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Biopolymer composites with ZnO-nanoparticles
No full textPolimeri se danas najčešće dobivaju iz nafte te imaju negativan utjecaj na okoliš. Kako bi se negativan utjecaj na okoliš smanjio, sve češće se koriste biopolimeri. Jedan od često korištenih biopolimera je polilaktid. Iako je danas biomasa za izradu biopolimera lako dostupna, proizvodnja biopolimera je još uvijek skupa što ograničava proizvodnju. Svojstva polimernih materijala mogu se poboljšati dodatkom punila čime se dobiva polimerni kompozit. U ovom radu proučen je utjecaj različitih udjela ZnO nanočestica u kompozitu na osnovi biorazgradivog polilaktida. Uzorci su pripremljeni u Brabender gnjetilici nakon čega su prešani na hidrauličkoj preši te su podvrgnuti različitim metodama karakterizacije. Ispitivana su mehanička i toplinska svojstva pripremljenih kompozita, a goniometrom je određen kontaktni kut potreban za izračun površinske energije pripremljenih kompozita. Mehanička svojstva uzoraka ispitana su rasteznim ispitivanjem na mehaničkoj kidalici. Diferencijalnom pretražnom kalorimetrijom određeni su fazni prijelazi, a promjena toplinske stabilnosti određena je termogravimetrijskom analizom materijala. Provedene analize pokazale su kako dodatak nanopunila utječe na svojstva čistog polilaktida. Rezultati mjerenja kontaktnog kuta ukazuju na hidrofobnu površinu PLA te hidrofilnu površinu ZnO. Mehanička ispitivanja pokazala su da se dodatkom punila može utjecati na svojstva polimerne matrice te da se pripremljeni kompoziti kidaju krtim lomom. DSC analiza je pokazala da punilo utječe i na staklište kompozita ali i na temperaturu hladne kristalizacije. TGA analizom potvrđeno je da se s promjenom udjela punila mijenjaju svojstva materijala.Although biomass for biopolymer production is readily available today, biopolymers are still expensive to produce, which limits production. Biopolymers are increasingly used to reduce the negative impact on the environment. Polylactide is one of the most commonly used biopolymers. The properties of polymer materials can be improved by adding fillers, resulting in a polymer composite. In this work, the influence of different proportions of ZnO nanoparticles in composites based on biodegradable polylactide was investigated. The samples were prepared in a Brabender Kneader, then compacted in a hydraulic press and characterized using different techniques. The mechanical and thermal properties of the composites prepared were studied, and a goniometer was used to estimate the contact angle required to calculate the surface energy of the composites. The mechanical and thermal properties of the specimens were evaluated, and the mechanical properties of the specimens were studied using tensile tests on a mechanical testing machine. Differential scanning calorimetry was used to identify phase transitions, and the change in thermal stability was determined by thermogravimetric analysis of the material. The phase transitions were determined by differential scanning calorimetry, and the analyses performed showed that the addition of nanofillers affects the properties of pure polylactide. The results of contact angle measurements indicate a hydrophobic surface of PLA and a hydrophilic surface of ZnO. Mechanical tests showed that the properties of the polymer matrix can be affected by the addition of fillers and that the prepared composites have a brittle fracture. DSC analysis showed that the filler affects the glass transition temperature of the composite as well as the cold crystallization temperature. The TGA analysis confirmed that with a change in the filler content, the material properties also change
Preparation of novel nitro-substituted benzothiazole derivatives
