magistrsko delo
Patrik Likar (Author), Urška Šebenik (Mentor), Igor Plazl (Thesis defence commission member), Aleš Ručigaj (Thesis defence commission member)

Abstract

Hidrogeli so v zadnjem času predmet številnih raziskav, saj so sposobni absorbirati velike količine vode. Zaradi svoje hidrofilnosti, biorazgradljivosti in kompatibilnosti s človeškimi tkivi so nanocelulozni hidrogeli še posebej zanimivi za morebitno aplikacijo v medicini. V magistrskem delu sem proučeval vpliv zamreževala s cirkonijevimi ioni na lastnosti hidrogelov TEMPO-modificirane nanoceluloze. TEMPO-modificirana nanoceluloza (in ostali anionski polimeri) v prisotnosti kationov zamreži. Do tega pride zaradi elektrostatskih interakcij med kationom in anionskimi funkcionalnimi skupinami na polimeru, katerih posledica je zamreženje polimera v trodimenzionalno strukturo. Posledica zamreženja hidrogela je povišanje vrednosti elastičnega in viskoznega modula ter viskoznosti. Prav tako postane hidrogel dimenzijsko obstojnejši in enostavnejši za rokovanje. V magistrskem delu sem proučeval reološke lastnosti hidrogelov TEMPO-modificirane nanoceluloze, zamreženih s cirkonijevimi ioni. Za zamreženje sem uporabil zamreževalo Bacote, ki je bazična raztopina cirkonijevih ionov. Opazoval sem tudi vpliv pH-vrednosti na reološke lastnosti hidrogela ter vpliv, ki ga ima nanos zamreževala s kapalko ali z razpršilcem na suspenzijo TEMPO-NFC. Ugotovil sem, da se z višanjem deleža zamreževala v hidrogelu povišata njegova viskoznost in elastični odziv. Ugotovil sem tudi, da se hidrogelom v kislem okolju znižata viskoznost in vrednost elastičnega in viskoznega modula, kar je najverjetneje posledica protonacije karboksilatnih funkcionalnih skupin na polimeru. Iz rezultatov je tudi razvidno, da je nanos zamreževala s kapalko učinkovitejši od nanosa zamreževala z razpršilcem zaradi enakomernejše razporeditve zamreževala po površini suspenzije TEMPO-NFC.

Keywords

TEMPO-modificirana nanoceluloza;TEMPO-NFC;zamreženje;cirkonijevi ioni;hidrogeli;reologija;reološke lastnosti;magistrska dela;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL FKKT - Faculty of Chemistry and Chemical Technology
Publisher: [P. Likar]
UDC: 678.5:620.3(043.2)
COBISS: 116920579 Link will open in a new window
Views: 39
Downloads: 28
Average score: 0 (0 votes)
Metadata: JSON JSON-RDF JSON-LD TURTLE N-TRIPLES XML RDFA MICRODATA DC-XML DC-RDF RDF

Other data

Secondary language: English
Secondary title: Crosslinking of TEMPO-modified nanocellulose with zirconium ions
Secondary abstract: Hydrogels have been the subject of much research recently due to their absorption of high amounts of water. Due to their hydrophilicity, biodegradability, and compatibility with human tissue, the nanocellulose hydrogels are of particular interest for possible application in medicine. In the thesis I studied the influence of zirconium ion crosslinker on properties of TEMPO-modified nanocellulose hydrogels. TEMPO-modified nanocellulose (and other anionic polymers) can crosslink in the presence of cations. This is due to electrostatic interactions between cation and anionic functional group on the polymer, which results in crosslinking of the polymer into three-dimensional structure. The crosslinking results in an increase in values of storage and loss modulus and viscosity. It also makes hydrogel more durable and easier to handle. In my master's thesis, I studied the rheological properties of TEMPO-modified nanocellulose hydrogels crosslinked with zirconium ions. For crosslinking, I used Bacote crosslinker, which is a basic solution of zirconium ions. I also observed the effect of pH value on the rheological properties of the hydrogel and the effect of crosslinking with a dropper or spray on the TEMPO-NFC suspension. I found that increasing the proportion of crosslinker in the hydrogel increases its viscosity and elastic response. I also found that hydrogels in an acidic environment reduce the viscosity and value of the elastic and viscous modulus, most likely due to the protonation of carboxylate functional groups on the polymer. The results also show that drip crosslinking was more effective than spray crosslinking due to the better distribution of the crosslinker over the surface of the TEMPO-NFC suspension.
Secondary keywords: TEMPO-modified nanocellulose;crosslinking;zirconium ions;Univerzitetna in visokošolska dela;
Type (COBISS): Master's thesis/paper
Study programme: 1000376
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Fak. za kemijo in kemijsko tehnologijo, smer Kemijsko inženirstvo
Pages: 59 str.
ID: 15849438