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Aminopropylsilanetriol - theory and experiment
No full textGlavni cilj ovog rada je analiza aminopropilsilantriola teorijski, kvantno mehaničkim proračunima uz primjenu teorije funkcionala gustoće i eksperimentalno uz primjenu infracrvene spektroskopije s Fourierovom transformacijom (FTIR). Izračunom potencijalne energije u ovisnosti o torzijskom kutu SiCCC dobivene su dvije stabilne konformacije molekule, trans i gauche. Izračunata niža energija trans konformacije ukazuje da je to stabilnija konformacija od gauche konformacije. Za obje konformacije izračunate su optimalne geometrije i vibracijske frekvencije s infracrvenim intenzitetima. Izračuni su provedeni korištenjem programskog paketa Gaussian09 s B3LYP funkcionalom. Nakon što su dobiveni teorijski proračuni i eksperimentalni rezultati, napravljena je vibracijska i konformacijska analiza te su uspoređeni dobiveni infracrveni spektri. Aminopropilsilantriol je spoj koji zbog svoje sposobnosti povezivanja organskih i anorganskih spojeva u današnje vrijeme nalazi sve širu industrijsku primjenu. Međutim, da bi se njegova primjena još više proširila, potrebno je detaljno poznavati njegovu strukturu, veze i energije vibracija. Aminopropilsilantriol je stabilan u vodenoj otopini pa se teško eksperimentalno mogu dobiti podaci o strukturi same molekule. Tu su od velike koristi teorijski proračuni strukture i drugih parametara. U ovom radu je napravljen izračun geometrije stabilnih konformacija i proračun vibracijskih frekvencija. Usporedba vibracijskih frekvencija dvaju konformacija ukazuje na većinski slične spektre s glavnom razlikom u području istezanja CC, CN i SiC veza što je posljedica različitog diedarskog kuta navedenih struktura. Usporedba geometrijskih parametara ukazuje na sličnost struktura dvaju konformacija s glavnom razlikom u diedarskom kutu SiCCC.The main objective of this master thesis is to analyze aminopropylsilanetriol theoretically by means of quantum mechanical calculations using density functional theory and experimentally with the application of Fourier transform infrared spectroscopy (FTIR).
By calculating the potential energy depending on the torsion angle of SiCCC, two stable conformations of the molecule, trans and gauche, were obtained. The calculated lower energy of the trans conformation indicates that it is more stable than the gauche conformation. For both conformations, the optimal geometries and vibrational frequencies with infrared intensities were calculated. The calculations were performed using the Gaussian09 software package with the B3LYP functional. After obtaining the theoretical calculations and experimental results, a vibrational and conformational analysis was conducted, and the resulting infrared spectra were compared. Aminopropylsilanetriol is a compound that is increasingly being used in various industrial applications due to its ability to connect organic and inorganic compounds. However, in order to expand its application even more, it is necessary to know in detail its structure, bonds and vibration energies. Aminopropylsilanetriol is stable in aqueous solution, making it difficult to experimentally obtain data on the structure of the molecule itself. Theoretical calculations of the structure and other parameters are therefore very useful. In this study, the geometry of stable conformations and vibrational frequencies were calculated. A comparison of the vibrational frequencies of the two conformations indicates mostly similar spectra with the main difference in the area of stretching of CC, CN and SiC bonds, which is a consequence of the different dihedral angle of the mentioned atoms. It has been shown that there are no significant differences between the observed conformations, but certain results indicate the stability of the trans conformation
Thermal transformations of novel styryl-derivatives of thiophene in acidic medium
