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Thermo-Responsive Block Copolymers: Synthesis, Self-Assembly and Membrane Development /

Record Type:	Electronic resources : Monograph/item
Title/Author:	Thermo-Responsive Block Copolymers: Synthesis, Self-Assembly and Membrane Development // Merve Mocan Cetintas.
Author:	Cetintas, Merve Mocan,
Description:	1 electronic resource (191 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 83-03, Section: B.
Contained By:	Dissertations Abstracts International83-03B.
Subject:	Membranes. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28232913
ISBN:	9798708788511

Thermo-Responsive Block Copolymers: Synthesis, Self-Assembly and Membrane Development /
Cetintas, Merve Mocan,

Thermo-Responsive Block Copolymers: Synthesis, Self-Assembly and Membrane Development /Merve Mocan Cetintas. - 1 electronic resource (191 pages)

Source: Dissertations Abstracts International, Volume: 83-03, Section: B.

Block copolymers (BCPs) are attractive materials because of their high tunability and selfassembling ability into regular morphologies in the range of 10-100 nm. They can be used for nanotechnological applications as surfactants, thin films for nanolithography, biomedicine and nanoporous membranes. In this thesis, we aimed to fabricate thermo-responsive iso- and nanoporous membranes that can be used to purify water from nano-sized impurities, also to gain a good understanding on the self-assembly properties of the BCPs.In the introduction of the thesis, given in Chapter 1, we present our scope and aim of the research and introduce the literature about the synthesis and self-assembly of block copolymers. Next, we report the fundamentals of block copolymer membranes including the block copolymer thin films, the SNIPS (self-assembly and non-solvent induced phase separation) process and stimuli-responsive block copolymer membranes.In Chapter 2, we synthesized well-defined polystyrene-poly(N-isopropylacrylamide) (PSPNIPAM) BCPs using reversible-addition-fragmentation-transfer polymerization to produce the desired membranes. Poly(N-isopropylacrylamide) (PNIPAM) is thermoresponsive which exhibits a lower critical solution temperature (LCST) of around 32 °C. This means that at temperatures lower than the LCST, the block is hydrophilic and therefore swollen in aqueous environment and when the temperature is increased above the LCST the block becomes hydrophobic and collapses. When we have the membranes, the pore sizes of the membrane should increase at temperatures above the LCST of PNIPAM, due to collapsing of the PNIPAM chains. The second block of the copolymer, polystyrene (PS), acts as the matrix thereby preventing the block copolymer from dissolving in water and maintaining mechanical stability of the membrane.We optimized the synthesis conditions to obtain BCPs with a high percentage of PS, a high yield and a low polydispersity index (PDI), which are required to produce thermoresponsive iso- and nanoporous membranes with a suitable mechanical stability. According to the literature, the best strategy to synthesize PS-PNIPAM block copolymers was suggested as first synthesizing the PS macro-RAFT agent and extending it with NIPAM monomer. However, following this route we found that when PS was chosen as the majority phase, the obtained yield of this block copolymer was rather low or even zero. Instead, when we synthesized the PNIPAM macro-RAFT agent first and extend it with styrene monomers, we obtained PS-PNIPAM block copolymers with higher yields while maintaining the low PDI values. We used two different RAFT agents to attain block copolymers with various architectures such as AB, ABA and BAB types. We used an AB type block copolymer to produce membranes. The membranes were fabricated using a SNIPS process using a 20 wt% block copolymer solution in N-methyl-2-pyrrolidone (NMP) and tetrahydrofuran (THF) with a volume ratio of 4:6. We found that by increasing the evaporation time from 10 to 80 seconds the membrane surface became more interconnected with smaller pore sizes. Permeability measurements performed from 20 to 50°C showed that the membranes were thermoresponsive and this property was found to be fully reversible when several temperature cycles of 20 and 50°C were applied.To get a deeper insight on the block copolymer self-assembly, we theoretically and experimentally investigated the behavior of block copolymers. Our theoretical work, presented in Chapter 3, employed the self-consistent field method of Scheutjens and Fleer (SF-SCF) which consisted of two parts. As the SF-SCF technique was not yet used for the microphase segregation of block copolymers, we benchmarked the calculations. For this reason, we focused on the chain length dependence of the critical point in the block copolymer phase diagram. In the critical region, we report the scaling behavior of the free energy density and the density differences between the domains as a function of ΔX=X-Xcr where X is the Flory-Huggins interaction parameter and Xcr is the Flory interaction parameter at the critical point. We found that the characteristic spacing (D) of the lamellar phase is found to accurately follow D =4/3√N at the critical conditions. The chain length (D) dependence as a for the critical strength of interactions was found to obey XcrN =10.495(1+4/N which is consistent with results obtained by complementary approaches found in the literature. We also report on the spacing of the lamellar phase as a function of chain length for systems that are not near the critical point and obtained that the spacings obeyed D α N2/3 to a good approximation for fixed X; whereas for fixed XN, the relation was found to be D α N1/2.The second issue we addressed was the stability of some common mesophases that occur in the transition region between lamellar and hexagonal phases in the block copolymer phase diagram, which. (Abstract shortened by ProQuest).

