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Dear colleagues, we are extremely honoured to present to you the Proceedings of the international conference 19th Ružička Days, which was successfully held on September 21–23, 2022, in Vukovar, Croatia, in the hometown town of our famous Croatian scientist and first Nobel laureate, professor Leopold (Lavoslav) Ružička. The main goals of the Conference were to promote excellence, originality and innovation of interdisciplinary scientific research as well as the practical application of the obtained results through collaboration with industry, emphasizing thus the recognizable slogan of the Ružička Days conference: "Today Science – Tomorrow Industry". In addition, the Conference gave the opportunity for meetings, exchanging the ideas, opinions, experiences and cooperation among participants from different working surroundings. It is also important to point out that since 2008, within the international conference Ružička Days, Meeting of Young Chemists has also been held, where high school students, with the help of their mentors, present papers in the field of chemistry, with the aim to direct students and young people to the technical and natural sciences, especially chemistry. In its seventh issue (2011, 2013, 2015, 2017, 2019, 2021) the Proceedings publishes scientific and professional full papers of high quality in the following sections: Chemical analysis and synthesis (10), Chemical and biochemical engineering (3), Food technology and biotechnology (4), Chemistry in agriculture and forestry (1), Environmental protection (9) and 8th Meeting of Young Chemists (3). Full-length papers were subjected to an international review procedure done by eminent experts from the corresponding fields, to whom we express our gratitude, but they were not subjected to linguistic proofreading. On behalf of the Scientific and Organizing Committee of the 19th Ružička Days we cordially thank all the authors, reviewers, participants, lecturers, organizers, especially the international organizers EuCheMS and EHEDG, auspices and sponsors, and all the others who, in any way, supported the Conference and contributed to the preparation of the Proceedings, especially to our highly skilled and committed associates, who have put a lot of effort in the preparation of these Proceedings. At the very end, special thanks to our young, future scientists and their mentors who are faithful participants of the Meeting of Young Chemists of the Ružička Days conference. Enjoy the extremely interesting scientific and professional papers contained in these Proceedings, until the next 20th jubilee of Ružička Days in 2024! We are looking forward to meeting you again in Vukovar! Yours sincerely, Chief Editors Jurislav Babić Vesna Ocelić Bulatović Dajana Kučić Grgić

Ispitan je utjecaj različitih oksidnih nosača željezovih nanočestica na krajnja svojstva kompozitnog materijala sa polilaktidnom matricom (PLA). Nanočestice željeza sintetizirane su prema literaturi [1] te su modificirana koristeći SiO2 ili TiO2 kao njihove nosače. Različite kombinacije punila korištene su za pripremu PLA kompozita. Prvo su pripremljeni kompoziti sa 0, 5 % mas punila čistih oksida. Naknadno, u takvu početnu smjesu dodavano je 0, 5 % mas hibridnih punila (punila: silicijev oksid/željezove nanočestice -HSI, titanov oksid/željezove nanočestice -HTI). Također, priređeni su kompoziti samo sa 0, 5 % mas hibridnog punila. Pripremljenim kompozitnim materijalima ispitana su različita primjenska svojstva. Toplinska stabilnost praćena je uz pomoć termogravimetrijske analize (TGA), toplinska provodnost ispitana je metodom „vrućeg mosta“, a volumna električna otpornost pomoću uređaja konstruiranog prema ASTM D257 normi. Također je provjeren utjecaj pripremljenih čestica i na mehanička svojstva kompozitnog materijala mehaničkim vlačnim ispitivanjem. Rezultati pokazuju kako korištenje druge vrste nosača za željezove nanočestice može imati različit utjecaj na primjenska svojstva ; primjerice dodatak TiO2 kao nosača uvelike narušava mehanička svojstva kompozita za razliku od SiO2, odnosno SiO2 povećava toplinsku provodnost, a dodatak TiO2 nema značajan utjecaj na nju.

Antibiotics have become a great environmental issue of modern world. Their concentrations are gradually rising in wastewater and ground water where they are imposing a risk for aquatic and terrestrial organisms. Various methods for pharmaceutical wastewater treatment including adsorption, filtration and advanced oxidation processes (AOP) have already been implemented by industries while researchers are working on the improvement of efficiency of those methods. Nano zero-valent iron (nZVI) particles can be used for the removal of amoxicillin (AMX) from water using one of the AOP methods – heterogeneous Fenton-like reaction. [1] In this work, we conducted two sets of experiments for removal of AMX. First experiments of AMX removal were carried out using bare commercial nZVI particles with different mass concentration (7.5, 12.5 and 25 mg). In the second set of removal experiments two different types of synthetized hydrogels were used. Both of them are copolymers of cellulose and poly(2-(dimethylamino)ethyl methacrylate), molar ratio of 1:3, and contain silica nanofiller. At the same time, they differ because hydrogel 1-3 KSP was not irradiated and 1-3 KSZ was irradiated with gamma radiation of 100 kGy. Finally, those hydrogels were submerged in water dispersions of commercial nZVI particles of different mass concentrations (75, 125 and 250 mg/L). AMX concentration was determined with UV-visible spectrophotometry and removal efficiency was calculated afterwards. The removal efficiency of AMX by bare nZVI increased with mass load and reached a maximum around 40%. Irradiated hydrogel composites with nZVI particles displayed decreasing removal efficiency with increasing mass load of nZVI particles. Among non-irradiated hydrogels, 1-3 KSP hydrogel with the highest mass load of nZVI showed the highest removal efficiency (around 38%). [1] S. Zha, Y. Cheng, Y. Gao, Z. Chen, M. Megharaj, R. Naidu, Chemical Engineering Journal 255 (2014) 141-148.