No full textU sklopu završnog rada provedena je mehanokemijska sinteza O-alkiliranih 6-nitro-supstituiranih derivata benzotiazola 5a‒10a, 5b‒10b, 5c‒10c, kao i sinteza potpomognuta mikrovalovima benzotiazolnih derivata supstituiranih 1,2,3-1H-triazolom 11a–11c. Ključni prekursori 4-(6-nitrobenzotiazol-2-il)fenola 4a–4c pripravljeni su u glicerolu reakcijom bis(2-amino-5-nitrofenil)disulfida 3 i odgovarajućeg supstituiranog 4-hidroksibenzaldehida. Sinteza ciljanih O-alkiliranih 6-nitro-supstituiranih benzotiazola (5a‒10a, 5b‒10b, 5c‒10c) provedena je iz odgovarajućih fenolnih derivata (4a–4c) u reakciji s određenim alkil-halogenidom u kugličnom mlinu. Sinteza 1,2,3-1H-triazolnih derivata benzotiazola 11a–11c provedena je Cu(I) kataliziranom regioselektivnom 1,3-dipolarnom cikloadicijom iz odgovarajućih terminalnih alkina benzotiazola 5a–5c i trimetilsililazida. Navedenim „klik“ reakcijama koje su provedene u mikrovalnom reaktoru nisu izolirani ciljani produkti. Strukturna i spektroskopska karakterizacija novopriređenih spojeva provedena je 1H i 13C NMR spektroskopijom.As part of this paper, mechanochemical synthesis of O-alkylated 6-nitro-substituted benzothiazole derivatives 5a‒10a, 5b‒10b, 5c‒10c was performed, as well as microwave-assisted synthesis of benzothiazole derivatives substituted with 1,2,3-1H-triazole 11a–11c. Key intermediates 4-(6-nitrobenzothiazol-2-yl)phenols 4a–4c were prepared in glycerol by reaction of bis (2-amino-5-nitrophenyl)disulfide 3 and the corresponding substituted 4-hydroxybenzaldehyde. The synthesis of targeted O-alkylated 6-nitro-substituted benzothiazoles (5a‒10a, 5b‒10b, 5c‒10c) was performed from the corresponding phenolic derivatives (4a–4c) and alkyl halides in a ball mill. The synthesis of 1,2,3-1H-triazole derivatives of benzothiazole 11a–11c was performed by regioselective Cu(I) catalyzed 1,3-dipolar cycloaddition from the corresponding terminal alkynes of benzothiazole 5a–5c and trimethylsilylazide. These "click" reactions performed in the microwave reactor did not yield the target products. Structural and spectroscopic characterization of the newly prepared compounds was performed by 1H and 13C NMR spectroscopy
Development of an integrated microsystem for the continuous extraction of the enzyme laccase
No full textPročišćavanje enzima dugotrajan je, skup i zahtjevan proces koji najčešće rezultira s niskim prinosom i gubitkom aktivnosti enzima. Ekstrakcijske metode su među najraširenijim metodama pročišćavanja različitih molekula, međutim upotreba konvencionalnih otapala, kao što su organska otapala, dovodi do denaturacije enzima. Upotreba vodenih dvofaznih sustava u svrhu pročišćavanja biomolekula, pokazala se učinkovitom i ekološki prihvatljivom metodom. Između različitih vodenih dvofaznih sustava, posebnu pažnju privlače vodeni dvofazni sustavi na bazi eutektičnih otapala (engl. Deep Eutectic Solvents, DES) zbog svoje niske toksičnosti, visoke biorazgradivosti i ekonomičnosti. Posljednjih godina, pozornost se usmjerava i na upotrebi mikroekstraktora u svrhu pročišćavanje biomolekula zbog intenzifikacije proces i manje vjerojatnosti narušavanje strukture biomolekula. U ovom radu razvijen je integrirani sustav serijski povezanog mikroekstraktora i mikroseparatora za kontinuiranu mikroekstrakciju proteina, odnosno ekstrakciju enzima lakaza porijeklom iz Trametes versicolor korištenjem vodenog dvofaznog sustava na bazi DES-a. Ukupno je sintetizirano i karakterizirano 15 DES-ova. U seriji šaržnih ekstrakcija ispitan je utjecaj sastava DES-ova i koncentracije soli (K2HPO4) na učinkovitost ekstrakcije enzima lakaza. Sustav koji se sastojao od eutektičnog otapala kolin-klorid:propilen-glikol:cinkov diklorid 1:4:0,02 (ChCl:PG:ZnCl2 1:4:0,02) i vodene otopine K2HPO4 koncentracije γ = 0,5 g/mL pokazao se najučinkovitijim sustavom za ekstrakciju enzima lakaza. U sljedećem koraku, korištenjem odabranog sustava, ispitan je utjecaj koncentracije enzima na učinkovitost ekstrakcije, a dobiveni rezultati pokazali su da povećanje koncentracije enzima pozitivno utječe na učinkovitost ekstrakcije. U svrhu intenzifikacije procesa, ekstrakcija je provedena u mikroekstraktoru gdje su ispitani utjecaj promjera kanala i vremena zadržavanja na učinkovitost ekstrakcije. Najveća učinkovitost ekstrakcije