English

ISBN: 9798708788511Subjects--Topical Terms:

1531702
Membranes.

Thermo-Responsive Block Copolymers: Synthesis, Self-Assembly and Membrane Development /
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100 1 $a Cetintas, Merve Mocan, $e author. $3 3824226
245 1 0 $a Thermo-Responsive Block Copolymers: Synthesis, Self-Assembly and Membrane Development / $c Merve Mocan Cetintas.
264 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2017
300 $a 1 electronic resource (191 pages)
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500 $a Source: Dissertations Abstracts International, Volume: 83-03, Section: B.
500 $a Advisors: Leermakers, F. A. M.; Kamperman, M. M. G. Committee members: Zuilhof, H.; van der Wal, B.; Picchioni, F.; Mendes, E.
502 $b Ph.D. $c Wageningen University and Research $d 2017.
520 $a Block copolymers (BCPs) are attractive materials because of their high tunability and selfassembling ability into regular morphologies in the range of 10-100 nm. They can be used for nanotechnological applications as surfactants, thin films for nanolithography, biomedicine and nanoporous membranes. In this thesis, we aimed to fabricate thermo-responsive iso- and nanoporous membranes that can be used to purify water from nano-sized impurities, also to gain a good understanding on the self-assembly properties of the BCPs.In the introduction of the thesis, given in Chapter 1, we present our scope and aim of the research and introduce the literature about the synthesis and self-assembly of block copolymers. Next, we report the fundamentals of block copolymer membranes including the block copolymer thin films, the SNIPS (self-assembly and non-solvent induced phase separation) process and stimuli-responsive block copolymer membranes.In Chapter 2, we synthesized well-defined polystyrene-poly(N-isopropylacrylamide) (PSPNIPAM) BCPs using reversible-addition-fragmentation-transfer polymerization to produce the desired membranes. Poly(N-isopropylacrylamide) (PNIPAM) is thermoresponsive which exhibits a lower critical solution temperature (LCST) of around 32 °C. This means that at temperatures lower than the LCST, the block is hydrophilic and therefore swollen in aqueous environment and when the temperature is increased above the LCST the block becomes hydrophobic and collapses. When we have the membranes, the pore sizes of the membrane should increase at temperatures above the LCST of PNIPAM, due to collapsing of the PNIPAM chains. The second block of the copolymer, polystyrene (PS), acts as the matrix thereby preventing the block copolymer from dissolving in water and maintaining mechanical stability of the membrane.We optimized the synthesis conditions to obtain BCPs with a high percentage of PS, a high yield and a low polydispersity index (PDI), which are required to produce thermoresponsive iso- and nanoporous membranes with a suitable mechanical stability. According to the literature, the best strategy to synthesize PS-PNIPAM block copolymers was suggested as first synthesizing the PS macro-RAFT agent and extending it with NIPAM monomer. However, following this route we found that when PS was chosen as the majority phase, the obtained yield of this block copolymer was rather low or even zero. Instead, when we synthesized the PNIPAM macro-RAFT agent first and extend it with styrene monomers, we obtained PS-PNIPAM block copolymers with higher yields while maintaining the low PDI values. We used two different RAFT agents to attain block copolymers with various architectures such as AB, ABA and BAB types. We used an AB type block copolymer to produce membranes. The membranes were fabricated using a SNIPS process using a 20 wt% block copolymer solution in N-methyl-2-pyrrolidone (NMP) and tetrahydrofuran (THF) with a volume ratio of 4:6. We found that by increasing the evaporation time from 10 to 80 seconds the membrane surface became more interconnected with smaller pore sizes. Permeability measurements performed from 20 to 50°C showed that the membranes were thermoresponsive and this property was found to be fully reversible when several temperature cycles of 20 and 50°C were applied.To get a deeper insight on the block copolymer self-assembly, we