Izdelava in vrednotenje nanovlaken na osnovi titanovega dioksida

Konečnik, Katja (author), Kristl, Julijana (mentor), Zupančič, Špela (co-mentor)

Nanovlakna so trdna vlakna s premerom nanometrskih velikosti, teoretično neomejeno dolžino in velikim potencialom za uporabo na številnih področjih. Uporaba nanovlaken iz anorganskih materialov se vedno bolj uveljavlja, med njimi pa največ pozornosti privablja titanov dioksid (TiO2), ki je kemijsko in termično stabilen, ima izjemne optične lastnosti in ni strupen. V naravi obstaja v treh oblikah: anatas, rutil in brukit. Ker se je TiO2 izkazal potencialno uporaben na področju fotokatalizatorjev za uporabo čiščenja odpadnih vod, pri dopolnilnem zdravljenju ran, tkivnem inženirstvu ali fotodinamični terapiji raka, smo v sklopu magistrske naloge želeli izdelati in ovrednotiti nanovlakna na osnovi tega materiala. Prvi korak v magistrski nalogi je bila optimizacija izdelave polimernih nanovlaken z metodo elektrostatskega sukanja iz raztopine polivinil pirolidona (PVP) v absolutnem etanolu. Anorganska nanovlakna s TiO2 smo v drugem koraku pripravili iz polimerne raztopine PVP v etanolu z dodanima titanovim (IV) izopropoksidom (TIP) in ocetno kislino brez in z dodatkom platine ali železa. Izdelana nanovlakna smo izpostavili kontroliranemu procesu segrevanja do visokih temperatur na zraku, da bi dobili nanovlakna iz TiO2, ali s pretokom amonijaka za izdelavo nanovlaken s titanovim oksinitridom (TiOxNy). Proučevali smo vpliv sestave raztopine, procesnih parametrov in temperaturne obdelave vzorcev na morfologijo in sestavo nanovlaken ter njihovo kristalno strukturo z vrstično ter presevno elektronsko mikroskopijo, termogravimetrično analizo, elementarno disperzijsko analizo ter rentgensko praškovno difrakcijo. Ugotovili smo, da se z višanjem deleža PVP in TIP v raztopini premer nanovlaken veča, z višanjem električne napetosti pa manjša. Temperaturna obdelava nanovlaken povzroči izgubo polimera, kar povzroči zmanjšanje premera nanovlaken, zaradi kristalizacije TiO2 pa postane površina bolj hrapava, a nanovlakna ohranijo svojo primarno obliko. Ugotovili smo, da pri segrevanju nad 400 °C TiO2 kristalizira v polimorfni obliki anatas nad 800 °C pa pride do prehoda v rutil. Uspešno smo izdelali tudi nanovlakna s TiOxNy in z dodatkom kovin, kjer se je premer nanovlaken z višjim deležem kovin manjšal. Z elektronsko mikroskopijo smo v nanovlaknih zaznali enakomerno porazdeljene 2 nm delce platine. V magistrski nalogi smo uspešno izdelali nanovlakna iz TiO2 in TiOxNy brez in z dodatkom kovin, ki predstavljajo odlično osnovo za nadaljnjo karakterizacijo nanovlaken za različne namene.

• Language: Slovenian
• Keywords: anorganska nanovlakna, TiO2, elektrostatsko sukanje, termična obdelava
• Work type: Master's thesis/paper
• Organization: FFA - Faculty of Pharmacy
• Year: 2019
• PID: 20.500.12556/RUL-110777
• Publication date in RUL: 19.09.2019

Secondary language

• Language: English
• Title: Development and characterization of nanofibers based on titanium dioxide

Abstract

Nanofibers are solid fibers with a nanoscale diameter, theoretically unlimited length and great potential to be used in many applications. In recent years, nanofibers from inorganic materials have become more established, with titanium dioxide (TiO2) attracting the most attention due to its thermal and chemical stability, excellent optical properties and non-toxicity. In nature, TiO2 has three crystalline phases: anatase, rutile and brookite. TiO2 shows great potential for application as photocatalyst to treat pollutants in wastewater and also in wound healing, tissue engineering and photodynamic therapy in cancer treatment. In this master’s thesis, the aim was to produce and evaluate inorganic nanofibers based on TiO2. The first step in the master’s thesis was to optimize development of polymeric nanofibers with the electrospinning method from polyvinyl pyrrolidone (PVP) solution in absolute ethanol. Inorganic nanofibers with TIO2 were then fabricated from a PVP solution in ethanol with added titanium (IV) isopropoxide (TIP) and acetic acid with and without the addition of platinum and iron. Prepared nanofibers underwent the calcination process in an inert atmosphere to produce TiO2 nanofibers and in an ammonia atmosphere to produce titanium oxynitride (TiOxNy) nanofibers. The effect of composition of the polymer solution, the process parameters and the calcination on nanofiber morphology, the diameter and the crystalline phase by scanning and transmission electron microscopy, thermogravimetric analysis, energy dispersive spectroscopy and x-ray diffraction were investigated. Results showed that the nanofiber diameter increases with increasing PVP and TIP content and decreases with increasing voltage. The calcination process also results in the decrease of the nanofiber diameter due to polymer elimination and in a rough surface due to crystallization of TiO2. During calcination nanofibers retain their primary structure. Results showed that when calcined at 400 °C, TiO2 crystallized in the anatase phase and when calcined above 800 °C the anatase-rutile transformation took place. Nanofibers with TiOxNy and added metals were also produced. Observations suggest that the increasing metal content led to the decrease of the nanofiber diameter. Electron microscopy revealed 2 nm platinum particles uniformly distributed. In the master's thesis, TiO2 and TiOxNy nanofibers with and without the addition of metals were successfully produced, which represents an excellent basis for further characterization of nanofibers for various purposes.

• Keywords: inorganic nanofibers, TiO2, electrospinning method, calcination