enzima u mikroekstraktoru (d = 500 μm) iznosila je E = 88,34 ± 1,04 %, a ostvarena je za vrijeme zadržavanja od τ = 12 s. Proces ekstrakcije u mikroekstraktoru uspješno je opisan 2D matematičkim modelom. Nakon optimizacije procesa ekstrakcije, mikroekstraktor je serijski spojen s mikroseparatorom u kojem je provedena uspješna separacija ekstraktne i rafinatne faze. Na samom kraju, razvijena metoda ispitana je na sirovom enzimu lakaza proizvedenog fermentacijom Trametes versicolor, a ekstrahirani enzim upotrjebljen je za uklanjanje tekstilne boje na bazi anilina.Enzyme purification is a lengthy, expensive, and demanding process that usually results in low yield and loss of enzyme activity. Extraction procedures are among the most widely used methods for purifying various molecules. However, the use of conventional solvents, such as organic solvents, leads to denaturation of enzymes. The use of aqueous two-phase systems (ATPS) to purify biomolecules has been shown to be an effective and environmentally friendly method. Among the various ATPS, ATPS based on deep eutectic solvents (DES) are attracting special attention due to their low toxicity, high biodegradability, and cost-effectiveness. In recent years, attention has also focused on the use of microextractors for biomolecule purification because they intensify the process and are less likely to disrupt the structure of biomolecules. In this work, an integrated system of microextractor and microseparator connected in series was developed for continuous microextraction of proteins, i.e., extraction of the enzyme laccase from Trametes versicolor, using an ATPS based on DES. A total of 15 DESs were synthesized and characterized. In a series of batch extractions, the influence of DES composition and salt concentration (K2HPO4) on the efficiency of laccase enzyme extraction was investigated. The system consisting of the eutectic solvent choline-chloride:propylene glycol:zinc dichloride 1:4:0.02 (ChCl:PG:ZnCl2 1:4:0.02) and an aqueous solution of K2HPO4 with a concentration of γ = 0.5 g/mL proved to be the most efficient system for laccase enzyme extraction. In the next step, the influence of enzyme concentration on extraction efficiency was tested using the selected system. The obtained results showed that increasing the enzyme concentration positively affected the extraction efficiency. To intensify the process, the extraction was performed in a microextractor, and the influence of the channel diameter and residence time on the extraction efficiency was studied. The highest efficiency of enzyme extraction in the microextractor (d = 500 μm) was E = 88.34 ± 1.04 % and it was achieved at a residence time of τ = 12 s. The extraction process in the microextractor was successfully described by a 2D mathematical model. After optimization of the extraction process, the microextractor was connected in series with a microseparator, in which the extract and raffinate phases were successfully separated. At the very end, the developed method was tested on the crude laccase enzyme produced by the fermentation of Trametes versicolor, and the extracted enzyme was used to remove the aniline-based textile dye
Monitoring of the efficiency of topical treatment for concrete applied to prevent corrosion of rebar
No full textKorozija skraćuje vijek trajanja i upotrebnu vrijednost sirovina i proizvoda, poskupljuje njihovo održavanje, uzrokuje nesreće i pogoršava kvalitetu proizvoda. Gubici koji nastaju nisu samo troškovi zamjene ili popravka već i neizravni troškovi poput zaustavljanja pogona, smanjenja stupnja efikasnosti ili onečišćenje proizvoda i okoliša. Veliki dio troškova mogao bi se izbjeći primjenom odgovarajućih metoda zaštite od korozije. Za svrhu ovog ispitivanja, čiji je cilj bio odrediti djelotvornost površinskih premaza, pripremljena su tri uzorka koji predstavljaju armirani beton. Jedan je uzorak površinski tretiran SILRES® BS 170 nerazrijeđenim hidrofobnim premazom za impregnaciju armiranog betona, a drugi MCI®-2018 