theoretically and experimentally investigated the behavior of block copolymers. Our theoretical work, presented in Chapter 3, employed the self-consistent field method of Scheutjens and Fleer (SF-SCF) which consisted of two parts. As the SF-SCF technique was not yet used for the microphase segregation of block copolymers, we benchmarked the calculations. For this reason, we focused on the chain length dependence of the critical point in the block copolymer phase diagram. In the critical region, we report the scaling behavior of the free energy density and the density differences between the domains as a function of ΔX=X-Xcr where X is the Flory-Huggins interaction parameter and Xcr is the Flory interaction parameter at the critical point. We found that the characteristic spacing (D) of the lamellar phase is found to accurately follow D =4/3√N at the critical conditions. The chain length (D) dependence as a for the critical strength of interactions was found to obey XcrN =10.495(1+4/N which is consistent with results obtained by complementary approaches found in the literature. We also report on the spacing of the lamellar phase as a function of chain length for systems that are not near the critical point and obtained that the spacings obeyed D α N2/3 to a good approximation for fixed X; whereas for fixed XN, the relation was found to be D α N1/2.The second issue we addressed was the stability of some common mesophases that occur in the transition region between lamellar and hexagonal phases in the block copolymer phase diagram, which. (Abstract shortened by ProQuest).
520 $a Blok kopolimerler (BKP'ler) farkli kimyasal ozelliklerdeki iki veya daha fazla polimerin birbirine kovalent bag gibi bir kimyasal bag ile baglanmasindan olusan yapilardir. BKP'ler, bloklarinin kimyasal farkliliklarindan dolayi fazlara ayrismak istemeleri ama yapilarindaki kovalent bagdan dolayi zeytinyagi-su orneginde oldugu gibi makro olcude fazlara ayrisamazlar. Bunun yerine blok kopolimerin blok yuzdesine bagli olarak, 10-100 nm boyutlarinda farkli sekillerde duzenli yapilar olustururlar, buna BKP'nin 'kendiliginden bir araya gelme'si (self-assembly) olayi olarak isimlendirilir. BKP'lerin bu ozelligi ve bloklarin uygulamaya gore istenen sekilde secilebilmesi bu malzemeleri cekici kilmaktadir.Tezin 1. Bolumu'nde verilen Giris kisminda; calismanin kapsami ve amaci belirtilmis, BKP'lerin sentezi ve yukarida bahsedilen kendiliginden bir araya gelme ozelligi hakkinda mevcut literatur sunulmustur. Daha sonra BKP ince filmler ve bir membran uretim yontemi olan 'kendiliginden bir araya gelme ve cokturucu tesirli faz ayrimi' (SNIPS) islemi dahil olmak uzere, BKP membranlar hakkinda temel bilgiler verilmistir.2. Bolum'de, istenen ozelliklerde BKP membranlari elde etmek icin, tersinir eklenmeparcalanma zincir transferi (RAFT) polimerizasyonu ile polistiren-poli(N-izopropil akrilamid) (PS-PNIPAM) BKP'lerin sentezi verilmistir. Poli(N-izopropil akrilamid) (PNIPAM) sicakliga duyarli bir polimer olup 32°C civarinda dusuk kritik cozelti sicakligina (LCST) sahiptir. Bunun anlami, polimer bu sicakliktan daha dusuk sicakliklarda suda cozunebilir haldeyken; bu sicakliktan daha yuksek sicakliklarda su sevmeyen ozellik gostererek suda cozunmez hale gelir. Bu polimerden olusmus membranlarimizin olmasi durumunda, LCST sicakliginin uzerinde PNIPAM zincirlerinin suda cozunmez hale gelerek cokmesinden oturu membran gozeneklerinin genislemesini bekleriz. BKP'nin ikinci blogu olan polistiren (PS), anafaz olarak davranir ve BKP'nin suda cozunmesine mani olmakla beraber membranin mekanik dayaniminin artmasina yardimci olur.RAFT sentez kosullarini; yuksek yuzdeli PS, yuksek verim ve polimerin zincir uzunluklarinin benzer olmasinin ifadesi olan dusuk polidispersite indisi (PDI) elde edecek sekilde ayarladik. Bu sayilan kosullar; sicakliga duyarli, birbiri ile ayni ve nano boyutlarda gozeneklere ve yeterli mekanik dayanima sahip membranlar elde etmek icin gerekli kosullardir. Mevcut literatur, PS-PNIPAM BKP'ler elde etmek icin once PS makro-RAFT ajani sentezini ve daha sonra N-izopropil akrilamid monomeriyle polimer zincirinin uzatilmasini tavsiye etmektedir. Ancak biz yuksek yuzdeli PS iceren