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Title:SINTEZA FUNKCIONALNIH ZAMREŽENIH MAKROMOLEKUL IZ EMULZIJ
Authors:Sevšek, Urška (Author)
Krajnc, Peter (Mentor) More about this mentor... New window
Files:.pdf DR_Sevsek_Urska_2014.pdf (4,50 MB)
 
Language:Slovenian
Work type:Dissertation (m)
Typology:2.08 - Doctoral Dissertation
Organization:FKKT - Faculty of Chemistry and Chemical Engineering
Abstract:V okviru doktorske disertacije smo pripravili porozne polimere z verižno radikalsko polimerizacijo emulzij z visokim deležem notranje faze na osnovi monomera stirena in zamreževala divinilbenzena, iniciirano termično ali fotokemično. Spreminjali smo delež zamreževala in preučili njegov vpliv na morfologijo nastalega polimera in količino preostalih vinilnih vezi v polimerni matriki. V omenjen nepolarni sistem smo vključili delno polarno metakrilno kislino ter s tem v polimerno matriko uvedli funkcionalno karboksilno skupino. Stabilnost emulzije smo dosegli z uporabo ustrezne kombinacije surfaktantov. Maksimalen delež metakrilne kisline, ki smo jo lahko dodali emulziji, je bil 20 mol %. Kot metodo polimerizacije smo uporabili fotopolimerizacijo, saj je pri uporabi termično iniciirane radikalske verižne polimerizacije prihajalo do prehajanja metakrilne kisline v vodno fazo emulzije. Pri fotopolimerizaciji konverzija iz monomera v polimer poteka precej hitreje in metakrilna kislina je ostala v organski fazi. Rezultat je bil porozen poliHIPE material s kislinskimi skupinami in tipično poliHIPE strukturo. Kislinske skupine smo funkcionalizirali s tionil kloridom do kislinskega klorida. Uspešnost konverzije je bila 76-odstotna. Funkcionalnost polimera smo preizkusili z reakcijo nukleofilne substitucije z bifunkcionalnimi amini. Preverili smo, kako koncentracija diamina in dolžina ogljikove verige vplivata na uspešnost konverzije ter na strukturo produkta. Pri uporabi diamina z daljšo ogljikovo verigo je bila konverzija za 10 % boljša od konverzije, kjer smo uporabili krajši diamin. Pri uporabi daljšega diamina se je z zviševanjem koncentracije le-tega povečevala stopnja konverzije, medtem ko pri uporabi krajšega diamina tega efekta ni bilo opaziti. V drugem delu doktorske disertacije smo pripravili porozne poli(stiren-ko-divinilbenzen) polimere z deležem zamreževala med 37 in 80 mol %. Preverili smo vpliv deleža zamreževala na BET specifično površino in ugotovili trend naraščanja le-te z višanjem deleža zamreževala. Iz spektrov infrardeče spektroskopije smo določili delež preostalih vinilnih vezi v polimerni matriki. Da bi na polimer uvedli funkcionalne skupine, smo izvedli funkcionalizacijo z multifunkcionalnimi tioli. Uporabili smo tiol z dvema in štirimi tiolnimi skupinami. Nato smo na graftiran polimer vezali še bifunkcionalni alken. Izkoristek funkcionalizacije se je večal z višanjem deleža zamreževala, najvišja dosežena stopnja konverzije je bila 44 %. Višje konverzije smo dosegali z uporabo tiola z dvema tiolnima skupinama. Pri primerjavi porazdelitve velikost mezopor smo opazili, da je po funkcionalizaciji prišlo do zmanjšanja števila le-teh. Izkazalo se je, da je za to odgovorno topilo, ki smo ga uporabili. Poizkusili smo še enostopenjsko funkcionalizacijo, kjer smo v reakcijsko mešanico dodali tako ditiol kot bifunkcionalni alken. V tem primeru je prišlo do precejšnjega povečanja BET specifične površine, vendar je bila stopnja konverzije dokaj nizka. Nadalje smo v poli(stiren-ko-divinilbenzen) poliHIPE material uvedli mezopore in mikropore z metodo naknadnega zamreženja oziroma hiperzamreženja. Uporabili smo peroksidni iniciator, di-tert-butil peroksid, za katerega je značilen specifičen mehanizem delovanja. Delež divinilbenzena je variiral med 52 in 80 mol %. Zanimal nas je vpliv procesa na makroskopsko morfologijo materiala. Izkazalo se je, da reakcija naknadnega zamreženja ne vpliva bistveno na morfologijo, do večjih razlik v porazdelitvi velikost primarnih por je prišlo le v primeru najmanj zamreženega vzorca. Reakcijo hiperzamreženja smo izvedli v treh topilih: toluenu, acetonitrilu in dimetilformamidu. Kot najbolj uspešno topilo se je izkazal toluen, pri katerem je v vseh primerih prišlo do največjega porasta BET specifične površine, najvišji faktor povečanja specifične površine je znašal 7,2. Prav tako je bil delež mezopor in mikropor v materialu, funkcionaliziranem v toluenu, najvišji. Pri uporabi dimetilformamida in acetonitri
Keywords:porozni polimeri, poliHIPE, polimerizacija, hiperzamreženje, polistiren, polimetakrilat, funkcionalizacija polimerov
Year of publishing:2014
Publisher:[U. Sevšek]
Source:Maribor
UDC:539.199:665.652.2(043.3)
COBISS_ID:17756950 Link is opened in a new window
NUK URN:URN:SI:UM:DK:KAOKPWAC
Views:1276
Downloads:258
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Categories:KTFMB - FKKT
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Secondary language