No full textCilj ovog rada je sintetizirati nove heterocikličke stirilne sustave koji će se podvrgnuti termičkim ispitivanjima kako bi se eksperimentalno potvrdile kvantno-kemijske pretpostavke o reaktivnosti određenih spojeva. U prvom dijelu istraživanja sintetiziran je derivat tiofena s nitro-skupinom kao supstituentom, dok je u drugom dijelu sintetiziran derivat tiofena s dvije metilne skupine kao supstituentima. Sinteze novih produkata provedene su Wittigovom reakcijom i Vilsmeierovim formiliranjem za pripravu aldehida u drugoj sintezi. Dobiveni produkti su analizirani spektroskopskim metodama.The aim of this work is to conduct the synthesis and thermal transformation of new heterocyclic styryl systems in order to confirm quantum-chemical assumptions about the reaction outcome. In the first part of the research, a thiophene derivative with a nitro group as a substituent was synthesized, while in the second part, a thiophene derivative with two methyl groups as substituents was synthesized. Syntheses of new products were carried out by Wittig reaction and Vilsmeier formylation for the preparation of aldehydes in the second synthesis. The obtained products were analyzed by spectroscopic methods
Protection of bronze patina with polymer nanocoatings
No full textUmjetnička djela i kulturna baština od bronce, izloženi su svakodnevnim onečišćenjima prisutnim u otvorenoj ili zatvorenoj atmosferi. Stoga su podložni korozijskim procesima koji mogu dovesti do promjena u njihovom izgledu i stabilnosti te do propadanja materijala koji zatim uzrokuju materijalne troškove popravka ili zamjene. Takvi objekti su često prekriveni patinom, koja ima estetsku i/ili povijesnu vrijednost. Patina na brončanim skulpturama također štiti osnovni metal samog umjetničkog predmeta. Cilj ovog rada bio je ispitati mogućnost zaštite bronce i njezine patine od korozije uzrokovane kiselim kišama, primjenom neumreženih i umreženih samoorganizirajućih monoslojeva behenske kiseline. Ispitivanja su provedena u otopini koja simulira kiselu kišu pri pH 5. Behenska kiselina, C21H43COOH, također poznata kao dokozanska kiselina pripada dugolančanim zasićenim masnim kiselinama. Uzorci su zračeni na panoramskom izvoru 60Co gama zračenja s ciljem induciranja umrežavanja samoorganiziranog sloja behenske kiseline. Stabilnost dobivenih prevlaka u simuliranoj kiseloj kiši proučavana je elektrokemijskim metodama (metoda Tafelove ekstrapolacije i elektrokemijska impedancijska spektroskopija), dok su površine karakterizirane pretražnim elektronskim miskroskopom (SEM), Raman spektroskopijom i metodom mjerenja kontaktnog kuta. Dobiveni rezultati pokazali su da najveću otpornost na koroziju ima uzorak čiste bronce prekriven umreženom prevlakom. Kod uzoraka zelene patine prekrivene PNC-om vidljiva je najbolja kratkoročna zaštita od korozije. Nakon zračenja u UV komori primijećeno je da kod uzoraka prekivenima neozračenom behenskom kiselinom dolazi do degradacije prevlake dok uzorci prekriveni ozračenim filmom ostaju postojani.Works of art and cultural heritage made of bronze are exposed to everyday pollution present in an open or closed atmosphere. Therefore, they are subject to corrosion processes that can lead to changes in their appearance and stability as well as material deterioration, resulting in material costs for repair or replacement. Such objects are often covered with a patina that has aesthetic and/or historical value. The patina on bronze sculptures protects the base metal of the art object itself. The aim of this work was to investigate the possibility of protecting bronze and its patinat from corrosion caused by acid rain by self-assembled molecular layers of behenic acid. The tests were carried out in a solution simulating acid rain at pH 5. Behenic acid, C21H43COOH, also known as docosanoic acid, belongs to the long-chain saturated fatty acids. The samples were irradiated at a panoramic 60Co gamma irradiation source with the aim of inducing crosslinking of behenic acid self-assembled molecular layers. The stability of the obtained coatings in simulated acid rain were studied by electrochemical methods (Tafel extrapolation method and electrochemical impedance spectroscopy ), while the surfaces were characterization by Scanning electron microscope (SEM), Raman spectroscopy and contact angle measurements. The obtained results showed that the pure bronze sample covered with a cross-linked coating has the highest resistance to corrosion. The green patina samples covered with PNC show the best short-term corrosion protection. After irradiation in the UV chamber, it was observed that the coating was degraded in the samples covered with non-irradiated behenic acid, while the samples covered with the irradiated film remained stable
