| Sažetak | Celuloza je najrasprostranjeniji prirodni polimer. Sve se više istražuje radi korištenja u medicinske i industrijske svrhe, prije svega zbog svoje biorazgradivosti, biokompatibilnosti, široke dostupnosti i neškodljivosti. Celuloza je sastavljena od linearnih lanaca glukoze koji mogu imati od nekoliko stotina do nekoliko tisuća monomernih jedinica povezanih ß-(1→4) glikozidnom vezom što joj i omogućuje stvaranje dugih lanaca. Svaka molekula celuloze ima 3 hidroksilne skupine koje joj omogućuju razne modifikacije, te umreživanje lanaca i pripravu hidrogelova. Cilj ovog rada je sintetizirati hidrogelove celuloze graftirane sa poli(dimetilaminoetil-metakrilatom) (PDMAEMA) i umrežene sa N,N-metilen-bis-amidom (MBA) na dva načina; izravnom sintezom i zračenjem, te usporediti njihova svojstva. Monomer DMAEMA koji se ugrađuje u hidrogel ima u svojem sastavu amino skupina koja je osjetljiva na promjenu pH. Tako se dobiveni hidrogel potencijalno se može koristit kao senzor ili nosač primjerice u medicini, farmaciji, poljoprivredi i slično. Graft kopolimerizacija dimetilaminoetil-metakrilata (DMAEMA) na celulozu provedena je u otapalu N,N-dimetil acetamid/LiCl uz peroksidni inicijator Trigonox 21 pri temperaturi od 90 °C, te uz N,N-metilen-bis-akrilamid (MBA) kao umreživalo. Za usporedbu, ti su uzorci naknadno ozračeni da se vidi utjecaj na učinkovitost umrežavanja hidrogelova. Kod sinteze zračenjem, potrebne kemikalije su pomiješane i stavljene izravno na zračenje, bez prethodnog zagrijavanja. Priređeni hidrogelovi podijeljeni su u dvije serije. U uzorcima serije 1 omjer celuloze i DMAEMA je 1:3, a celuloze i MBA 5:1, dok je u uzorcima serije 2 omjer celuloze i DMAEMA 1:5, a omjer celuloze i MBA 3:1 i 2:1. Svi uzorci obje serije su zračeni dozama zračenja od 10, 30 i 100 kGy. Sintetizirani hidrogelovi karakterizirani su infracrvenom spektroskopijom kako bi se odredio udio graftiranog metakrilatnog polimera u hidrogelu. Hidrogelovima je određivan stupanj bubrenja u deioniziranoj vodi, s tim da su uzorci sušeni na dva načina; u sušioniku i u kriostatu. Promatran je i utjecaj različite metode sušenja na stupanj bubrenja. Temeljem omjera intenziteta vrpci pri 1724 i 897 cm^-1 utvrđeno je da najveći udio PDMAEMA ima hidrogel 2-3 iz serije 2 čiji je omjer celuloze i DMAEMA 1:3, a doza zračenja kojom je hidrogel zračen je 100 kGy. Udio PDMAEMA iznosi 107,45. Provedbom pokusa bubrenja najveći stupanj bubrenja kod uzoraka sušenih u sušioniku utvrđen je u hidrogelu 1-6 iz serije 1 čiji je omjer celuloze i MBA 5:1, a doza zračenja 100 kGy. Stupanj bubrenja iznosi 2,1. Kod sfera sušenih u kriostatu najveći stupanj bubrenja ima hidrogel 1-6, također iz serije 1 čiji stupanj bubrenja iznosi 7,8. |
| Sažetak (engleski) | Cellulose is the most widely spread natural polymer. It is being intesively researched for use in medical and industrial purposes, above all for its biodegradebility, biocompatibility, wide spread availability and non toxicity. Cellulose is made of linear chains of glucose that may have a wide range of monomer units, ranging from several hundreds to several thousands units, mutually interconnected with β-(1→4) glycosidic bond which enables creation of long polymer chains. Every cellulose mollecule has three hydroxyl groups that allow different modifications, chain crosslinking and hydrogel synthesis. The aim of this study is to synthetize cellulose hydrogels grafted with N,N-diethylaminoethyl metacrilate (DMAEMA) and crosslinked with N,N-methylenbisacrilamide (MBA) on two different ways and to compare their properties. One of methods is direct synthesys in solution and the other one is synthesys by X-ray irradiation. Monomer DMAEMA that was used in hydrogel synthesis has amino group in its composition which is pH sensitive. That way synthetized hydrogel can be used as sensor, carrier, in medicine, pharmacy, agriculture and etc. Graft copolymerization of DMAEMA onto cellulose is carried out in N,N-dimethyacetamide/LiCl solvent mixture with Trigonox 21 peroxide iniciator at temperature of 90˚C, and with N,N'-methylenebisacrilamide as crosslinker. For a comparison, these samples were later irradiated to observe the impact of hydrogels crosslinking efficiency. . By irradiation synthesys, all necessary chemicals were mixed and were put in place to be irradiated, without prior heating. Hydrogels were divided into two series named serial 1 and serial 2. Serial 1 samples had cellulose to DMAEMA ratio of 1:3, and cellulose to MBA ratio of 5:1, while serial 2 samples had cellulose to DMAEMA ratio of 1:5 and cellulose to MBA ratio of 3:1 and 2:1. Samples from both series were irradiated by 10, 30 and 100 kGy. Synthetized hydrogels were characterised by infrared spectroscopy in order to determine share of grafted metacrilate polymer in hydrogel. Hydrogels were swelled in deionised water in order to determine swelling degree. Samples were dryed using two different methods; in dryer and in cryostat. Effect of different drying method on swelling degree was observed. As far as grafted PDMAEMA is concerned, using peaks intensity ratios at 1724 and 897 cm^-1 it is found that largest amount of grafted PDMAEMA is found in hydrogel 2-3, serial 2 whose cellulose to DMAEMA ratio is 1:5, and irradiation dose is 100 kGy. Amount of grafted PDMAEMA is 107,45. By determining maximum swelling degree, it is found that largest maximum swelling degree in group of samples dryed in a dryer has hydrogel 1-6 (2,1) from serial 1, whose cellulose and MBA ratio is 5:1 and irradiation dose is 100 kGy. In the group of samples dryed in a cryostat , largest swelling degree has hydrogel 1-6 (7,8) from serial 1, whose cellulose to MBA ratio is also 5:1, and irradiation dose is 100 kGy. |