The new chemistries of poly(alkyl methacrylate) based additives containing different nitrogen or oxygen functional groups were developed for reduction of wear and friction of lubricanting oils. The additives were synthesized by radical copolymerization in solution of mineral, synthetic and vegetable oils. Wear reduction capacity of the additives was determined according to the standard test method EN ISO 12156-1 for 0.5 wt. % solutions of polymers in lubricating mineral base oil. The coefficient of friction was measured using the 4-ball geometry of the TA Discovery HR30 rheometer at different sliding speeds to simulate different applications and at different temperatures from -20 °C to 150 °C. The base oil solution of polymethacrylate additive with the hydoxyl functional group showed the smallest diameter of the wear scar and the lowest coefficient of friction.

Provedenim istraživanjem priređeni su kompozitni materijali na osnovi poli(metil-metakrilata) i poli(metil-metakrilat-ko-dimetilaminoetil-metakrilata) s nanocelulozom u udjelu 1, 2,5 i 5 mas. %. Metodom ex situ iz otopine dobivena je homogena raspodjela nanopunila u polimernoj matrici. Kromatografijom isključenja po veličini ustanovljeno je da jaka smična sila primijenjena pri homogenizaciji uzrokuje pucanje najvećih molekula polimera i time blago smanjenje prosjeka molekulskih masa polimerne matrice. Veća staklišta kompozita u odnosu na čiste polimerne matrice i porast staklišta s povećanjem udjela punila potvrđuju homogenost raspodjele i kompatiblnost nanoceluloze s istraživanim metakrilatnim matricama. Dodavanjem nanoceluloze povećava se hidrofilnost materijala, što olakšava tisak i može pogodovati njihovoj primjeni kao ambalažnih materijala. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna., The composite materials based on poly(methyl methacrylate) and poly(methyl methacrylate-co-dimethylaminoethyl methacrylate) with nanocellulose in the proportion of 1, 2.5, and 5 wt% were prepared. The homogeneous distribution of nanofillers in the polymer matrix was obtained from the solution by the ex situ method. Exclusion size chromatography showed that the strong shear force applied during homogenization caused the largest polymer molecules to crack and thus slightly reduce the average molecular weight of the polymer matrix. Higher glass transition temperatures of composites compared to pure polymer matrices and their increase with increasing filler content, confirm the homogeneity of distribution and compatibility of nanocellulose with the investigated methacrylate matrices. The addition of nanocellulose increases the hydrophilicity of materials, which facilitates printing and may favor their use as packaging materials. This work is licensed under a Creative Commons Attribution 4.0 International License.

Polymer macromolecules in polymer blends interact by forming strong intermolecular bonds or inter-segment forces usually via hydrogen bonds or between strong dipoles. Polymer blends, whether prepared from polymer melt or solution, are mostly immiscible at the molecular level due to their large molecular mass. The preparation of polymer blends lead to the formation of physical interactions between macromolecules. Such interactions are often localized in a specific area of the polymer macromolecule depending on the present functional groups. The phase behavior in polymer blends, which can be binary, ternary or more, can be modeled using the Flory- Huggins thermodynamic approach. Since we know that the mixture enthalpy is caused by the interactions between the different segments, the polymer-polymer interactions can be predicted by calculating the Gibbs free energy of mixing (ΔGm). Poly(methyl methacrylate) (PMMA), poly(butyl methacrylate) (PBMA), poly(hexyl methacrylate) (PHMA) were synthesized by free- radical solution polymerization. Gel permeation chromatography (GPC) was used to determine the relative molecular weight of the synthesized polymers which was used to calculate the Gibbs free energy of mixing. The obtained polymers were dissolved in a common solvent to form a polymer blend. Cellulose nanocrystals were then added to the prepared polymer blends to observe whether cellulose had any effect on the interactions and on the thermal properties, which were monitored by differential scanning calorimetry (DSC). The results showed that the addition of PBMA or PHMA to the PMMA with cellulose nanocrystals changed the interactions of the polymer blends.

Polialkilmetakrilatni aditivi (PAMA) već se široko primjenjuju u mazivim uljima zahvaljujući tome što ih se vrlo jednostavno može kemijski izmijeniti dodatkom različitih metakrilatnih komonomera zbog slične kopolimerizacijske aktivnosti. Koriste se u cilju poboljšanja reoloških svojstava, indeksa viskoznosti te kao snižavala točke tečenja. Ukupni sastav kopolimera potrebno je poboljšati kako bi se, osim već navedenih, mogli ispuniti zahtjevi za oksidacijskom, toplinskom i smičnom stabilnosti kao i dobrom topljivosti u mazivom ulju. Ono što definira svojstva metakrilatnih aditiva su bočni lanci različite strukture. Kokristalizacijom s parafinima iz ulja snižavala tecišta sprječavaju stvaranje gela i taloženje kristala pomoću dugačkih nepolarnih bočnih lanaca koji formiraju strukturu sličnu češlju. Također, moguće je postići i disperzantna svojstva aditiva inkorporacijom polarnog heteroatoma u bočni lanac, poput dušika ili kisika. Za ispitivane PAMA i PSAMA aditive koji sadrže funkcionalni dimetilaminoetil metakrilat (DMAEMA) u mazivom PAO 4 ulju diferencijalnom pretražnom kalorimetrijom utvrđeno je da s povećanjem udjela DMAEMA (0 – 10 mol. %) dolazi do sniženja temperature (za do 4 °C) i entalpije kristalizacije (za do 30 %) te udjela kristalne faze kopolimera (za do 25 %). Također, utvrđeno je da povećanjem molekulske mase polimera dolazi do smanjenja temperature kristalizacije ulja.