premazom od 100% silana koji sadrži migrirajuće inhibitore korozije. Provedeno je mjerenje potencijala otvorenog strujnog kruga te elektrokemijska impedancijska spektroskopija, a spektri su prikazani Nyquistovim i Bodeovim grafovima. Usporedbom svih rezultata zaključeno je da su obje vrste premaza vrlo djelotvorni površinski tretmani. Površinski tretman SILRES® BS 170 posebno je učinkovit u vlažnim, a MCI®-2018 u kloridnim uvjetima.Corrosion shortens the service life and useful value of raw materials and products, makes their maintenance more expensive, causes accidents and deteriorates the quality of products. The resulting losses are not only replacement or repair costs, but also indirect costs such as plant shutdowns, reductions in efficiency, or product and environmental pollution. A large part of the costs could be avoided by applying appropriate corrosion protection methods. For the purpose of this test, the aim of which was to determine the effectiveness of surface coatings, three samples representing reinforced concrete were prepared. One sample was surface-treated with SILRES® BS 170, undiluted hydrophobic coating for impregnation of reinforced concrete, and the other with MCI®-2018, 100% silane coating containing migrating corrosion inhibitors. The open circuit potential was measured and electrochemical impedance spectroscopy was performed, and the spectra were shown with Nyquist and Bode graphs. By comparing all results, it was concluded that both types of coatings are very effective surface treatments. The surface treatment SILRES® BS 170 is particularly effective in wet conditions, and MCI®-2018 in chloride conditions
Hydrothermal synthesis of manganites
No full textModerno društvo orijentirano je prema razvoju novih, visokoučinkovitih tehnologija kojima bi se umanjili negativni utjecaji fosilnih goriva na ekologiju i ekonomiju te omogućio daljnji održivi razvoj. Perovskiti, materijali koji od 50-ih godina 20. stoljeća sve više privlače pozornost znanstvenika zbog specifičnih svojstava, još uvijek se ne upotrebljavaju na komercijalnoj razini. Potencijal njihove praktične uporabe leži u izvrsnim električnim, magnetskim i katalitičkim svojstvima. Cilj ovoga rada bio je istražiti mogu li se nanočestice lantanova manganita sintetizirati hidrotermalnom metodom i odrediti optimalne uvjete njihove sinteze. Pripravljeni uzorci analizirani su pomoću termogravimetrijske (TGA) i rendgenske difrakcijske analize (XRD), infracrvene spektroskopije s Fourierovom transformacijom (FTIR) i pretražne elektronske mikroskopije (SEM). Rezultati hidrotermalne sinteze uspoređeni su s rezultatima koprecipitacijske sinteze i mikrovalno potpomognute hidrotermalne sinteze. Utvrđeno je da u sva tri slučaja lantanov manganit nije nastao direktno nakon sinteze, već je dobivene prekursore bilo potrebno žariti. Ni u tom slučaju ne nastaje čisti lantanov manganit, već nastaju i lantanovi i manganovi oksidi. Lantanov oksid može se ukloniti otapanjem da bi se dobio čisti LaMnO3. Nastali LaMnO3 ima veličinu kristalita u rasponu 16 – 54 nm, što je i dvostruko manje nego kod limunskog postupka.Modern society is orientated towards the development of novel, highly-efficient technologies to reduce the negative impact of fossil fuels on the ecology and economy and to provide further sustainable development. Perovskites, materials that have increasingly attracted the attention of scientists since the 1950s due to their specific properties, are still not used on a commercial level. The great potential for their practical use lies in their exceptional electrical, magnetic and catalytic properties. The aim of this work is to investigate whether lanthanum manganite nanoparticles can be synthesized by hydrothermal method and to determine the optimal synthesis conditions. Prepared samples were analysed by thermogravimetric (TGA) and X-ray diffraction analysis (XRD), infrared spectroscopy with Fourier transformation (FTIR) and scanning electron microscopy (SEM). The results of hydrothermal synthesis were compared with the results obtained by coprecipitation synthesis and microwave-assisted hydrothermal synthesis. It is established that in all three cases lanthanum manganite was not formed directly after synthesis, but the obtained precursors had to be annealed. Pure lanthanum manganite was not formed even after annealing, since lanthanum and manganese oxides were also formed. The lanthanum oxide can be removed by dissolution to give pure LaMnO3. The resulting LaMnO3 has a crystallite size in the range 16 – 54 nm, which is twice as small as in the citrate process