Language:English
Title:Synthesis of functional crosslinked macromolecules from emulsions
Abstract:Porous polymers have been prepared by emulsion templating and by using styrene as the monomer and divinylbenzene as the crosslinker. The polymerisation has been initiated with a radical initiator or by foto initiator. The amount of the crosslinker has been varied and its influence on morphology and amount of the remaining double bonds in the polymer matrix has been studied. Methacrylic acid has been introduced into the mentioned polymer system, therefore carboxylic group was successfully incorporated into the polymer chain. Appropriate stability of the emulsion was achieved by combining different surfactants. The highest share of methacrylic acid that could be intergrated was 20 molar percentages. Thermal initiation of the free radical polymerisation lead to partial transfer of methacrylic acid into the internal phase. Therefore photoinitiation was used because of the faster conversion from monomer to polymer and methacrylic acid remained in the organic phase. This yielded in porous poyHIPE material, containing acid groups in the polymer chain and with a typical polyHIPE structure. Carboxylic groups have been functionalised by thionyl chloride to obtain acid chloride moieties. The rate of conversion was 76 percentages. Bifunctional amines have been used in order to verify the products reactivity. The influence of amine concentration and the lenght of its carbon chain on the conversion rate and the structure of the product have been studied. The conversion rate was 10 percent higher when using 1,12-diaminododecane compared to the conversion rate when using 1,4-diaminobutane. The higher concentration of the diamine enlarged the conversion rate when using 1,12-diaminododecane, whereas by using 1,4-diaminobutane this effect was not noticed. Further on, porous poy(styrene-co-divininylbenzene) poliHIPEs have been prepared by varying the amount of the crosslinker from 37 to 80 molar percentages. The influence of the crosslinker amount on the BET surface area has been verified. A trend of increasing surface area with increasing the amount of the crosslinker has been noticed. Fourier transform infrared spectroscopy spectra have enabled us to determine the amount of the remaining double bonds in the polymer matrix. In order to incorporate functionalities into the polymer, functionalisation with multifunctional thiols was used. Thiols containing two and four thiol groups have been used. Furthermore, a bifunctional alkene has been incorporated onto the grafted polymer. The polymerisation efficiency was higher when using a higher degree of the crosslinker, the highest conversion rate was at 44 percent, where higher conversion rates were achieved when using the bithiol reagent. Mesopore size distributions have been compared between the unfunctionalised and functionalised samples and the latter revelaed a decrease in mesopore size. In was concluded that the solvent used was accountable for that. Also, a one-step functionalisation was performed, where bithiol and multifunctional alkene were included at once in the reaction mixture. In this case, a substantial increase in BET surface area was noticed, whereas the conversion rate was quite low. Hereinafter, a hypercrosslinking approach has been utilised in order to incorporate mesopores and micropores into the poly(styrene-co-divinylbenzene) matrix. A peroxy initiator, namely di-tert-butyl peroxide, that has a specific mechanism of initiation, has been used. The amount of divinylbenzene in the untreated samples varied from 52 to 80 molar percentages. We were interested in the influence of the process on the morphology of the samples. It has been shown that the hypercrosslinking reaction does not influence substantially on the morphology of the material, the greatest difference in the morphology was found in the least crosslinked sample. Three solvents have been used for the hypercrosslinking reaction: toluene, acetonitrile and dimethylformamide. In the case of using toluene, the increase in the BET surface area was significant, the highest enlargment factor amounted to 7,2 folds.
Keywords:porous polymers, polyHIPE, polymerisation, hypercrosslinking, polystyrene, polymethacrylate, functionalisation of polymers


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