Alkil metakrilatni polimerni aditivi (PAMA) poznati su kao poboljšavala svojstava mazivih ulja poput reoloških svojstava, viskoznosti, indeksa viskoznosti i točke tečenja motornih i transmisijskih ulja. Široku primjenu ovih polimernih aditiva jednakog osnovnog lanca omogućavaju dobro definirana struktura i sastav, a ono iz čega proizlaze različita svojstva metakrilatnih polimera jesu bočni lanci različite duljine i strukture. Također, inkorporacijom stirena u lanac (PSAMA), dobivaju se polimeri poboljšane toplinske stabilnosti. Toplinsko- oksidacijskom razgradnjom mazivog ulja mogu nastati polarni produkti koji se talože i stvaraju mulj na vitalnim dijelovima motora. Uvođenjem funkcionalnog komonomera koji sadrži polarni kisikov ili dušikov atom u bočnom lancu postižu se disperzantna svojstva čime se smanjuje potrošnja goriva i poboljšava mazivost. Aditivi su u ovom istraživanju sintetizirani radikalskom kopolimerizacijom stirena ili metil metakrilata s dodecil metakrilatom, oktadecil metakrilatom u molarnim udjelima od 30 do 35 % dok je funkcionalni dimetilaminoetil metakrilat dodavan u manjem udjelu od 0 do 10 mol.%. Kako bi se dobio uvid u interakcije PAMA i PSAMA aditiva izračunati su parametri međudjelovanja (Λ12) i Gibbsove energije miješanja (ΔGM), korištenjem Coleman, Graf i Painter metodologije. Rezultati ukazuju da povećanjem udjela DMAEMA dolazi do povećanja parametra međudjelovanja što ukazuje na smanjenje interakcija između kopolimera i mazivog ulja. Također, ΔGM vrijednosti su negativne, što ukazuje na mješljivost u sustavu.

Hibridni materijali, još se nazivaju i hibridnim kompozitima, su novi materijali koji, ukoliko se postignu određene interakcije između konstituenata, pokazuju dobra svojstva oba materijala. Međutim, za to je potrebno ostvariti zadovoljavajuće interakcije, bilo kemijske, molekulske ili strukturne, između konstituenata nanometarskih dimenzija. Prilikom sinteze hibridnog punila u ovom radu korištena su dva komercijalna nanopunila, nSiO2 i nTiO2, koja su služila kao nosači za sintetizirane željezove nanočestice bez naboja (nano zerovalent iron, nZVI). Za usporedbu, na isti način, kemijskom sintezom sintetizirane i čestice nZVI. U oba slučaja nZVI stabilizirane su dipikolinskom kiselinom (PDCA). Sintetizirana hibridna punila karakterizirana su različitim tehnikama. Veličina čestica mjerena je DLS metodom na ZetaSizeru. Spektroskopijom u ultraljubičastom i vidljivom području (UV-VIS) potvrđena je prisutnost konstituenata u hibridnom punilu putem apsorbancije UV zračenja. Kemijske interakcije između konstituenata punila analizirane su korištenjem infracrvene spektroskopije s Fourierovim transformacijama (FTIR analizom). Zaključno, provedena je rendgenska difrakcijska analiza (XRD) kako bi se utvrdio mineralni sastav hibridnih punila.

Ispitan je utjecaj različitog sastava polimernog aditiva na mazivost i tecište mineralnog ulja, Yubase 4.

Celuloza, biorazgradiv i biokompatibilan polisaharid, ima tendenciju stvaranja fizikalno umreženog hidrogela stvaranjem vodikovih veza između mnogobrojnih OH skupina u molekuli. Celulozni hidrogelovi različitih vrijednosti stupnja bubrenja te određenih mehaničkih svojstva pripremaju se kontrolom procesa regeneracije (geliranja) celuloze iz otopine kroz odabir pogodnog organskog otapala za regeneraciju, optimiranjem vremena geliranja te sastava otopine celuloze. Modifikacijom celuloznih hidrogelova s različitim funkcionalnim polimerima moguće je pripremiti materijale koji zbog specifičnih svojstava nalaze svoju primjenu u različitim procesima, poput adsorbensa u porocesima pročišćavanja voda od teških metala, materijala za primjenu u tkivnom inženjerstvu te materijala za primjenu u nosivoj elektronici. Poli(vinil-pirolidon) (PVP) biokompatibilan je i vodotopljiv sintetski polimer koji zbog svoje strukture ima tendenciju stvaranja vodikovih veza s organskim molekulama te mogućnost koordinacije s metalnim ionima. U ovom radu ispitan je utjecaj deionizirane vode te organskih otapala (etanol, aceton) na regeneraciju celuloze iz otopine dimetilacetamid (DMAc)/LiCl ili otopine celuloze i PVP u istom otapalu. Također, provedeno je grafitiranje PVP na celulozu pomoću ionizirajućeg zračenja dozom od 200 kGy te je potom istraženo geliranje tako modificirane celuloze s PVP. Gravimetrijski je određen stupanj bubrenja za pripremljene hidrogelove. Nadalje, sastav pripremljenih hidrogelova karakteriziran je infracrvenom spektroskopijom, a mehanička svojstva određena su dinamičko mehaničkom analizom. Najviši stupanj bubrenja za celulozni hidrogel (1200 %) postignut je prilikom regeneracije s parama acetona, dok je za hidrogel celuloza/PVP najviši stupanj bubrenja (2000 %) zabilježen regeneracijom u parama etanola.