Investigation on effect of egg shell on properties of polyethylene composites
No full textŽelja i potreba za smanjenjem ekoloških problema kao što su: zagađenje okoliša, nagomilavanje smeća, iskorištavanje naftnih derivata, prekomjerno ispuštanje CO2, plastika u morima i na kopnu, bile su razlog priprave novih materijala, koji će imati poboljšana svojstva u odnosu na pojedinačne komponente od kojih se sastoje. Teži se razvitku kompozita s bio-osnovom, poželjno biorazgradljivim, koji bi zamijenili ili barem donekle zamijenili već postojeće tradicionalne materijale. Polietilen je jedan od najpoznatijih polimera na naftnoj osnovi, a umješavanjem ljuskica jajeta, mogla bi se poboljšati njegova mehanička svojstva. Poznati su razni oblici ovog polimera sa širokim rasponom primjene. Uzorci čistog LLDPE-a, ljuskica jajeta i uzoraka LLDPE/LJJ biokompozita, ispitvani su tehnikama diferencijalne pretražne kalorimetrije (DSC) i infracrvene spektroskopije s Fourierovom transformacijom (FTIR). DSC tehnikom se utvrdilo da pri ciklusu zagrijavanja dodatak LJJ ne uzrokuje značajne promjene unutar kristalne faze LLDPE-a, odnosno ne utječe na veličinu kristala i njihovu uređenost. Nakon 2. ciklusa hlađenja, dobiven je egzoterm koji predstavlja kristalizaciju rastaljenih kristala u ciklusu zagrijavanja. Kristalište (Tc) kompozita neznatno se mijenja s porastom udjela LJJ. FTIR analizom dobiven je infracrveni spektar s karakterističnim vrpcama funkcionalnih skupina za pojedine uzorke. Analizom pojedinih vrpci uzoraka vidljivo je da nisu dobivene apsorpcijske vrpce karakterističnih valnih brojeva koji bi ukazivali na postojanje LJJ tj. kalcijeva karbonata unutar kompozita.The desire and need to reduce environmental problems such as: environmental pollution, accumulation of garbage, exploitation of oil derivatives, excessive release of CO2, plastic in the seas and on land, were the reason for the preparation of new materials, which will have improved properties compared to individual components of which they consist of. The aim is to develop composites with a bio-base, preferably biodegradable, which would replace or at least partially replace already existing traditional materials. Polyethylene is one of the most well-known petroleum-based polymers, by mixing in eggshells, its mechanical properties could be improved. Various forms of this polymer are known with a wide range of applications. Samples of pure LLDPE, eggshell and LLDPE/LJJ biocomposite samples were examined by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) techniques. Using the DSC technique, it was determined that during the heating cycle, the addition of LJJ does not cause significant changes within the crystalline phase of LLDPE, that is, it does not affect the size of the crystals and their arrangement. After the 2nd cooling cycle, an exotherm was obtained, which represents the crystallization of the molten crystals in the heating cycle. The crystallinity (Tc) of the composite changes slightly with the increase in the proportion of LJJ. Infrared spectrum with characteristic bands of functional groups for individual samples was obtained by FTIR analysis. The analysis of individual bands of the samples shows that no absorption bands of characteristic wave numbers were obtained that would indicate the existence of LJJ, i.e. calcium carbonate within the composite
Influence of cellulose and associative thickeners on rheological properties of coatings