BKP'ler sentezlemek icin bu yontemi kullandigimizda, reaksiyon verimini cok dusuk ve hatta bazi durumda sifir olarak elde ettik. Bu sebeple, bu yontem yerine sentezi PNIPAM makro-RAFT ajanindan baslayip stiren monomeriyle polimer zincirini uzatarak gerceklestirdigimizde, daha yuksek verim elde ettigimiz ve PDI degerlerinin de dusuk degerlerde kalmasini sagladigimiz icin bu yontemi tavsiye etmekteyiz. AB, ABA ve BAB tipi BKP'ler elde edebilmek icin iki farkli RAFT ajani kullandik. Membran uretimi icin AB tipi bir BKP kullandik. Membranlar yukarida bahsedilen SNIPS islemi ile agirlikca %20 polimer ve cozucu olarak hacimce 4:6 oraninda N-metil-2-pirolidon (NMP) ve tetrahidrofuran (THF) iceren cozelti kullanarak hazirlanmistir. SNIPS isleminde kullanilan buharlasma suresinin 10 saniyeden 80 saniyeye cikarilmasiyla membran yuzeyinin daha birbirine bagli yapida oldugu ve gozenek boyutlarinin kuculdugu gozlenmistir. 20'den 50°C'ye kadar olan sicakliklarda yapilan gecirgenlik olcumleriyle membranin sicakliga duyarli yapida oldugu ve membrana 20 - 50°C sicaklik devirleri uygulandigi zaman sicakliga duyarli yapinin tam tersinir oldugu gorulmustur.BKP'lerin kendiliginden bir araya gelme ozelligini daha detayli incelemek maksadiyla, teorik ve deneysel calismalar gerceklestirdik. 3. Bolum'de sunulan teorik calismamiz 'Scheutjens ve Fleer'in kendinden tutarli alan kurami' (SF-SCF) olarak isimlendirilen yontemini icermekte olup iki kisma ayrilmaktadir. SF-SCF yontemiyle daha onceden BKP'lerin kendiliginden bir araya gelme olayi incelenmemis oldugu icin oncelikle hesaplamalarimizi dogrulugunu degerlendirmeyi amacladik. Bunun icin oncelikle polimerin zincir uzunlugunun (N) BKP faz diyagraminda bulunan kritik noktaya etkisini inceledik. Kritik bolgede, serbest enerji yogunlugu ile bolgeler arasinda yogunluk farkinin Flory-Huggins etkilesim parametre farkinin (ΔX) birer fonksiyonu oldugunu gosterdik. Flory-Huggins etkilesim parametre farki ΔX = X-Xcr olarak tanimlanmakta olup burada X ve Xcr sirayla belli bir noktadaki ve kritik noktadaki Flory-Huggins etkilesim parametrelerini ifade etmektedir.Kritik kosullarda tabakali (lamellar) fazin karakteristik aralik degerinin (D) zincir uzunluguna fonksiyonunun D =4/3√N oldugunu bulduk. Kritik noktadaki etkilesim gucunun (XcrN) zincir uzunlugu ile olan iliskisi XcrN =10.495(1+4/N bulunmus olup, busonuc daha onceden yayinlanmis literatur sonuclariyla tutarlidir. Ayrica, sabit X degerlerinde kritik noktadan uzak olan bolgelerde tabakali fazin aralik degerinin zincir uzunluguna fonksiyonu D α N2/3, ayni iliski sabit XN degerleri icin D α N1/2. olarak bulunmustur.Calismanin ikinci kisminda tabakali ve altigen fazlarin arasinda bulunan gecis bolgesinde gorulen bazi yaygin arafazlarin kararliliklari incelenmistir. Bu bolge ozellikle ayni boyutta gozenekli membranlar elde etmek icin onem teskil etmektedir. Bu arafazlar; tek gyroid (TG) ve cift gyroid (CG) olarak gyroid'ler, altigen delikli tabakalar (ADT) and cift elmas (CE) olarak sayilabilir. Bu arafazlar XN = 30 gibi orta duzey ayrisma bolgelerinde ve N = 300'de incelenmistir. Yari kararli olan ADT fazinin artan blok orani (f) ile yapisal gelisimi bir fazin digerine nasil gecis yapabildigi hakkinda fikirler vermektedir. Ayrica hala gorus birligine varilamamis olan XN = 120 gibi yuksek. (Abstract shortened by ProQuest).
546 $a English
590 $a School code: 2157
650 4 $a Membranes. $3 1531702
650 4 $a Polymers. $3 535398
650 4 $a Physics. $3 516296
650 4 $a Solvents. $3 620946
650 4 $a Polymerization. $3 560492
650 4 $a Copolymers. $3 1073457
650 4 $a Etching. $2 lcstt $3 3267445
650 4 $a Phase transitions. $3 3560387
650 4 $a Molecular weight. $3 3683783
650 4 $a Pore size. $3 3564182
650 4 $a Thin films. $3 626403
650 4 $a Morphology. $3 591167
650 4 $a Water purification. $3 3699439
650 4 $a Annealing. $2 lcstt $3 3267268
690 $a 0287
690 $a 0605
710 2 $a Wageningen University and Research. $e degree granting institution. $3 3815267
720 1 $a Leermakers, F. A. M. $e degree supervisor.
720 1 $a Kamperman, M. M. G. $e degree supervisor.
773 0 $t Dissertations Abstracts International $g 83-03B.
790 $a 2157
791 $a Ph.D.
792 $a 2017
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