Dugoročna stabilnost nanofluida jedan je osnovnih zahtjeva koji mora biti zadovoljen da bi se omogućio prijenos topline u rashladnim sustavima. Zbog tendencije nanočestica aglomeraciji uslijed djelovanja Van der Waalsovih sila, dolazi do ubrzane sedimentacije pod utjecajem gravitacijske sile. Uslijed sedimentacije nanočestica pogoršavaju se svojstva nanofluida poput toplinske vodljivosti i mazivosti. Stabilnost je uvjetovana načinom pripreme nanofluida pri čemu se za raspršenje nanočestica i razbijanje aglomerata, osim fizikalnih metoda poput ultrazvučne homogenizacije, mogu koristiti kemijske metode poput dodatka površinski aktivnih tvari. Na navedene načine može se osigurati dugoročna postojanost svojstava nanofluida koja bi omogućila primjenu u industrijske svrhe. U ovome radu ispitana je stabilnost nanofluida pod djelovanjem gravitacijske sile, a i djelovanjem centrifugalne sile u svrhu simuliranja uvjeta dugoročnije gravitacijske stabilnosti. Ispitan je učinak 0, 1 mas. % kopolimera metakrilatne osnove kao površinski aktivnih tvari na stabilnost nanofluida na osnovi višestjenčanih ugljikovih nanocijevi (MWCNT, 0, 01 mas. %) u sintetskom polialfaolefinskom baznom ulju niske viskoznosti. Kao najdjelotvornija površinski aktivna tvar pokazao se kopolimer s funkcionalnom amino skupinom (A2) osiguravajući 99, 5% početne raspršenosti MWCNT nakon 28 dana i 99, 0% raspršenosti nakon izloženosti 45-minutnoj prisilnoj sedimentaciji.

Hydrogels possess unique properties in terms of porosity, swelling, mechanics, even biological responses that make them relevant to a broad range of potential applications. In order to prepare hydrogel abundant natural material cellulose, rich in hydroxyl groups, was modified by graft copolymerization with poly(2-dimethylaminoethyl methacrylate) (PDMAEMA)[1]. Hydrogles are prepared from cellulose:DMAEMA in the ratios 1:1, 1:3 or 1:5 and crosslinked with N, N-methylenebis(acrylamide) i) via chemical synthesis or ii) by additional irradiation (10, 30 or 100 kGy) [2]. The hydrogel spheres have been prepared and their swelling kinetics was studied in deionized water at 20 °C for 14 days. The swelling study of hydrogels prepared by chemical synthesis showed large equilibrium swelling (600 to 900 %). Samples 1-3_CP and 1-5_CP reached the maximum swelling degree in two days, while sample 1-1_CP reached it in seven days, suggesting that PDMAEMA contributes to the faster swelling. Selected samples were structurally characterized by scanning electron microscopy and recorded micrographics revealed structural differences related to the content of PDMAEMA.

Preservatives are natural or synthetic substances added to products in order to inhibit or retard spoilage (development of microorganisms). Their application can improve not only product’s shelf life by preventing microbial deterioration, but also its initial properties and appearance. Preservatives are especially important in the preservation of water-based products with biodegradable constituents. Waste emulsion for road construction was homogenized and enhanced by additives. Emulsion properties such as its appearance, odour and physical changes were observed in order to determine its stability. It was found that an additivized emulsion was susceptible to microbial deterioration only 7 days after its preparation. In this research, application of four different preservatives (sodium acetate, sodium benzoate, potassium metabisulfite and Preventol® B2) was investigated in order to prolong shelf life of an enhanced waste emulsion. Emulsions with various concentrations of preservatives were prepared and monitored daily during eight weeks for changes in appearance and odour caused by microbial deterioration. It was found that the addition of sodium benzoate and potassium metabisulfite in lowest tested concentrations (0.25 g preservative per 100 g non-additivized emulsion) was successful in preventing microbial deterioration since no changes in odour or appearance have occurred throughout eight weeks. However, detailed microbiological investigation should be obtained in order to confirm these findings.

Održivost (engl. sustainability) temeljni je izazov u 21. stoljeću za proizvodne industrije, od kojih se traži da primjenjuju kružno gospodarstvo te provedu tranziciju prema biogospodarstvu oslanjajući se na biosirovine. Otkrićem i razvojem zelenih otapala, koja mogu zamijeniti široko korištena organska toksična otapala petrokemijske industrije, postupno će se sve više proizvoditi u skladu s temeljnim načelima zelene kemije. Na taj način utjecat će se na ublažavanje klimatskih promjena kojima svjedočimo zbog rastuće potrebe za energijom i kemikalijama. U ovom radu, kao zeleno netoksično otapalo korišten je dihidrolevoglukozenon koji se sintetizira iz obnovljivog celuloznog otpada proizvodnim procesom koji je energetski izuzetno prihvatljiv, a kao nusprodukt u sintezi nastaje voda. Radikalskom polimerizacijom u dihidrolevoglukozenonu sintetiziran je metakrilatni polimer, poli(metil-metakrilat) (PMMA). Osim što je u sintezi korišteno zeleno otapalo, dodatni pozitivan učinak je sedam puta skraćeno vrijeme polimerizacije pri čemu se prema GPC analizi molekulska masa polimera povećala u odnosu na sintezu u standardnim organskim otapalima, a da je pri tome poboljšana i polidisperznost polimernih makromolekula. NMR analizom utvrđeno je iskorištenje reakcije i struktura PMMA polimera, dok je FTIR analizom potvrđeno da nema zaostalog otapala. DSC analizom pratili su se temperaturni prijelazi, dok se TGA analiza koristila s ciljem određivanja temperature degradacije PMMA dobivenog u standardnom organskom otapalu i u zelenom otapalu

The main aim of circular economy is to eliminate waste by continual use of resources. Circular systems employ reuse, sharing, repair, refurbishment, remanufacturing and recycling to create a closed-loop system, minimizing the use of resource inputs and the creation of waste and pollution, including the carbon emissions. Waste materials and energy become an integral part or resource for another industrial process or natural cycles such as compost production. Thus, petroleum waste can be used for the production of insulating materials or water in oil emulsions with specific use in road construction. In this study the general thermal and calorimetric behavior of water in oil emulsions of various compositions were analyzed by the thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Further, the same techniques were used for the precise determination of water content, thermal and oxidative stability.