No full textReologija se definira kao znanost koja proučava deformacije i tok tvari pod utjecajem vanjskih sila. Željeno ponašanje premaza tijekom obrade, skladištenja, nanošenja te nakon nanošenja od velike je važnosti u industriji premaza, a upravo se reologija koristi kao metoda za istraživanje ponašanja svojstava tečenja i deformacije tijekom navedenih faza. Ispitivanja u ovom radu provedena su na premazima na bazi vode. Za premaze na bazi vode postoje različite vrste ugušćivača koje se razlikuju prema načinu ugušćivanja premaza. Postoje ugušćivači koji ugušćuju samo vodenu fazu, a postoje i asocijativni ugušćivači koji viskoznost sustava povećavaju interakcijama s drugim komponentama premaza. Cilj ovog rada bio je ispitati utjecaj celuloznih i asocijativnih ugušćivača na reološka svojstva premaza. Korišteni celulozni ugušćivači su ugušćivači na bazi karboksimetil celuloze, hidroksietil celuloze, hidroksietil metil celuloze te hidrofobno modificirane hidroksietil celuloze. Navedeni ugušćivači viskoznost premaza povećavaju ugušćivanjem vodene faze, osim hidrofobno modificirane hidroksietil celuloze, kod koje je prisutan i asocijativni mehanizam ugušćivanja. Od asocijativnih ugušćivača korišteni su poliuretanski ugušćivači ili hidrofobno modificirani etoksilirani uretani (eng. hydrophobically modified ethoxylated urethanes - HEUR) te asocijativni akrilni ugušćivači poznati kao hidrofobno modificirane emulzije koje bubre u alkalijama (eng. hydrophobically modified alkali-swellable emulsions - HASE). U svrhu ispitivanja utjecaja dodanih ugušćivača na svojstva premaza, raznim metodama određivana su toplinska, reološka, fizikalna, primjenska i mehanička svojstva, kao i površinske karakteristike premaza, iz kojih se na kraju utvrdio utjecaj dodatka različitih ugušćivača na reološka svojstva premaza.Rheology is defined as a science that studies the deformation and flow of matter under the influence of external forces. The desired behavior of the coating during processing, storage, application, and after application is of great importance in the coatings industry, and rheology is used as a method to study the flow behavior and deformations during the mentioned phases. The tests performed in this work were carried out on water-based coatings. There are different types of thickeners for water-based coatings, depending on the method used to thicken the coating. There are thickeners that only smother the water phase, and there are also associative thickeners that increase the viscosity of the system by interacting with other components of the coating. The aim of this work was to investigate the influence of cellulose and associative thickeners on the rheological properties of the coating. The cellulose thickeners used are thickeners based on carboxymethylcellulose, hydroxyethylcellulose, hydroxyethylmethylcellulose and hydrophobically modified hydroxyethylcellulose. The above thickeners increase the viscosity of the coating by thickening the aqueous phase, with the exception of hydrophobically modified hydroxyethyl cellulose, which also has an associative thickening mechanism. Polyurethane thickeners or hydrophobically modified ethoxylated urethanes (HEUR) and associative acrylic thickeners known as hydrophobically modified alkali swellable emulsions (HASE) were used as associative thickeners. In order to test the influence of the added thickeners on the properties of the coating, various methods were used to determine the thermal, rheological, physical, application, mechanical and surface properties of the coating, from which the influence of the addition of different thickeners on the rheological properties of the coating was determined
The effect of compatibilizers based on maleic anhydride on the morphology and mechanical properties of blends of polyethylene and waste polyamide powder
