jih mešali pri nižjih obratih (50 obratov/min, 50 TOPLA), kot pa pri višjih. Največje pore smo izmerili pri 50 (Tvodne faze = 40 °C) TOPLA, najmanjše pa pri 200 obratih/min. S staranjem emulzije smo opazili, da se kapljice vodne faze s časom večajo, za kar sta odgovorna koalescenca in Ostwaldovo zorenje. Ugotovimo, da se vsem pripravljenim emulzijam s časom (do 48h) velikosti kapljic povečajo, dokler emulzija ne postane popolnoma nestabilna in se fazi ločita, kar se zgodi po dveh dneh. In the graduation thesis the influences of some factors on the cell pore size in porous polymer material which was prepared from high internal phase emulsions templating were shown. The volume of aqueous phase, solvent and stirring rate were changed. Polymers were characterized via scanning electron microscopy and optical microscop. Emulsions containing divinyl adipate and tetrakis(3-mercaptopropionate) as the monomers were prepared. Suitable solvent was toluene, while the surfactant was used mixture of Span 65 and PEL 121. Than we added photoiniciator and photopolymerisation was carried out. Polymerisation mechanism occurring is thiol-ene step-growth polymerisation. The effects of adding aqueous phase to a solution of monomers were studied. The optimal aqueous content of HIPE was 85 vol. %, meaning that in this case the droplet size increased the most. Also the volume of toluene was changed, because the porogen has an effect on pore size. The optimal toluene content in HIPE was 50 vol. %. The rate of stirring was found to be between 50 rpm to 250 rpm. Emulsions were analyzed with optical microscope and polymers with scanning electron microscope and both gave us comparable results. The size of internal phase droplets increased with decreasing stirring rate and the same occurred with pores in polymer. Pore enlargement was measured at 50 rpm and heated internal phase to 40°C and the reduction of stirring to 200 rpm. Finaly we studied the effects of emulsions aging. Internal phase droplets size increase with aging of emulsion mainly due to Ostwald rippenig and coalescence. We concluded that emulsions which were aged up to 48 hours were stable but after that phases separated. |