In this work cellulose/poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) copolymers were synthesized. The nanofiller SiO2 was added in order to construct nanocomposites. The polymer films were casted directly after synthesis, while the nanocomposites were casted after mixing in the SiO2 filler and additional exposure of the mixture to an absorbed dose (100 kGy) of γ-rays from a 60Co source. Finally, water responsive cellulose/poly(2-(dimethylamino)ethyl methacrylate) and cellulose/poly(2- (dimethylamino)ethyl methacrylate)/SiO2 nanocomposite hydrogels and films were successfully prepared. The chemical reaction of cellulose and 2-(dimethylamino)ethyl methacrylate (DMAEMA) (ratio 1:1 ; 1:3 and 1:5 mol/mol) was carried out in the solvent N, N-dimethyl acetamide/LiCl with a peroxide initiator at 90 °C and using N, N-methylene-bis-acrylamide as a crosslinker. The microstructure and properties of prepared hydrogels and films were investigated by scanning electron microscopy, water contact angle, thermogravimetric analyses (TGA), while the swelling ability was followed gravimetrically. The prepared hydrogels displayed high degree of swelling, between 600 and 900 %. All hydrogels showed hydrophilic surfaces whereat with increasing share of PDMAEMA the contact angle increased from a minimum of 40° for sample from the 1:1 series to a maximum of 53° for sample from the 1:5 series. Based on SEM micrographs the SiO2 nanofiller were well dispersed as no agglomerates were visible. The TGA reveals that all samples display the main mass loss at temperatures above 300 °C where amorphous cellulose and second PDMAEMA mass losses add up. A significant signal in the 1-5 series recorded around 430 °C corresponds to the third mass loss of increased share of PDMAEMA. At temperatures up to 600 ° C the samples show high residue content common to amorphous cellulose.

Emulsions are defined as thermodynamically unstable systems of two or more immiscible liquids in which one phase is dispersed in another. Stability of emulsion refers to the ability of emulsions to resist changes in physicochemical properties over a period of time. Destabilization of emulsions can occur as gravitational separation (creaming / sedimentation), flocculation, coalescence, phase inversion and Ostwald ripening. Factors affecting the stability of emulsions are preparation conditions, the composition of the emulsion and the properties of the dispersed phase (concentration and size of droplets, droplet charge, interactions). The fastest and cheapest method of stability monitoring is visual monitoring of the separation of the emulsion’s phases. However, the stability of emulsions containing droplets smaller than 100 μm can't be detected visually. Optical microscopy is widely used as a simple technique that allows monitoring of the stability of emulsions, size and distribution of droplets in the emulsion over a long period of time. In this way the destabilization can be monitored by visual observation of the size of droplet and phase separation. In this work, the stability of prepared emulsions was monitored using optical microscopy by taking samples from the top, middle and bottom of the container and observing the stability at 10x and 20x magnification over some period of time.

Oil-soluble poly(methacrylate) based polymer additives play a significant role in lubricating base oil properties improvement, where increased viscosity at elevated temperatures ensures sufficient lubricity over a broad temperature range. Methacrylates with medium size lateral alkyl groups (C10 –C14) enhance viscosity index and those with the long chain groups (C16-C18) mostly contribute to the lowering of the pour point of solutions, whereas the methyl group contributes to the stiffness of the polymer chain. To simulate industrial process, polymerizations were conducted in batch reactor directly in base oil. Mixture of monomers (different methacrylates: methyl methacrylate, N, N-dimethylaminoethyl methacrylate, dodecyl methacrylate, octadecyl methacrylate and styrene) was added to mineral or synthetic polyalphaolefin base oil and in this way, after the polymerization, product is ready for dilution and packaging. Chain transfer agent and different initiator types were used to tailor the product toward more shear stable additive with lower molar mass. To confirm the molar mass of polymers gel permeation chromatography was used. We developed an industry ready process that can be used to synthetize wide range of polymer additives having different molar masses.

