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Nanokompoziti uključuju širok spektar materijala, koji se sastoje od više izrazito različitih komponenata, izmiješanih na nanometarskoj skali. Svojstva nanokompozita ne ovise samo o konstituentima, već i o morfologiji i karakteristikama na sučelju faza. Istraživanje je provedeno na filmovima načinjenim od nanokompozita s antimikrobnim djelovanjem. U netoksičnu polimernu matricu od poli(vinil-alkohola) (PVA), topljivu u vodi, dodane su organske nanočestice hitozana (CS) i anorganske nanočestice cinkova oksida (ZnO) poznate po antimikrobnom učinku. Mješavine PVA i CS kemijski su umrežene glutaraldehidom (GA). Za karakterizaciju mješavina korištene su sljedeće tehnike: dinamičko-mehanička analiza (DMA), diferencijalna pretražna kalorimetrija (DSC), pretražna elektronska mikroskopija uz energijski razlučujuću rendgensku spektroskopiju (SEM/EDS), mikroskopija atomskih sila (AFM) te infracrvena spektroskopija s Fourierovom transformacijom (FTIR). Također, ispitan je i utjecaj nanočestica i umreženosti na permeaciju malih molekula dušika kroz dobivene nanokompozitne filmove. Permeacija je ispitana time-lag metodom. Utvrđeno je da se dinamički modul elastičnosti i faktor prigušenja vibracija mogu krojiti variranjem udjela dodanih komponenata. Između PVA, CS i ZnO vidljiva je interakcija što omogućuje dobru mješljivost. Hitozan smanjuje stupanj kristalnosti PVA, a formiraju se vodikove veze između PVA i CS. Dodatkom ZnO u polimernu matricu smanjuje se intenzitet α relaksacije u mehaničkom spektru, što ukazuje na dobru povezanost i stvaranje međufaze slabije pokretljivosti na sučelju s polimernom matricom. Dodavanjem CS i ZnO u PVA poboljšavaju se barijerna svojstva. Nanocomposites encompass a large variety of materials made of distinctly dissimilar components and mixed on a nanometer scale. Their properties depend not only on the properties of their constituents, but also on their morphology and interfacial characteristics. This research was conducted on films made of nanocomposites with antimicrobial activity. Organic nanoparticles (NPs) of chitosan and inorganic nanoparticles of ZnO, both known for their antimicrobial effect are added into a water soluble non-toxic PVA matrix. Blends of PVA and CS were chemically crosslinked with glutaraldehyde (GA). Characterization of blends was performed using dynamic-mechanical analysis (DMA), differential scanning calorimetry (DSC), scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM/EDS), atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR). The influence of nanoparticles and crosslinking on the permeation of small nitrogen molecules through the obtained nanocomposite films was also investigated. Permeation was examined by the time-lag method. It was found that the dynamic modulus of elasticity and the vibration damping factor can be tailored by varying the proportion of added components. An interaction between PVA, CS and ZnO was confirmed, which allows good miscibility. Chitosan reduces crystallinity degree of PVA, and hydrogen bonds are formed between PVA and CS. The addition of ZnO to the polymer matrix reduces the intensity of α relaxation in the mechanical spectrum, which indicates a good connection and the formation of an interphase with reduced molecular mobility at the interface with the polymer matrix. The addition of CS and ZnO to PVA improves barrier properties.

U radu je istaživan utjecaj UV zračenja na nanokompozite polistirena i cinkovog oksida. Pripremljeni su nanokompoziti na dva različita načina iz otopine (PSS) i iz taline (PSm). Nanokompoziti su sadržavali različite volumne udjele nanočestica (0, 0.1%, 0.3%, 0.5 % i 1%). Korištene su dvije dimenzije nanočestica i to 10-30 nm i 40-100 nm. Istraživanja vibracijske dinamike su pokazala da 0.5% ZnO u PSS nanokompozitima i 1% ZnO u PSm nanokompozitima znatno smanjuje degradaciju. Dodavanje ZnO nanočestica također poboljšava toplinska svojstva. Provedeno istraživanje pokazuje moguću primjenu ovih materijala za detekciju UV zračenja. In this BSc Thesis UV radiation effects on nanocomposites made from polystyrene and zinc oxide were explored. Two different methods were used to prepare nanocomposites, using solution and melt. Nanocomposites contained different volume fractions of nanoparticles (0, 0.1%, 0.3%, 0.5 % i 1%). Two dimensions of nanoparticles were used, 10-30 nm and 40-100 nm. Investigation of vibrational dynamics showed that PSS nanocomposites with 0.5% ZnO and PSm nanocomposites with 1% ZnO degraded significantly less. Inclusion of nanoparticles also enhances thermal properties. This investigation showed possible application of these materials for UV radiation detection.

Iz literature je poznato da listići cinkova oksida imaju dobru katalitičku aktivnost. Stoga je u ovom radu teorijski obrađena primjena ZnO nanočestica za katalizu te različite metode pripreme ZnO nanočestica. Cilj eksperimentalnog dijela rada bio je dobiti različite oblike morfologije ZnO na staklenoj pločici. Izlaganjem pločice stabilnoj otopini cinkova acetata dihidrata u metanolu dobiveni su slojevi listićave strukture, za koje je infracrvena spektroskopija pokazala da su vjerojatno miješani cinkov acetat-hidroksid. Kalciniranjem tih slojeva kristalizira ZnO, dok je listićava morfologija zadržana. Također su izvlačene prevlake iz iste otopine na staklenu pločicu i ispitivan je utjecaj broja slojeva na morfologiju. Morfologija tako dobivenih slojeva nije ovisila o konačnoj debljini prevlake i pokazala je finu kristalnu strukturu nakon kalciniranja na 500 °C. From the literature it is known that zinc oxide flakes have a good catalytic activity. Therefore, the application of ZnO nanoparticles for catalysis as well as various preparation methods of ZnO nanoparticles are theoretically analyzed in this paper. The goal of the experimental part of this paper was to get various morphologies of ZnO on a glass plate. By exposing the plate to a stable solution of zinc acetate dihydrate in methanol, layers of leaf-like structure were made, for which the infrared spectroscopy showed that they are probably mixed zinc acetate-hydroxide. By calcinating these layers crystallize into ZnO, while the leaf-like morphology is preserved. Also, coatings were drawn from the same solution on a glass plate and the impact of the number of layers on the morphology was examined. The morphology of thus obtained layers was not dependent on the thickness of the final coating, and showed a fine crystal structure after calcination at 500 °C.