Morfološke značilnosti poli(glicidil metakrilat-ko-etilen glikol dimetakrilatov) pripravljenih iz emulzij z visokim deležem notranje faze

diplomsko delo

Doroteja Žibert (Author), Peter Krajnc (Mentor)

Abstract

V diplomskem delu smo proučevali vpliv različnih dejavnikov na morfologijo materialov, pripravljenih iz emulzij z visokim deležem notranje faze. Pripravljali smo emulzije tipa voda v olju z GMA/EDGMA (ali EDMA) v različnih razmerjih. Pripravljene emulzije smo analizirali s svetlobnim mikroskopom, monolite pa z vrstičnim elektronskim mikroskopom. Najprej smo proučevali vpliv staranja emulzij. Ugotovili smo, da se velikost kapljic notranje faze v emulziji s časom zaradi koalescence in Ostwaldovega zorenja veča. Posledično so pore v monolitnem materialu, pripravljenem iz starane emulzije večje, kot v materialu, polimeriziranem iz na novo pripravljene emulzije. Velikost kapljic v emulziji se je povečala od približno 1-2 %m na 5-6 % m v približno treh tednih. Po tem času se je začelo vidno ločevanje faz emulzije. Izmerjeno povečanje je sovpadalo z velikostjo por v polimernih monolitnih materialih, pripravljenih iz opazovanih emulzij. Nato smo opazovali spremembe pri zmanjšanju količine surfaktanta. Uporabljali smo surfaktant PEL 121. Po zmanjšanju količine za polovico smo opazili, da je velikost kapljic takoj po mešanju približno enkrat večja kot v vzorcih z običajno količino surfaktanta. Nadaljnje povečevanje kapljic je potekalo enako hitro kot pri kontrolnih vzorcih, vendar pa je bila maksimalna dosežena velikost kapljic, 5-6 % m, zaradi začetne razlike dosežena že po enem tednu. Kasneje se je začelo že vidno ločevanje faz emulzije. Nekateri od pripravljenih monolitnih materialov teh vzorcev niso imeli značilne sferično porozne strukture, zato je bilo merjenje oteženo, rezultati pa nezanesljivi. Nazadnje smo opazovali še vplive dodajanja topil. Uporabili smo topili metanol in 2-propanol. V emulzijah smo opazili povprečno povečanje kapljic za 2 %m glede na kontrolo. To se je odražalo tudi na nekaterih pripravljenih monolitih, pri drugih pa smo ponovno opazili velika odstopanje od značilne porozne strukture, zato meritev nismo mogli opraviti. Kot najbolj konsistentno se je za povečevanje por izkazalo staranje emulzije, druge metode zaradi velike nestabilnosti emulzij niso dale zadovoljivih rezultatov.

Keywords

kemija;polimeri;emulzije;notranja faza;velikost por;koalescenca;diplomska dela;

Data

Language:	Slovenian
Year of publishing:	2012
Source:	Maribor
Typology:	2.11 - Undergraduate Thesis
Organization:	UM FNM - Faculty of Natural Sciences and Mathematics
Publisher:	[D. Žibert]
UDC:	54(043.2)
COBISS:	19106568
Views:	2890
Downloads:	163
Average score:	0 (0 votes)
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Other data

Secondary language:	English
Secondary title:	Morphological properties of poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) prepared from high internal phase emulsions
Secondary abstract:	In the graduation thesis we examined the effects of different factors on the materials prepared from high internal phase emulsions. We prepared water in oil emulsions GMA/EGDMA (or EDMA) in different proportions. The prepared emulsions were analysed with an optical microscope and the monoliths with a scanning electron microscope. Firstly, we studied the effects of the aging of emulsions. We discovered that the size of the internal phase droplets in the emulsion increases with time due to coalescence and Ostwald ripening. The pores in material prepared from aged emulsion are consequently larger than the ones in material prepared from freshly prepared emulsions. Droplet size increased from approximately 1-2 % m to 5-6 % m in approximately 3 weeks. After that period visual separation of the emulsion phases occurred. The measured enlargement of droplets was consistent with the size of voids in material prepared from the observed emulsions. After that we studied changes when decreasing the amount of surfactant. The surfactant used was PEL 121. After reducing the amount of surfactant by a half, the average size of droplets in emulsion right after stirring was twice the size of droplets in emulsions with a normal amount of surfactant. The further increase of droplets was as fast as in the control samples, but due to the initial difference, the maximal size of 5-6 %m was reached after only one week. After that visual separation of emulsion phases occurred. Some of the prepared monolith materials did not have typical spherical porous structure, therefore the measurements were difficult and the results unreliable. Lastly we studied the effects of adding solvents. Solvents used were methanol and 2-propanol. The increase of droplet size in emulsions was 2 % m compared to the control. The results did reflect in some of the prepared monoliths, whereas in others big deviations from standard structures were again observed, therefore the measurements could not be made. The most consistent procedure for pore increase found was aging the emulsions; other explored methods did not give satisfactory results due to great instability of emulsions.
Secondary keywords:	polymer;high internal phase emulsions;void size;coalescence;Ostwald ripening;
URN:	URN:SI:UM:
Type (COBISS):	Undergraduate thesis
Thesis comment:	Univ. v Mariboru, Fak. za naravoslovje in matematiko, Oddelek za kemijo
Pages:	X, 48 f.
Keywords (UDC):	mathematics;natural sciences;naravoslovne vede;matematika;chemistry;crystallography;mineralogy;kemija;
ID:	19897