No full textU ovom radu ispitivan je utjecaj kompatibilizatora PE-g-MA na morfologiju i mehanička svojstva mješavina polietilena (PE) i otpadnog poliamidnog praha (PA). Uzorci su pripremljeni umješavanjem na gnjetilici i prešanjem na hidrauličkoj preši. Morfologija pripremljenih uzoraka nekompatibiliziranih i kompatibiliziranih mješavina ispitivana je pretražnim elektronskim mikroskopom. Mehanička i relaksacijska svojstva ispitivana su testom jednoosnog istezanja na mehaničkoj kidalici. Dodatkom PE-g-MA kompatibilizatora u mješavinu PE/PA ne dolazi do poboljšanja morfologije. Prisutna je fazna separacija bez dobre adhezije na međupovršini PE i PA faze. Također ne dolazi do značajnog poboljšanja mehaničkih svojstava kompatibiliziranih mješavina. Prekidno istezanje i prekidno naprezanje kod većine kompatibiliziranih sustava manje je u odnosnu na nekompatibilizirane mješavine. Usprkos tome, najbolje rezultate mehaničkog ispitivanja kompatibiliziranih mješavina pokazuju mješavine s udjelom PE od 20 i 80 % što ukazuje na uspješnost kompatibilizacije u određenoj mjeri.In this thesis, the influence of compatibilizer PE-g-MA on the morphology and mechanical properties of polyethylene (PE) and waste polyamide powder (PA) blends were investigated. Samples were prepared by mixing in a kneader and pressing with a hydraulic press. The morphology of non-compatibilized and compatibilized blends was examined using a scanning electron microscope. Mechanical and relaxation properties were tested using a uniaxial tensile test on a mechanical tear machine. The addition of the PE-g-MA compatibilizer to the PE/PA blend does not lead to an improvement in morphology. Phase separation is present without good adhesion at the interface between the PE and PA phases. Furthermore, there is no significant enhancement in the mechanical properties of the compatibilized blends. Elongation at break and breaking stress in most compatibilized systems are lower compared to non-compatibilized blends. Nevertheless, the best mechanical results of the compatibilized samples are shown by blends with a PE content of 20 and 80 %, indicating some degree of successful compatibilization
Biodegradable polymers in drug delivery
No full textRazvoj tehnologije doprinosi otkrivanju novih metoda, materijala, sustava za praćenje te sintezi novih spojeva. U novije doba, stavlja se naglasak na očuvanje okoliša smanjenjem kemijskog otpada i toksičnih nusprodukata. Razvoj raznih biorazgradivih polimernih materijala, ne samo da podržava ekologičnost nego se razvija paralelno s njom. Biorazgradivi polimeri su materijali koji se prirodno razgrađuju u okolišu, ali ne uvijek jednako brzo ili u jednakim uvjetima. Biorazgradnja se odvija uz pomoć mikroorganizama i enzima. Postoji više podjela biorazgradivih polimera, npr. prema kemijskom sastavu, primjeni, načinu dobivanja i preradi, ali najvažnija je podjela s obzirom na podrijetlo gdje razlikujemo prirodne (npr. škrob) i sintetske (npr. polilaktid) biorazgradive polimere. Njihova primjena je od sve većeg značaja zbog održive prirode i boljeg utjecaja na okoliš, ako se pravilno zbrinjavaju. Biorazgradivi polimerni materijali imaju raznovrsnu primjenu, npr. u medicinskoj industriji, farmaceutskoj industriji, poljoprivredi, tekstilnoj industriji, kod pakiranja ambalaža, itd. Ovaj rad se bazira na karakteristikama (struktura, dobivanje, svojstva) biorazgradivih polimera, njihovoj ulozi u modernom sustavu dostave lijekova te primjeni u izradi hidrogelova.The development of technology contributes to the discovery of new methods, materials, monitoring systems and the synthesis of new compounds. In recent times, emphasis has been placed on preserving the environment by reducing chemical waste and toxic
