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Self-folding of single chain polymers: towards synthetic biomacromolecule design

Polimer zincirlerinin tekli olarak kendi kendine katlanmasi: sentetik biyomakromolekullerinin diyazn edilmesi dogru yonelim

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  1. Tez No: 768136
  2. Yazar: ÖZCAN ALTINTAŞ
  3. Danışmanlar: PROF. DR. CHRİSTOPHER BARNER-KOWOLLİK
  4. Tez Türü: Doktora
  5. Konular: Polimer Bilim ve Teknolojisi, Polymer Science and Technology
  6. Anahtar Kelimeler: Belirtilmemiş.
  7. Yıl: 2012
  8. Dil: İngilizce
  9. Üniversite: Karlsruher Institut für Technologie
  10. Enstitü: Yurtdışı Enstitü
  11. Ana Bilim Dalı: Polimer Bilim ve Teknolojisi Ana Bilim Dalı
  12. Bilim Dalı: Belirtilmemiş.
  13. Sayfa Sayısı: 259

Özet

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Özet (Çeviri)

Single Chain Folding of Synthetic Polymers via Covalent and Non-Covalent Interactions: State of the ArtThe exquisite design of well-defined polymer chains ? that can subsequently undergo single chain folding driven by covalent and non-covalent interactions ? has been made possible by the control over the composition, molecular weight and molecular weight distribution of synthetic macromolecules offered by several controlled/living radical polymerization (CLRP) techniques including atom transfer radical polymerization (ATRP), nitroxide mediated polymerization (NMP), reversible addition-fragmentation chain transfer (RAFT) polymerization, single electron transfer living radical polymerizations (SET-LRP), activators generated by electron transfer ATRP (AGET-ATRP) or activators regenerated by electron transfer ATRP (ARGET-ATRP). Modular ligation chemistries combine particularly well with these polymerization techniques reactions. The initiators utilized for these polymerizations provide functional groups that are readily converted to the desired functionality for modular ligation chemistries. The preparation and characterization of synthetic polymers mimicking folding elements occurring in natural macromolecules as well as polymeric nanoparticles via single chain folding methods using intramolecular covalent and non-covalent interactions are critically reviewed. The current state of the art in the field of single chain folding indicates that covalent bond driven nanoparticle preparation is well-advanced, while the first encouraging steps towards building reversible single chain folding systems via the use of the mutually orthogonal hydrogen bonding motifs have been made.Single Chain Self-folding of Well-Defined ?,?-Functional Linear Polymers Generated by ATRP and Modular Ligation ChemistryWell-defined ?,?-functional linear poly(styrene) carrying thymine (thy) / diaminopyridine (DAP) (Mn,GPC = 9300, PDI = 1.04) and Hamilton wedge (HW) / cyanuric acid (CA) (Mn,GPC = 8200, PDI = 1.04) bonding motifs are prepared via a combination of controlled/living radical polymerization and copper catalyzed azide alkyne cycloaddition and are subsequently self-assembled as single chains to emulate ? on a simple level ? the self-folding behavior of natural biomacromolecules. Hydrogen nuclear magnetic resonance (1H NMR) in deuterated dichloromethane and dynamic light scattering (DLS) analyses provide evidence for the hydrogen-bonding interactions between the ? -thymine and ? -diaminopyridine as well as ? -cyanuric acid and ? -Hamilton wedge chain ends of the heterotelechelic polymers leading to circular entropy driven single chain self-assembly. The study demonstrates that the choice of NMR solvent is important for obtaining well-resolved NMR spectra of the self-assembled structures. In addition, steric effects on the Hamilton wedge can affect the efficiency of the self-assembly process.Bioinspired Dual Self-Folding of Single Polymer Chains via Reversible Hydrogen BondingWith the aim of preparing synthetic macromolecules that mimic the folding action of natural biomacromolecules, a single synthetic polymer chain containing two distinct and orthogonal hydrogen bonding recognition motifs has been