Binary green blends of corn thermoplastic starch (TPS) with poly(3-hydroxybutyrate-co-3-hydroxyvalerate)
No full textStalni porast sintetske plastike u okolišu stvara hitnu potrebu za novim, biorazgradljivim materijalima. Polihidroksialkanoati (PHA) su se nedavno istaknuli kao obećavajući kandidati, posebno poli(3-hidroksibutirat-ko-3-hidroksivalerat) (PHBV). PHBV je biorazgradljivi polimer s dobrim mehaničkim svojstvima i velikim potencijalom za zamjenu tradicionalne plastike iz fosilnih goriva. Međutim, njegova visoka tržišna cijena ograničava širu primjenu. Ovaj rad se fokusira na pripremu biomaterijala na bazi PHBV-a i termoplastičnog škroba (TPS). TPS je pripremljen metodom lijevanja uz korištenje glicerola kao plastifikatora. Mješavine TPS-a i PHBV-a pripremljene su u Brabender gnjetilici, a potom su analizirana njihova, morfološka, toplinska,mehanička i barijerna svojstva. Diferencijalna pretražna kalorimetrija (DSC) korištena je za određivanje faznih prijelaza, dok je termogravimetrijska analiza (TGA) provedena radi uvida u toplinsku stabilnost materijala. Osnovna mehanička svojstva, prekidno naprezanje i prekidno istezanje, ispitana su na mehaničkoj kidalici. Uvid u morfologiju proveden je pretražnim elektronskim mikroskopom (SEM), dok je propusnost vodene pare određena Herfeldovom metodom.. DSC analiza ukazuje na djelomičnu mješljivost TPS/PHBV polimernih mješavina, što je vidljivo iz pomaka temperature staklišta pojedine komponente. TGA analizom potvrđeno je da se sve TPS/PHBV polimerne mješavine razgrađuju u dva stupnja: prvi stupanj odnosi se na razgradnju toplinski manje stabilnog PHBV-a, dok drugi stupanj obuhvaća razgradnju toplinski stabilnijeg TPS-a. Mehanička ispitivanja pokazala su da se vrijednosti prekidne čvrstoće TPS/PHBV polimernih mješavina nalaze između vrijednosti čistih komponenti TPS-a i PHBV-a. Vrijednosti propusnosti vodene pare TPS/PHBV polimernih mješavina također su smještene između vrijednosti propusnosti vodene pare izmjerenih za čiste komponente. SEM analizom dodatno je potvrđena djelomična mješljivost TPS/PHBV polimernih mješavina.The continuous increase of synthetic plastics in the environment creates an urgent need for new, biodegradable materials. Polyhydroxyalkanoates (PHA) have recently emerged as promising candidates, especially poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). PHBV is a biodegradable polymer with good mechanical properties and great potential to replace traditional fossil fuel-based plastics. However, its high market price limits its wider application. This work focuses on the preparation of biomaterials based on PHBV and thermoplastic starch (TPS). TPS was prepared using the casting method with glycerol as a plasticizer. TPS and PHBV blends were prepared in a Brabender kneader, and their morphological, thermal, mechanical, and barrier properties were analyzed. Differential scanning calorimetry (DSC) was used to determine phase transitions, while thermogravimetric analysis (TGA) was conducted to gain insight into the thermal stability of the materials. Basic mechanical properties, tensile strength, and elongation at break were tested using a mechanical testing machine. Morphology was examined using a scanning electron microscope (SEM), and water vapor permeability was determined using the Herfeld method. DSC analysis indicates partial miscibility of TPS/PHBV polymer blends, as evidenced by the shift in the glass transition temperature of each component. TGA analysis confirmed that all TPS/PHBV polymer blends decompose in two stages: the first stage corresponds to the decomposition of the thermally less stable PHBV, while the second stage involves the decomposition of the thermally more stable TPS. Mechanical tests showed that the tensile strength values of TPS/PHBV polymer blends fall between those of the pure components TPS and PHBV. The water vapor permeability values of TPS/PHBV polymer blends also fall between the water vapor permeability values measured for the pure components.
