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Temperaturna odvisnost samo-asociacije ataktične poli(metakrilne kisline)
Derganc, Barbara (Author), Kogej, Ksenija (Mentor) More about this mentor... This link opens in a new window

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Abstract
Proučevali smo samozdruževanje polimerov v stabilne polimerne nanodelce s spremembo temperature, kjer se samozdruževanje ne sproži z nobenimi aditivi. Običajni primer je, da v termo občutljivi polimerni raztopini med segrevanjem pride do ločitev faz. Vezi polimer-polimer postanejo bolj ugodne kot vezi polimer-topilo. Pravimo, da se kakovost topila slabša, kar vodi do tvorbe polimernih sklopov (asociatov). Naš cilj je bil preučiti temperaturno odvisnost asociacije poli(metakrilne kisline), PMA, ki je termo občutljiv in na pH občutljiv polimer. Za proučevanje asociacije smo v raztopino PMA dodajali tri tetraalkilamonijeve kloride (tetrametilamonijev klorid, tetraetilamonijev klorid in tetrapropilamonijev klorid). Samozdruževanje verig ataktične PMA in tvorbo polimernih nanodelcev ob dodatku teh soli smo spremljali z UV-Vis tehniko, kjer smo po pripravi raztopino polimerne kisline in soli segrevali in ohlajali, hkrati pa merili absorbanco UV-svetlobe. Pred tem smo določili valovno dolžino, pri kateri smo merili, da izmerjene vrednosti absorbance ne bi motilo topilo. Za kako stabilne polimerne nanodelce je šlo, smo sklepali tudi iz reverzibilnosti oz. ireverzibilnosti obarjanja. Naše domneve smo potrdili še z vizualnim opazovanjem raztopine. Izvedli smo vse korake, ki smo si jih zadali, in na osnovi dobljenih rezultatov ugotovili, da do samozdruževanja verig PMA in posledičnega obarjanja pride pri povišanju temperature. Določili smo tudi tako imenovano kritično temperaturo raztopine za vse tri izbrane kloride ter pokazali, v katerih primerih je obarjanje reverzibilno.

Language:Slovenian
Keywords:polimerni nanodelci, termoobčutljivi polimeri, poli(metakrilna kislina), samozdruževanje
Work type:Bachelor thesis/paper (mb11)
Tipology:2.11 - Undergraduate Thesis
Organization:FKKT - Faculty of Chemistry and Chemical Technology
Year:2021
COBISS.SI-ID:83321347 This link opens in a new window
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Downloads:18
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Secondary language

Language:English
Title:Temperature dependence of self-assembly of poly(methacrylic acid)
Abstract:
We studied polymer self-assembly into stable polymeric nanoparticles by changing the temperature, which is not triggered by any additives. Usually, a thermosensitive polymer solution is heated, the solvent quality gradually worsens upon heating and polymer-polymer contacts become preferred over polymer-solvent contacts, which leads to the formation of polymer assemblies. Our aim was to study the temperature dependence of self-association of poly(methacrylic acid), PMA, which is a thermo-responsive and pH-responsive polymer. Three tetraalkylammonium chlorides were added to the PMA solution to follow self-association – tetramethylammonium, tetraethylammonium and tetrapropylammonium chloride. The self-assembly of atactic poly(mehacrylic acid) chains and the formation of polymeric nanoparticles with addition of salt were monitored by the UV-Vis technique, where, after mixing, the polymeric acid and salt solution, the solution was heated and cooled, while the absorbance was measured. We have previously determined the wavelenght at which we measured the absorbance so that the measurement would not be influenced by the solvent. The stability of the polymeric nanoparticles was deduced from reversibility or irreversibility of association. The type of association was also predicted from the UV-Vis results. Later, our assumptions were comfirmed by simple visual observations. We performed all the planned experiments. The obtained results show that self-assembly of PMA takes place at elevated temperatures. So-called critical solution temperature was determined for all three chlorides. We also demonstrated in which cases the association is reversible.

Keywords:polymeric nanoparticles, thermo-responsive polymers, poly(methacrylic acid), self-assembly

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