Cellulose acetate (CA), a bio-based polymer, is widely used to make membranes for water treatment and gas separation. The CA has good hydrofilzity, good separation properties in desalination processes, high water fluxes. However, CA membranes are susceptible to biofouling and microbial attack. Modification of CA membranes with amphiphilic polymers such as poly(dimethylaminoethyl (PDMAEMA) copolymer can influence the antifouling properties. The miscibility of the components in the polymer blend can affect the morphology of the prepared membrane and hence the membrane properties such as pure water flux and separation. Herein, polymer blends of cellulose acetate (acetylation degree 39.8% and 43.4%) and P(methyl- methacrylate-co-dimethylaminoethyl- methacrylate) were prepared by solution blending in a wide range of compositions (25-75 mas. %). The three- component solvent acetone/dioxane/water was used to prepare the samples of cellulose diacetate (CDA) (acetylation degree 39.8 %) based polymer blends, while acetone/dioxane/methanol was used to prepare the samples of cellulose triacetate (CTA) (acetylation degree 43.4 %). These solvents are commonly used in the preparation of cellulose acetate membranes. The miscibility of CA and P(MMA-co-DMAEMA) in polymer blends was investigated by differential scanning calorimetry. Miscible polymer blends exhibit a glass transition temperature, while partially miscible and immiscible blends exhibit glass transitions of each component. Contact angle measurements were also performed with water and diiodhomethane to calculate the free energy of CA and P(MMA-co-DMAEMA). The wetting coefficient (S), parameter that indicates wetting of one component with the other, was calculated based on the surface free energy of CA and P(MMA-co-DMAEMA). Both blends, CDA and CTA based, exhibited glass transition (Tg) for both components, indicating the presence of two phases in the polymer film. The Tg of P(MMA-co-DMAEMA) increased towards higher temperatures for 21-27 °C, while the Tg of cellulose acetate changed slightly (decrease up to 2 °C). Such increase in the Tg of P(MMA-co-DMAEMA) indicates partial mixing of the components in the P(MMA-co-DMAEMA)-rich phase.

Polymers based on alkyl methacrylates are widely used as additives for modifying the rheology of lubricating oils, where they serve as viscosity thickeners, viscosity index improvers and pour point depressants. It was established that methacrylates with medium size lateral alky groups (C10-C14) enhance viscosity index and those with the long chain groups (C16-C18) mostly contribute to the lowering of the pour point of solutions, whereas the methyl group contributes to the stiffness of the polymer chain. Also, polymers for lubricating purpose should have high shear stress stability over broad temperature range as the conditions found in lubricating environment require. Thus, to have multiple functionalities, additives should have high thermal and oxidative stability which can be achieved by addition of styrene comonomer units. [1, 2] Free radical polymerizations of monomers were carried out at 95 °C in mineral base oil using tert-butyl- peroxy-2-etilhexanoate as initiator and n- dodecyl mercaptane as chain transfer agent. There are two groups of polymers containing same comonomers: N, N-dimethylaminoethyl methacrylate (DMAEMA), dodecyl methacrylate (DDMA) and octadecyl methacrylate (ODMA) differentiating in one comonomer: styrene (ST) and methyl methacrylate (MMA). Synthesized polymers of different molar mass and composition were analysed using differential scanning calorimetry to determine phase transitions (glass transition temperature, melting point and crystallization temperature). Also, thermogravimetric analysis was carried out to investigate thermal and oxidative stability.

Ester resin has electrical insulating properties and low thermal conductivity. With the addition of nano-sized carbon fillers, a polymer nanocomposite with higher thermal and electrical conductivity can be produced. The interface and adhesive interactions between polymer matrix and filler have a significant impact on the properties of polymer nanocomposites. Five types of carbon fillers were used in this paper: carbon black nanoparticles (CB), long multi-walled (L-MWCNT), short multi-walled (S-MWCNT), long multi-walled functionalized with carboxyl group (L-MWCNT-COOH) and short multi-walled carbon nanotubes with carboxyl group (S-MWCNT-COOH) with mass fractions of 0.5, 1 and 5 wt %. Thermal properties were determined by measuring thermal conductivity by the “hot bridge“ method and the thermal stability of prepared nanocomposites were observed by thermogravimetric method (TGA). The addition of 1 and 5 wt % of carbon nanoparticles increases the thermal conductivity and did not affect the thermal stability.

Requirements regarding the less harmful emissions and increasing fuel efficiency of internal combustion engines govern the development of modern lubricating oils towards lower viscosity grade and multi-functional, highly efficient additives. Here, two additives, namely viscosity index improvers and friction modifiers play the most important role. Among the polymeric additives commonly used as viscosity index improvers, poly(alkyl methacrylates) (PAMA) provide the easiest way of changing the composition and structure that are necessary to comply with the new engine oil specifications. PAMA additives are manufactured by the free radical copolymerization of corresponding methacrylate monomers in solution of lubricating base oil. Therefore, they can relatively simply be chemically modified by the addition of different functional methacrylate comonomers because of similar copolymerization reactivity. This is their noteworthy advantage over the competing additives such as polyolefins or styrene/butadiene/isoprene copolymers that are prepared by metallocene or anionic polymerization where chemical modification is a much more complicated and demanding process. In addition to the viscosity index improving, the additives based on PAMA are well known and widely used pour point depressants of lubricating oils. They prevent gelation of the oil and deposition of n-paraffins from the base oil at low temperatures and enable oil to flow at much lower temperatures. This paper will present the results of synthesis and properties of new dispersant PAMA additives of improved solubility, shear and thermal stability, while maintaining excellent properties of improving the viscosity index and lowering the pour point of lubricating oil.

Environmental protection issues and rational use of natural resources are becoming the focus of attention nowadays. It has been found that the construction of road infrastructure is one of the most polluting activities. Road construction is accompanied by a number of processes that directly or indirectly affect the environment. Dust, noise and vibrations are the three most damaging effects of road construction and management. However, good condition of pavement could have a significant influence on noise and vibration reduction, fuel consumption, reduction of CO2 emissions, and even on road accidents. Optimizing industrial processes, creating a quality infrastructure and making it as sustainable as possible is a step towards the environment protection during road construction. Circular economy is an approach to sustainable development which creates value and prosperity through extending product lifespan and relocating waste from the end of the supply chain to the beginning. In a circular economy, materials for new products come from old products by reusing, re-manufacturing or recycling. It is said that the circular economy could save European businesses up to $630 billion a year. Waste oil from oil refinery plants mixed with water and a biopolymer creates a water emulsion suitable for using in construction of road infrastructure. The aim of this work is to determine the thermal stability of waste oil/water emulsion. Emulsion stability was investigated by conducting rheology measurements at 30 °C and 60 °C, microscopy analysis of droplet size distribution and subjecting emulsion to laboratory centrifuge at elevated temperatures.