SEM analysis further confirmed the partial miscibility of TPS/PHBV polymer blends
Implementation of photochemical reactions using 3D-printed reactors
No full textAditivna tehnologija (engl. additive manufacturing, AM) predstavlja skup postupaka koji omogućuju izradu predmeta, na temelju računalnog 3D-modela, nanošenjem čestica u tankim slojevima, sloj po sloj. Tehnologije aditivne proizvodnje korištene u ovom radu su proizvodnja rastaljenim filamentom (FFF), stereolitografija (SLA) i digitalna obrada svjetlom (DLP). Prvi cilj ovog rada bio je, tehnologijama FFF, SLA i DLP na 3D-pisačima, izraditi ispitne pločice od transparentnih materijala kako bi se odredio najprikladniji materijal za
3D-ispis reaktora u kojima će se provoditi fotokemijske reakcije u trajanju od 2 sata. Za izradu modela ispitnih pločica korišten je program za računalno potpomognuti dizajn (engl. computer aided design, CAD) Fusion 360, nakon čega je uslijedio 3D-ispis istih. FFF tehnologijom izrađeni su modeli pločica od polipropilena (PP) i polietilen tereftalata obogaćenog glikolom (PETG), SLA tehnologijom oni su izrađeni od poliakrilata, dok su DLP tehnologijom izrađeni od smjese poliakrilata i epoksida. Uz to, materijali korišteni u SLA i DLP tehnologiji aditivne proizvodnje podvrgnuti su i post-obradi, odnosno procesu naknadnog očvršćivanja u trajanju od 5 i 15 minuta. Svojstva polimera korištenih za izradu pločica ispitana su testom bubrenja u otapalu acetonitrilu. Rezultati ukazuju na to da je stupanj bubrenja uzorka veći, ukoliko je vrijeme naknadnog očvršćivanja manje. Nakon provedenog ispitivanja i s obzirom na stupanj bubrenja, zaključeno je da je smola High Temp pogodna za ispis reaktora jer ima najmanji stupanj bubrenja nakon 4 sata, a iznosi 3,2 %. Osim toga, cilj rada bio je i provoditi fotokemijske reakcije u reaktoru Luzchem CCP-ICH2 u trajanju od
2 sata i pri valnoj duljini 313 nm. Za provođenje fotokemijskih reakcija korišteni su reaktori sa statičkim miješalicama i reaktori bez statičkih miješalica. Za izradu reaktora korišten je CAD program Fusion 360, nakon čega je uslijedio 3D-ispis istih. Reaktori su zatim podvrgnuti post-obradi u trajanju od 5 minuta. Fotokemijske reakcije provodile su se kako bismo vidjeli postoji li razlika u dobivenim produktima tijekom korištenja reaktora sa statičkim miješalicama i bez statičkih miješalica, te kako bismo vidjeli je li njihovim korištenjem postignuta bolja konverzija u odnosu na šaržnu fotokemijsku sintezu. Za utvrđivanje prisutnosti fotoprodukata nakon provedenih reakcija korištene su tankoslojna kromatografija i tekućinska kromatografija vrlo visoke učinkovitosti. Rezultati dobiveni provođenjem fotokemijskih reakcija ukazuju da je najveće pseudoiskorištenje reakcije postignuto nakon 2 sata provođenja iste u reaktoru s pregradama, odnosno za uzorak 3-preg-2h(I2) i iznosi 21,15 %, dok je najmanje pseudoiskorištenje nakon 2 sata provođenja reakcije postignuto u praznom reaktoru, odnosno za uzorak 3-praz-2h(I2) i iznosi 6,69 %. Uz to, provođenjem fotokemijskih reakcija kod uzoraka 3-praz-1h(I2), 3-praz-2h(I2), 3-stup-1h(I2) i 3-stup-2h(I2), ciljani produkt 4 nastaje u relativno niskom iskorištenju, dok kod uzoraka 3-senz-e-1h i 3-senz-e-2h nastaje nešto više sporednih produkata u odnosu na glavni produkt. Ovi rezultati upućuju na činjenicu da je miješanje vjerojatno najintenzivnije u reaktoru s pregradama. Osim toga, veća iskorištenja u slučaju reaktora smanjenog volumena upućuju na činjenicu da tanji sloj kroz koji svjetlost prolazi tijekom reakcije ima značajan utjecaj na iskorištenje, ali isto tako da i materijal kroz koji svjetlost prolazi, što je kod ovog reaktora polimer, može imati značajan utjecaj na iskorištenje.Additive manufacturing (AM) represents a set of processes that enable the creation of objects based on a computer 3D model by applying particles in thin layers, layer by layer. The additive manufacturing technologies used in this work are fused filament fabrication (FFF), stereolithography (SLA), and digital light processing (DLP). The first goal of this work was to use FFF, SLA, and DLP technologies on 3D printers to create test plates from transparent materials to determine the most suitable material for 3D printing of reactors in which photochemical reactions would be conducted for 2 hours. The computer-aided design (CAD) software Fusion 360 was used to create the test plate models, followed by 3D