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Mixing ionic liquids is a suitable strategy to tailor properties, e.g., to reduce melting points. The present study aims to widen the application range of low-toxic choline-based ionic liquids by studying eight binary phase diagrams of six different choline carboxylates. Five of them show eutectic points with melting points dropping by 13 to 45°C. The eutectic mixtures of choline acetate and choline 2-methylbutarate were found to melt at 45°C, which represents a remarkable melting point depression compared to the pure compounds with melting points of 81 (choline acetate) and 90°C (choline 2-methylbutarate), respectively. Besides melting points, the thermal stabilities of the choline salt mixtures were investigated to define the thermal operation range for potential practical applications of these mixtures. Typical decomposition temperatures were found between 165 and 207°C, with choline lactate exhibiting the highest thermal stability.

Väitekirja elektrooniline versioon ei sisalda publikatsioone, Edendades inimkonna tehnoloogilist progressi ning olles samas loodussäästlikud, peame välja töötama lahendused, mis ainult ei täida funktsiooni, vaid ei kehtesta ka liigset koormat loodusele. Pehmed täiturid on kasulikud biomeditsiinilistes rakendustes nende madalpingetarbimise ja mitteinvasiivse liikumise tõttu. Elektrolüütide ehk ioonsete vedelike, toksilisus materjalis, mis on vajalikud pehmete polümeeride täiturmootori liigutamiseks, on täiturite kasutusvõimalusi piiranud. Üks viis selle piirangu ületamiseks on kasutada elektrolüütidena koliin ioonseid vedelikke. Selline lähenemine võimaldaks saavutada täielikult toimiva bioühilduvat pehmet polümeertäituri. Bioühilduv pehme polümeertäitur saavutati pärast järgmisi toiminguid. Esiteks testiti üksikuid koliin ioonseid vedelikke mitmete bakteritüvede ja rakuliini peal, mida kõiki on toksikoloogia uuringutes laialdaselt kasutatud. Teiseks prooviti koliin ioonseid vedelikke kombineerida segudeks, millel on madalam sulamistemperatuur kui üksikutel komponentidel. See lihtsustab nende kasutamist madala temperatuuriga keskkonnas. Täielikult bioühilduv pehme polümeertäitur saavutati lõpuks kõikide bioühilduvate komponentide kombineerimisega ning täituri elektromehaaniliste ja toksikoloogiliste omaduste põhjaliku testimisega. Sünteesitud koliin ioonsed vedelikud olid kõikide testitud katseorganismide suhtes ohutud. Peamiseks toksilisust mõjutavaks teguriks oli toitelahuse pH muutus. Koliin ioonsete vedelike segamisel tuvastati viis kahekomponendilist segu, millel on madalam sulamistemperatuur kui nende üksikutel komponentidel. Sulamispunkti languse hulk sõltus üksikute komponentide molekulaarsest kujust. Valmistatud bioühilduv täitur ületas oma võimekuselt võrdluseks valitud täiturit, mis oli valmistatud laiemalt kasutust leiduvatest materjalidest. Samuti kinnitati, et bioühilduv täitur tervikuna ei ohusta kokkupuutel elusorganisme., For the conservation of earth, while keeping up the technological progress of humanity, we need to come up with solutions that not only fill a function, but also do not impose a penalty on nature. Soft actuators are useful in biomedical applications because of their low voltage consumption and non-invasive movement. The toxicity of the electrolytes in the material, called ionic liquids, necessary to make the soft polymer actuator move, has limited their applications. One way to overcome this limitation, is to swap the toxic components for choline ionic liquids. This approach would make it possible to achieve a fully functioning biofriendly soft polymer actuator. The biofriendly soft polymer actuator was achieved after the following research steps. First, the individual choline ionic liquids were tested against several bacterial strains and a human cell-line, which are all widely used in toxicology studies. Second, the choline ionic liquids were attempted to be combined into mixtures that have a lower melting point than the individual components. This makes them easy to use in low temperature environments. The fully biofriendly soft polymer actuator was finally achieved by combining the biofriendly components and thoroughly testing its electromechanical and toxicological properties. The synthesized choline ionic liquids were all harmless towards the selected test organisms. Moreover, the main factor influencing the toxicity, was the change in feeding solution pH. By mixing the choline ionic liquids five two-component mixtures were identified that have a lower melting point than their individual components. The amount of melting point depression depended on the molecular shape of the individual components. Lastly, the biofriendly soft polymer actuator outperformed the comparison made from more widely used soft polymer actuator materials. It was also confirmed that the biofriendly actuator as a whole was suitable for contact with living organisms., https://www.ester.ee/record=b5428762

This study reports on the successful preparation of four luminescent ionic liquids, for which melting temperatures, luminescence spectra, emission lifetime, and absolute quantum yield were measured. Based on measurement results, [P6,6,6,14][Pt(PPy)Cl2] (P6,6,6,14 = trihexyltetradecylphosphonium ion; PPy = 2-phenylpyridine) was chosen for closer investigation as most prominent of prepared materials, due to its remarkable quantum yield (at room temperature Ф = 0.40) and low melting point (Tm = 50 ℃). It was then demonstrated, that [P6,6,6,14][Pt(PPy)Cl2] has all required properties to be applied in various optoelectronic devices, such as temperature sensors and displays based on organic light-emitting diodes or electrochemical cells.

In English: In the twenty-first century, electroactive polymer actuators have found new application as artificial muscles. Previously, the bending efficiency was in the priority, that is why ionic liquids have been used as electrolytes for such type of actuators, though it was known that they are a hazard for living organisms. Since these artificial muscles are planned to be used in medical devices and human bodies, it is essential that actuators should be bio-friendly and prepared from low-toxic materials. That is why a new type of choline-based deep eutectic solvents has been tested in the current study as electrolytes for actuators. Such electrolytes could be prepared from inexpensive and low toxic materials. Additionally, in comparisons to ionic liquids, they show comparable results in displacement and exceed in capacitor like behavior. Eesti keeles: Elektroaktiivsed polümeerid on 21. sajandil leidnud laialdast tähelepanu tänu võimalusele kasutada neid tehislihastes. Varasemalt pöörati tähelepanu peamiselt nende materjalide liikumisamplituudi suurendamisele ning leiti, et ioonsete vedelike kasutamine elektrolüüdina aitab sellele kaasa. Elektroaktiivsete polümeersete täiturite üheks rakendusvaldkonnaks on mitmesugused meditsiiniseadmed, mistõttu on oluline välja töötada bioühilduvad materjalid. Traditsiooniliste ioonsete vedelike toksilisuse tõttu otsitakse neile käesolevas töös biosõbralikku alternatiivi. Testiti koliini baasil ioonseid vedelikke ja eutektilisi segusid kui madala toksilisusega elektrolüüte elektroaktiivsete polümeersete täiturite jaoks. Ioonsete vedelike ja eutektiliste segude võrdlusest selgus, et testitud süsteemides võib eutektilisi segusid kasutada asendamaks ioonseid vedelikke.

http://www.ester.ee/record=b4689514*est

http://www.ester.ee/record=b4620893*est