Prijedlog strategije razvoja i tehnologija za razdoblje od 2020. do 2030.

Polylactic acid (PLA) is a polymer that has had a huge impact on the evolution of the bioplastics industry during the last 30 years. It is linear thermoplastic polyester derived from renewable sources that displays properties such as bio-compatibility, bio-degradability as well as the ability to be molded into different shapes. The latest endeavours are moving toward durable bioplastics, which is desired for long-term multiuse application in automotive, electronics, and other industries. The main goal of this work was to show a simple method of preparation of polylactide nanocomposites using a synthesized hybrid filler nSiO2@Fe. Hybrid filler was used to possibly, in any way, affect electric properties of produced PLA nanocomposites. Hybrid filler was synthesized using a method of reducing an iron salt (FeCl3) to elemental iron, also known as zero-valent nano iron (nZVI, Fe0), with NaBH4 as a reducing agent of the chemical reaction.[1] Nanosilica was used as a carrier for the reduced nZVI particles. Nanocomposite material was produced using the melt-mixing method. PLA was used as a composite matrix, to which commercial silica nanoparticles (nSiO2) and new synthesized hybrid nanoparticles of silica and iron nanoparticles (nSiO2@Fe) were mixed as filler with different mass ratios (1 % nanosilica, 1 % nanosilica +0.05 % hybrid filler, 0.5 % nanosilica +0.5 % hybrid filler and 0.5 % hybrid filler). Synthesized hybrid nanoparticles were analysed using UV-VIS spectroscopy and scanning electron microscope (SEM). The size of particles was determined using the dynamic light scattering method (DLS). Results of SEM and DLS showed that synthesized nanoparticle filler nSiO2@Fe were still in range of nanometre-scale (178 ± 118, 85 nm), and with the UV-VIS spectra of the filler, we could confirm the existence of both nSiO2 and Fe0 in the hybrid particles. Structural and thermal properties of pressed nanocomposites were analysed ; SEM micrographics showed that mainly a homogeneous dispersion of both nanofillers was achieved. Only one of the samples showed a nonuniform dispersion and formation of large agglomerates of fillers in the matrix (0.5 % nanosilica + 0.5 % hybrid filler). Performed measurements of thermal conductivity and electric resistivity reveal that the thermal conductivity of the PLA nanocomposites was not affected by the addition of nanosilica or hybrid nanofillers. As expected, nSiO2@Fe hybrid filler had an impact on the electric properties of the nanocomposite. The properties improved because hybrid filler had lowered the values of measured electric resistance of the PLA nanocomposites. Electric properties of nanocomposites were highly conditioned by the dispersion of the nSiO2@Fe hybrid filler in the PLA matrix, which is consistent with the SEM results.

Mineralna gnojiva osiguravaju hranjive tvari usjevima i pospješuju njihov rast te istovremeno igraju važnu ulogu u reguliranju pH i plodnosti tla. No, nekontrolirana uporaba mineralnih gnojiva može dovesti do neželjenih efekata kod biljaka [1]. Zbog toga, posljednih desetljeća sve se više pridaje važnost proizvodnji i uporabi gnojiva sa sporim ili kontroliranim otpuštanjem aktivne tvari što predstavlja učinkovitije gospodarenje hranjivim tvarima u biljkama, čime se smanjuju potencijalne ekološke prijetnje uz zadržavanje visokog kvaliteta usjeva. Upotreba takvog gnojiva osigurava povećan agronomski učinak, rezultira većim prinosima, poboljšanjem kvaliteta i izgleda usjeva te u konačnici uštedom radne snage [2]. Apsorpcija fosfora u biljkama je prilično niska, što predstavlja ozbiljan problem za rast usjeva, budući da fosfor ima najvažniju ulogu u korijenskom sustavu. Ovakav problem moguće je riješiti korištenjem gnojiva sa sporim ili kontroliranim otpuštanjem aktivne tvari koje se može pripremiti oblaganjem granula različitim polimernim materijalima koji smanjuju brzinu otapanja granula. Brzine otpuštanja i otapanja u vodi topljivih gnojiva ovise o vrsti materijala za oblaganje kao i debljini sloja. Celulozni acetat (CA) se pokazao kao najprivlačniji polimerni materijal za oblaganje gnojiva zbog svoje biorazgradljivosti, netoksičnosti i niske cijene. U ovom radu, komercijalno granulirano gnojivo NPK15-15-15 (Petrokemija d.d.) obloženo je otopinom CA u acetonu (2, 3 i 5 mas.% CA) u rotacijskom bubnju. Debljina polimernog sloja analizirana je pretražnom elektronskom mikroskopijom (SEM), dok je profil brzine otpuštanja fosfora analiziran UV-Vis spektroskopijom. Ustanovljeno je da koncentracija priređene otopine CA ne utječe na debljinu polimernog filma. Nakon 10 nanošenja debljina filma iznosila je oko 20 μm za sve koncentracije polimera (2, 3 i 5 mas.% CA). Međutim, SEM analiza pokazala je da je najkompaktniji polimerni film na površini granula dobiven uporabom otopine 3 mas.% CA. S povećanjem broja ciklusa nanošenja povećana je debljina polimernog filma što je rezultiralo produženim oslobađanjem fosfora iz obloženih granula gnojiva.