printing of the same. Using FFF technology, models of plates were made from polypropylene (PP) and polyethylene terephthalate glycol (PETG), while SLA technology produced models from polyacrylate, and DLP technology produced models from a mixture of polyacrylate and epoxy. Additionally, the materials used in SLA and DLP additive manufacturing technologies undergo post-processing, or a subsequent curing process lasting 5 and 15 minutes. Properties of the polymers used to create the plates were tested using a swelling test in the acetonitrile solvent. The results indicate that the degree of swelling of the sample is greater if the post-curing time is shorter. After conducting the test and considering the degree of swelling, it was concluded that the High Temp resin is suitable for printing reactors because it has the lowest swelling degree after 4 hours, amounting to 3.2 %. Additionally, the aim of this work was to conduct photochemical reactions in the Luzchem CCP-ICH2 reactor for a duration of 2 hours at a wavelength of 313 nm. For conducting photochemical reactions, reactors with static mixers and reactors without static mixers were used. The CAD program Fusion 360 was used to create the reactors, followed by 3D printing of the same. The reactors were then subjected to post-processing for 5 minutes. The photochemical reactions were conducted to see if there is a difference in the obtained products when using reactors with static mixers versus without static mixers, and to see if better conversion is achieved compared to batch photochemical synthesis. Thin-layer chromatography and ultra-high-performance liquid chromatography were used to determine the presence of photoproducts after the reactions. The results obtained from conducting photochemical reactions indicate that the highest reaction pseudo-yield of the reaction was achieved after 2 hours of conducting it ina reactor with partitions, specifically for the sample 3-preg-2h(I2) and amounts to 21,15 %, while the lowest pseudo-yield was achieved after 2 hours of conducting the reaction in an empty reactor, specifically for the sample 3-praz-2h(I2) and amounts to only 6.69 %. Additionally, conducting photochemical reactions for samples 3-praz-1h(I2),
3-praz-2h(I2), 3-stup-1h(I2) and 3-stup-2h(I2), the target product 4 is produced in relatively low yields, whereas for samples 3-senz-e-1h and 3-senz-e-2h somewhat more by-products are formed in relation to the main product. These results indicate that mixing is probably most intense in the reactor with partitions. Furthermore, highter yields in the case of a reduced volume reactor indicate that a thiner layer through which light passes during the reaction has a significant impact of the yield, but aldso that the material through which light passes, which is a polymer in this reactor, cas also have a significant impact of the yield
Preparation of composite porous materials based on bioactive glass and biodegradable polymer
No full textKompozitni porozni materijali kombiniraju različite komponente kako bi se postigla poboljšana svojstva koja nadilaze mogućnosti pojedinačnih materijala. Posebno zanimanje izazivaju kompoziti koji sadrže bioaktivno staklo i biorazgradljive polimere, zbog sposobnosti da simultano osiguraju strukturnu podršku, stimuliraju regeneraciju tkiva i postupno se razgrađuju unutar organizma. Bioaktivno staklo zbog svoje biokompatibilnosti i sposobnosti interakcije s biološkim tkivom ima široku primjenu u regenerativnoj medicini, posebice u obliku trodimenzionalnih nosača za tkivno inženjerstvo. Cilj ovog diplomskog rada je priprema kompozitnih trodimenzionalnih nosača na temelju visokoporozne matrice koja je sačinjena od biostakla te kompozitnih sfera na temelju kitozana. Takvi nosači pripravljeni su metodom repliciranja žrtvovanog predloška (engl. foam replica method). Osnovni zadatak bio je pronaći odgovarajući postupak i najbolje parametre kako bi se sfere uspješno sljepile na staklenu trodimenzionalnu matricu. Prethodnim istraživanjima potvrđeni su optimalni parametri sinteze mikrosfera metodom elektroštrcanja. Prilikom impregnacije sfera na nosač pripremaju se suspenzije 5%, odnosno 10% mase sfera na volumen otapala. Za ljepljenje sfera za nosač pripremljena je otopina natrijevog alginata od 0,5, 1 i 2 mas./vol. %. Uspješnost procesa procijenjena je na temelju gubitka mase nakon žarenja i SEM analizom. Potvrđena je stabilnost