by-products. The development of various biopolymer materials not only supports ecology but also develops along with it. Biodegradable polymers are materials that break down naturally in the environment, but not always at the same speed or under the same conditions. Biodegradation takes place with the help of microorganisms and enzymes. There are several divisions of biopolymers, e.g., according to chemical composition, application, method of obtaining and processing, but the most important division is based on origin, where we distinguish between natural (e.g., starch) and synthetic (e.g., polylactide) biodegradable polymers. Their application is of increasing importance due to their sustainable nature and better impact on the environment, if they are properly disposed of. Biodegradable polymer materials have a variety of applications, for example, in the medical industry, pharmaceutical industry, agriculture, textile industry, packaging, etc. This work is based on the characteristics (structure, preparation, properties) of biodegradable polymers, their role in the modern drug delivery system and their application in the production of hydrogels
Synthesis, computational modeling and photochemistry of new 1,3-thiazolo-thienostilbenes
No full textInhibitori enzima kolinesteraza prepoznaju se kao jedan od glavnih izbora za smanjenje simptoma Alzheimerove bolesti, četvrte bolesti po redu koja uzrokuje smrt u razvijenim zemljama, zbog toga što uzrokuje da se razina neurotransmitera acetilkolina u kolinergičnim sinapsama povećava. U svrhu pronalaska još učinkovitijih inhibitora kolinesteraza, sintetizirani su u ovom radu novi derivati 1,3-tiazolo-tienostilbena 1-9 i njihovi fotoprodukti 10-16. Spojevi 1-5, 7 i 8 sintetizirani su Wittigovom reakcijom s tiofenskom fosfonijevom soli. Sinteza 1,3-tiazolo-tienostilbena 6 provela se amidacijom spoja 5 uz acetanhidrid, dok se spoj 9 sintetizirao Büchwald-Hartwigovim aminiranjem. Svi derivati 1-9 dobiveni su kao smjese cis- i trans- izomera. Na dobivenim spojevima 1-4 i 6-9 provedene su reakcije elektrociklizacije u fotokemijskom reaktoru Rayonet s 10 UV lampi na 300 nm, čime su se dobili novi derivati tienobenzo-tiazola 10-16. Sintetizirani su i novi derivati tienobenzo-triazola 23-25 nizom od tri reakcije. Svi dobiveni spojevi pročišćeni su kolonskom kromatografijom na silika-gelu. Čisti spojevi okarakterizirani su spektroskopskim metodama i poslani su na ispitivanje biološke aktivnosti. Koristile su se 1H i 13C NMR tehnike, UV-Vis spektroskopija, masena spektrometrija i HRMS analiza. Provelo se i računalno istraživanje kojim su proučavane geometrije i elektronske strukture dobivenih tiazola, te molekulski docking kojim su se identificirale interakcije između enzima i potencijalnog inhibitora s ciljem predviđanja jačine inhibicije.Inhibitors of enzymes cholinesterases are recognized as one of the main choices for reducing symptoms of Alzheimer's disease, the fourth leading cause of death in developed countries, because they cause an increase in the level of acetylcholine neurotransmitter in cholinergic synapses. In order to discover even more effective cholinesterase inhibitors, new derivatives of 1,3-thiazole-thienostilbenes 1-9 and their photoproducts 10-16 were synthesized in this study. Compounds 1-5, 7, and 8 were synthesized through the Wittig reaction with thiophene phosphonium salt. The synthesis of 1,3-thiazole-thienostilbene 6 was carried out by amidation of compound 5 with acetic anhydride, while compound 9 was synthesized by Büchwald-Hartwig amination. All derivatives 1-9 were gained as mixtures of cis- and trans-isomers. The obtained compounds 1-4 and 6-9 underwent electrocyclic reactions in a Rayonet photoreactor equipped with 10 UV lamps at 300 nm, resulting in new derivatives of thienobenzo-thiazoles 10-16. New derivatives of thienobenzo-triazoles 23-25 were also synthesized, through a series of three reactions. All obtained compounds were purified using column chromatography on silica gel. Pure compounds were characterized by spectroscopic methods and sent for biological activity testing. 1H and 13C NMR techniques, UV-Vis spectroscopy, mass spectrometry, and HRMS analyses were used. Computational research was also conducted to study the geometries and electronic structures of the obtained thiazoles, and molecular docking was performed to identify interactions between the enzyme and the potential inhibitor in order to predict the strength of the inhibition