Analiza i usporedba sastava i strukture komercijalnih filtarskih polumaski.

Ovo posebno izdanje “Kemije u industriji” donosi odabrane radove koji su prezentirani na VII. hrvatskom simpoziju o kemiji i tehnologiji makromolekula – Eko-dizajn za kružno gospodarstvo, održanom u Zagrebu 27. rujna 2019. godine u Hrvatskoj gospodarskoj komori. Svi radovi prošli su standardni postupak recenziranja. VII. hrvatski simpozij o kemiji i tehnologiji makromolekula znanstveni je i stručni skup koji su zajednički organizirali Fakultet kemijskog inženjerstva i tehnologije, Hrvatsko društvo kemijskih inženjera i tehnologa (Sekcija za makromolekule i Sekcija za kemijsko inženjerstvo) i Hrvatska gospodarska komora. Tradicionalno, svrha je skupa okupljanje sudionika iz znanstvene i gospodarske zajednice u Hrvatskoj koji se bave kemijom i tehnologijom polimera radi uspostave ili unaprjeđenja međusobne suradnje s posebnim naglaskom na eko-dizajn i kružno gospodarstvo u razvoju i proizvodnji inoviranih polimernih materijala. Rad skupa odvijao se kroz usmene sekcije: Kroz suradnju znanosti i industrije do eko dizajna, Unaprjeđenja u području polimernih materijala, Primjeri kružnog gospodarstva: kompostabilni polimeri i predstavljanje Circ-pack projekta i postignutih glavnih inovacija, postersku sekciju i okrugli stol. Skupu je prisustvovalo 115 sudionika. U ime Organizacijskog odbora VII. hrvatskog simpozija o kemiji i tehnologiji makromolekula – Eko dizajn za kružno gospodarstvo zahvaljujemo sponzorima i svim sudionicima koji su svojim sudjelovanjem doprinijeli uspjehu Simpozija.

Kopolimeri na osnovi alkil-metakrilata često se koriste kao aditivi u mazivim uljima pri čemu utječu na njihova reološka svojstva i tecište. Terpolimerizacijom alkil-metakrilatnih monomera s nekim funkcionalnim komonomerom, primjerice tert-butilaminoetil-metakrilataom, otvara se mogućnost značajnog utjecaja na primjenska svojstva kao što su adhezivnost, hidrofobnost, topljivost, i slično. Kako bi se sintetizirali polimeri željenog sastava potrebno je poznavati omjere kopolimerizacijske reaktivnosti s obzirom da o njima ovisi sastav nastalog polimera. Jednostavna procjena omjera kopolimerizacijske reaktivnosti ternarnih sustava koristi omjere kopolimerizacijske reaktivnosti dobivene za binarne sustave odgovarajućih monomernih parova. Na taj način zanemaruje se utjecaj trećeg komonomera na proces polimerizacije što često dovodi do pogrešne procjene parametara kopolimerizacijske reaktivnosti i pogrešne procjene sastava terpolimera. U ovom radu izračun omjera kopolimerizacijske reaktivnosti za ternarni sustav proveden je pomoću preoblikovane Alfrey-Goldfingerove jednadžbe. Nadalje, za izračun je korištena metoda koja uzima u obzir postojanje pogrešaka u zavisnim i nezavisnim varijablama (engl. Errors in Variables Model). Priprava terpolimera iz monomera metil-metakrilata, oktadecil-metakrilata i tert-butilaminoetil-metakrilata provedena je reakcijom polimerizacije do niskih konverzija (< 10 mas. %) izotermalno pri temperaturi od 70 °C uz peroksidni inicijator. Sastav terpolimera određen je pomoću NMR spektroskopije.

Analiza sastava, veličine vlakana filtarske polumaske za zaštitu od čestica.

olekulna hibridizacija pomoću poznatih farmakofora novi je pristup sintezi biološki aktivnih spojeva. Jedan od poznatih farmakofora je benzofenon. Derivati benzofenona javljaju se u prirodi i specifični su za porodicu biljaka kluzijevki (Clusiaceace), a pokazuju biološku aktivnost (antibakterijska svojstva, anti-HIV aktivnost, protuupalno djelovanje, inhibiciju rasta stanica karcinoma). Biološka aktivnost je utvrđena i kod sintetskih derivata benzofenona. Primjerice, ketoprofen dostupan je na tržištu kao protuupalni lijek. Također, poznati farmakofor je 1, 2, 3- triazolna skupina. Otporan je na metaboličku degradaciju, omogućava stvaranje vodikovih veza i poboljšava vezanje pripadajuće molekule na biološke mete. Jednostavna sinteza 1, 2, 3- triazola kroz reakciju azid-alken cikloadicije, koja je katalizirana solima bakra, uzrok je čestog odabira triazolne skupine prilikom sinteze novih biološki aktivnih spojeva. U ovom radu provedena je sinteza 4-(4-(hidroksimetil)-1H-1, 2, 3- triazol-1-il)benzofenona (1) iz 4-azidobenzofenona i propagil alkohola uz primjenu Cu+ ili Cu2+ soli kao katalizatora. Upotrebom Cu2+ soli u različitim otapalima (metanol, tetrahidrofuran) uspješno je sintetiziran spoj 1. Nasuprot tome, u sustavu s Cu+ kao katalizatorom u otapalu N, N- dimetilformamid/voda nije došlo do nastanka spoja 1. Sintetizirani spoj karakteriziran je spektroskopijom nuklearne magnetne rezonancije i infracrvenom spektroskopijom.