nosača od bioaktivnog stakla. Njegova je struktura složena i visokoporozna, hrapave površine što pomaže pri integraciji s biološkim tkivom. Rezultati su pokazali da uzorak BG-1ALG sadrži najdeblju polimernu prevlaku, što ukazuje na optimalnu koncentraciju alginata za postizanje najbolje adhezije mikrosfera. Zaključeno je da je uzorak BG-1ALG-10SF najpovoljniji, kombinirajući adekvatnu količinu sfera i visokoporoznu strukturu, što ga čini pogodnim za primjenu u medicini.Composite porous materials combine different components in order to achieve enhanced properties that exceed the capabilities of individual materials. Composites containing bioactive glass and biodegradable polymers are of particular interest due to their ability to simultaneously provide structural support, stimulate tissue regeneration and gradually degrade within the body. Because of its biocompatibility and ability to interact with biological tissue, bioactive glass is widely used in regenerative medicine, especially in the form of a three-dimensional scaffold for tissue engineering. The objective of this thesis is to prepare composite three-dimensional scaffolds using a highly porous matrix composed of bioglass and chitosan-based spheres. Such scaffolds are prepared using the foam replica method. The primary task was to find suitable procedures and optimal parameters to successfully stick the spheres onto the three-dimensional glass matrix. Previous research has confirmed the optimal parameters for the synthesis of microspheres using the electrospraying method. To impregnate the spheres on to the scaffold, suspensions with 5% or 10% of the sphere mass per volume of solvent are prepared. A sodium alginate solution of 0.5, 1 and 2 w/v % was prepared for glueing the spheres to the scaffold. The effectiveness of the process was evaluated by the loss of mass after annealing and through SEM analysis. The stability of the bioactive glass scaffold was confirmed. Its structure is complex and highly porous, with a rough surface that facilitates integration with biological tissue. The results showed that sample BG-1ALG contains the thickest polymer coating, which indicates the optimal concentration of alginate to achieve the best adhesion of microspheres. It was concluded that the sample BG-1ALG-10SF is the most effective, combining an adequate amount of spheres and a highly porous structure, which makes it suitable for medical applications
Japan-Croatia Joint Symposium on Chemical Engineering & Plasma Agriculture for Young Scientists Global Networking (JC-JSChEPA) : knjiga sažetaka
No full textBook of abstracts of the Japan-Croatia Joint Symposium on Chemical Engineering & Plasma Agriculture for Young Scientists Global Networking (JC-JSChEPA). JC-JSChEPA is organized to give a unique opportunity for students and young scientists to connect on an international scale with the keyword of "Chemical engineering".Knjiga sažetaka s međunarodnog simpozija pod nazivom "Japan-Croatia Joint Symposium on Chemical Engineering & Plasma Agriculture for Young Scientists Global Networking (JC-JSChEPA)" koji je organiziran u svrhu povezivanja studenata i mladih znanstvenika na međunarodnoj razini u području kemijskog inženjerstva
Fabrication of flexible and conductive films based on graft copolymer PEDOT-g-PCL by inkjet technique
No full textInovacije u industrijskoj automatizaciji, informacijskoj i komunikacijskoj tehnologiji, obnovljivim izvorima energije te područjima razvoja senzora, već neko vrijeme otvaraju put za pametne uređaje koji imaju sposobnost prikupljanja i prijenosa informacija na Internet. Uzevši u obzir sve veću potražnju za velikim, ali cjenovno pristupačnim oblicima takvih uređaja, tiskana elektronika privlači pažnju kako industrije tako i akademske zajednice. Inkjet ispis nudi jednostavan način za proizvodnju sljedeće generacije elektroničkih uređaja, kombinirajući slobodu dizajna aditivnih proizvodnih tehnologija s prilagodljivim svojstvima funkcionalnih materijala te mogućnostima njihove integracije u nove strukture. Kao takvi, ističu se elektrovodljivi polimeri zbog raznolikih svojstava otpornosti na koroziju, električne vodljivosti te niske gustoće. Jedan od glavnih predstavnika elektrovodljivih polimera je
poli(3,4-etilendioksitiofen) (PEDOT) upravo zbog svoje biokompatibilnosti, kemijske stabilnosti te električne vodljivosti zahvaljujući kojoj se svrstava u rang poluvodiča.