synthesized using an atom transfer radical polymerization and orthogonal ligation strategy. The hydrogen bonding recognition units based on both three-point thymine (Thy) ? diaminopyridine (DAP) and six-point cyanuric acid(CA) ? Hamilton wedge (HW) interactions, induced ? at low concentrations ? a single chain self-folding process. The self-assembly process was monitored ? initially between small molecule models ? by proton nuclear magnetic resonance (1H NMR) spectroscopy, revealing full orthogonality of the two recognition pairs, HW-CA and Thy-DAP. 1H-NMR spectroscopy in deuterated dichloromethane and dynamic as well as static light scattering (DLS and SLS) analyses of the macromolecular self-assembly systems provide unambiguous evidence for the hydrogen-bonding interactions between both the Thy-DAP and CA-HW leading to well-defined dual point single chain self-folding, indicating that more complex single chain self-assemblies based on synthetic polymers should able to mimic ? on a simplified level ? the folding actions of natural biomacromolecules. The reversibility of the self-folding action depends on temperature as confirmed via 1H-NMR spectroscopy in [D2]tetrachloroethane.Star and Miktoarm Star Block (Co)polymers via Self-Assembly of ATRP Generated Polymer Segments Featuring Hamilton Wedge and Cyanuric Acid Binding MotifsHamilton Wedge (HW) end-functionalized poly(styrene) (PS-HW, Mn = 5400 g mol-1, PDI = 1.06), HW mid-chain functionalized poly(styrene) (PS-HW-PS, Mn = 4600 g mol-1, PDI = 1.04), cyanuric acid (CA) end-functionalized poly(styrene) (PS-CA, Mn = 3700 g mol-1, PDI = 1.04) and CA end-functionalized poly(methyl methacrylate) (PMMA-CA, Mn = 8500 g mol-1, PDI = 1.13) precursors were successfully synthesized via a combination of atom transfer radical polymerization (ATRP) and copper catalyzed azide?alkyne cycloaddition (CuAAC). The precursor polymers were characterized via size exclusion chromatography (SEC) and 1H-NMR with respect to both molecular weight and structure. Supramolecular homopolymer (PS-HW ? PS-CA), block copolymer (PS-HW ? PMMA-CA), star polymer (PS-HW-PS ? PS-CA) as well asmiktoarm star polymer (PS-HW-PS ? PMMA-CA) was formed in solution in high yields at ambient temperature (association close to 89% for PS-HW ? PS-CA, 90% for PS-HW-PS ? PS-CA and 98% for PS-HW-PS ? PMMA-CA) via H-bonding between the orthogonal recognition units, HW and CA. The formation of supramolecular polymers was confirmed via 1H NMR at ambient temperature in deuterated methylene chloride (CD2Cl2) solution.Combining Modular Ligation and Supramolecular Self-Assembly for the Construction of Star-Shaped MacromoleculesA well-defined random copolymer of styrene (S) and chloromethylstyrene (CMS) featuring lateral chlorine moieties (on 6% of all repeat units) with an alkyne terminal group is prepared by the nitroxide-mediated radical polymerization (NMP) process (P(S-co-CMS), Mn = 5500 Da, PDI = 1.13). The choromethyl groups of CMS are subsequently converted to Hamilton wedge (HW) entities via an etherification with hydroxyl functional HW (P(S-co-HWS), Mn = 6200 Da, PDI = 1.13). The P(S-co-HWS) precursor polymer is subsequently ligated with tetrakis(4-azidophenyl)methane to give HW-functional star-shaped macromolecules via copper catalyzed azide-alkyne cycloaddition (CuAAC) ((PS-co-HWS)4, Mn = 25100 Da, PDI = 1.08). Supramolecular grafted star-shaped copolymers have then been prepared through self-assembly between the HW functionalized 4-arm star macromolecules (PS-co-HW)4 and cyanuric acid (CA) end-functionalized poly(styrene) (PS-CA, Mn = 3700 Da, PDI = 1.04), CA end-functionalized poly(methyl methacrylate) (PMMA-CA, Mn = 8500 Da, PDI = 1.13) and CA end-functionalized polyethylene glycol (PEG-CA, Mn = 1700 Da, PDI = 1.05). The star self-assembly in solution is monitored by proton nuclear magnetic resonance (1H NMR) spectroscopyas well as dynamic and static light scattering (DLS and SLS) analyses, demonstrating an efficient formation of self-assembled star-shaped polymers.

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