Unatoč odličnim svojstvima, prisutan je nedostatak rastezljivih i samozacjeljujućih svojstava PEDOT-a, koji onemogućuju primjenu u nosivoj elektronici u kontaktu s ljudskom kožom. Stoga, cilj rada bio je sintetizirati graft kopolimer PEDOT-g-HEMA-PCL s dvije različite molekulske mase HEMA-PCL. Sinteza se provodila u četiri koraka, prvi je sinteza monomera 2-(tiofen-3-il) etil 2-bromo-2-metilpropanoat (ThBr), drugi sinteza makroinicijatora
PEDOT-Br-a u dva omjera, 2:1 i 5:1. U trećem koraku provodila se sinteza graft kopolimera PEDOT-g-HEMA-PCL, s različitim molekulskim masama HEMA-PCL-a, radikalskom polimerizacijom uz prijenos atoma (ATRP). Dobiveni uzorci okarakterizirani su nuklearnom magnetskom rezonancijom (NMR), infracrvenom spektroskopijom s Fourieriovom transformacijom (FTIR), termogravimetrijskom analizom (TGA) i diferencijalnom pretražnom kalorimetrijom (DSC). Također, pripremljene su tinte za inkjet ispis na poliuretansku (PU) podlogu, te su ispitana svojstva elektrovodljivosti metodom sondi s 4 točke, svojstvo istezljivosti te adhezivnosti.Innovations in industrial automation, information and communication technology, renewable energy sources, and sensor development have been paving the way for smart devices capable of collecting and transmitting information to the Internet for some time now. Given the increasing demand for large yet cost-effective forms of such devices, printed electronics has been attracting the attention of both industry and academia. Inkjet printing offers a straightforward method for manufacturing the next generation of electronic devices by combining the design freedom of additive manufacturing technologies with the tunable properties of functional materials and their potential integration into new structures. Conductive polymers stand out in this context due to their diverse properties, such as corrosion resistance, electrical conductivity, and low density. One of the main representatives of conductive polymers is poly(3,4-ethylenedioxythiophene) (PEDOT), known for its biocompatibility, chemical stability, and electrical conductivity, which classifies it as a semiconductor. Despite its excellent properties, PEDOT lacks stretchable and self-healing characteristics, limiting its application in wearable electronics that come into contact with human skin. Therefore, the aim of this work is to synthesize the graft copolymer
PEDOT-g-HEMA-PCL with two different molecular weights of HEMA-PCL.
The synthesis was conducted in four steps: the first step was the synthesis of the monomer 2-(thiophen-3-yl) ethyl 2-bromo-2-methylpropanoate (ThBr), followed by the synthesis of the macroinitiator PEDOT-Br in two ratios, 2:1 and 5:1. The third step involved the synthesis of the graft copolymers PEDOT-g-HEMA-PCL, consisting of two HEMA-PCL with different molar masses, via atom transfer radical polymerization (ATRP). The obtained samples were characterized by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Additionally, inks were prepared for inkjet printing on a polyurethane (PU) substrate, their electrical conductivity was tested using the four-point probe method, their stretchability and adhesion properties were also tested
Structure and properties of polylactide/diatom composites
No full textKompoziti su materijali sastavljeni od najmanje dviju komponenata različitih svojstava koji zajedno tvore novi materijal s poboljšanim svojstvima u odnosu na pojedinačne komponente. Polimerni kompozit sastoji se od kontinuirane faze, polimerne matrice u kojoj je raspodijeljena, dispergirana faza, punilo. U ovom radu kao matrica korišten je polimer polilaktid (PLA) a kao dispergirana faza korišteno je punilo dijatom (D). Polilaktid (PLA) je termoplastičan biorazgradivi polimer koji se sve više istražuje kao alternativa tradicionalnim plastikama iz fosilnih goriva, poput polietilena i polipropilena, dok je dijatom prirodno anorgansko punilo, amorfna silika (SiO2) koja potječe od sićušnih algi kremenjašica.
Cilj ovog rada je ispitati utjecaj dodatka različitog udjela dijatoma na svojstva polilaktida. Ispitivanja su provedena na uzorcima pripremljenim u talini u Brabender gnjetilici i prešani na hidrauličkoj preši. Mehanička svojstva kompozita ispitana su rasteznim ispitivanjem, dok su toplinska svojstva analizirana diferencijalnom pretražnom kalorimetrijom (DSC) i termogravimetrijskom analizom (TGA). Slobodna površinska energija određena je s mjerenjem kontaktnog kuta metodom položene kapi.Composite materials are materials that consist of at least two components with different properties and form a new material with improved properties compared to the individual components. A polymer composite consists of a continuous phase and a polymer matrix in which a dispersed phase, a filler, is distributed. In this work, the polymer polylactide (PLA) was used as the matrix and the diatom filler (D) as the dispersed phase. Polylactide (PLA) is a thermoplastic, biodegradable polymer that is increasingly being explored as an alternative to conventional fossil fuel-derived plastics such as polyethylene and polypropylene, while diatomaceous earth is a natural inorganic filler, amorphous silica (SiO2), derived from tiny diatoms. The aim of this work is to investigate the influence of the addition of different proportions of diatoms on the properties of polylactide. The tests were carried out on samples produced in a melt in a Brabender kneader and pressed on a hydraulic press.
The mechanical properties of the composite were tested by tensile tests, while the thermal properties were analyzed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The surface free energy was determined by measuring the contact angle using the placed drop method
The study of photocatalytic activity of zirconium doped cerium(IV) oxide
No full textCerijev(IV) oksid poznat je po vrlo dobroj katalitičkoj i fotokatalitičkoj aktivnosti u različitim reakcijskim sustavima, a posebice onima kojima je cilj uklanjanje štetnih tvari iz okoliša. Štetni utjecaj organskih boja na vodeni ekosustav i ljudsko zdravlje, dobro je poznat ekološki problem, a jedna od najučinkovitijih metoda za njihovo uklanjanje iz okoliša je heterogena fotokataliza. Stoga je u ovom radu ispitivana je fotokatalitička aktivnost uzoraka cerijeva (IV) oksida dopiranog s različitim količinama cirkonija (0, 10, 20 i 30 mol%) u procesu razgradnje metilenskog plavila (MB) i rodamina B (RhB), dvije često korištene industrijske boje koje su toksične u prekomjernim koncentracijama i imaju tendenciju akumulacije u okolišu. Uzorci su sintetizirani sintezom izgaranja, koja omogućuje brzu pripravu poroznih materijala uz nisku cijenu prekursora i manju potrošnju energije. Pripremljeni fotokatalizatori su karakterizirani pomoću rendgenske difrakcijske analize (XRD), Fourierove transformacijske infracrvene spektroskopije (FTIR), skenirajuće elektronske mikroskopije (SEM), energijski razlučujuće rendgenske spektroskopije (EDS) i UV-Vis difuzne refleksijske spektroskopije (UV-Vis DRS). Fotokatalitička aktivnost materijala testirana je u procesu razgradnje rodamina B (RhB) i metilenskog plavila (MB) (c₀ = 10 mg L⁻¹) pod UV-A svjetlom. Uzorak cerijeva oksida dopiran s 30 mol. % cirkonija pokazao je najvišu fotokatalitičku aktivnost u procesu fotokatalitičke razgradnje navedenih boja.Cerium(IV) oxide is known for its very good catalytic and photocatalytic activity in various reaction systems, especially those whose goal is to remove harmful substances from the environment. The harmful impact of organic dyes on the aquatic ecosystem and human health is a well-known environmental problem, and one of the most effective methods for their removal from the environment is heterogeneous photocatalysis. Therefore, in this work, the photocatalytic activity of samples of cerium (IV) oxide doped with different amounts of zirconium (0, 10, 20 and 30 mol%) was investigated in the process of decomposition of methylene blue (MB) and Rhodamine B (RhB), two frequently used industrial colors that are toxic in excessive concentrations and tend to accumulate in the environment. The samples were synthesized by combustion synthesis, which enables rapid preparation of porous materials with low precursor cost and lower energy consumption. The prepared photocatalysts were characterized using X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS).
The photocatalytic activity of the prepared materials was tested in the process of degradation of Rhodamine B (RhB) and methylene blue (MB) (c₀ = 10 mg L⁻¹) under UV-A light. Cerium oxide sample doped with 30 mol. % of zirconium showed the highest photocatalytic activity in the process of photocatalytic decomposition of the aforementioned dyes