Synthesis And Characterization Of Self Assembled Diblock Copolymers Containing Azo Pendant Groups
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Synthesis And Characterization Of Self Assembled Diblock Copolymers Containing Azo Pendant Groups
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Author : 安家幸
language : en
Publisher:
Release Date : 2008
Synthesis And Characterization Of Self Assembled Diblock Copolymers Containing Azo Pendant Groups written by 安家幸 and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with categories.
Synthesis Characterization And Self Assembly Of Amphiphilic Block Copolymers
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Author : Xiaojun Wang
language : en
Publisher:
Release Date : 2012
Synthesis Characterization And Self Assembly Of Amphiphilic Block Copolymers written by Xiaojun Wang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
This dissertation presents a review on state-of-the-art research of well-defined charged block copolymers, including synthesis, characterization, bulk morphology and self-assembly in aqueous solution of amphiphilic block polyelectrolytes. In Chapter 1, as a general introduction, experimental observations and theoretical calculations devoted towards understanding morphological behavior in charged block copolymer systems are reviewed along with some of the new emerging research directions. Further investigation of charged systems is urged in order to fully understand their morphological behavior and to directly target structures for the tremendous potential in technological applications. Following this background, in Chapters 2, 3, 4 and 5 are presented the design and synthesis of a series of well-defined block copolymers composed of charged and neutral block copolymers with full characterization: sulfonated polystyrene-b-fluorinated polyisoprene (sPS-b-fPI) and polystyrene-b-sulfonated poly(1,3-cyclohexadiene) (PS-b-sPCHD). Their bulk morphological behaviors in melts and self-assembly of sPS-b-fPI, PS-b-sPCHD in water were investigated. Some unique behaviors of sPS-b-fPI were discovered. The mechanisms for formation of novel nanostructures in aqueous solution are discussed in details in Chapter 4. Spherical and vesicular structures were formed from strong electrolyte block copolymers, e.g. PS-bsPCHD. Detailed light scattering and transmission electron microscopy were applied to characterize these structures. The abnormal formation of vesicles as well as microstructure effects on self-assembly is discussed in Chapter 5. In Chapter 6, we describe the successful synthesis of a well-defined acid-based block copolymers containing polyisoprene while maintaining the integrity of the functionality (double bonds) of polyisoprene. A general purification method is also presented in order to remove homo polyisoprene, polystyrene, and PS-b-PI in the di-, and tri-block copolymers. The self-assembly of PS-b-PI-b-PAA triblock terpolymers was studied in order to form multicompartmental structures in aqueous environments. In the last Chapter 7, detailed synthesis and characterization of a novel conjugate: poly(L-leucine) grafted hyaluronan (HA) (HA-g-PLeu) are presented. This work describes a new method to synthesize HA-g-PLeu via a "grafting onto" strategy. Due to the amphiphilic nature of this graft copolymers, a "local network" formed by self-assembly which was characterized by atomic force microscopy and light scattering. The secondary structure of the polypeptide was revealed by circular dichroism.
Synthesis And Characterization Of Smart Block Copolymers For Biomineralization And Biomedical Applications
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Author :
language : en
Publisher:
Release Date : 2008
Synthesis And Characterization Of Smart Block Copolymers For Biomineralization And Biomedical Applications written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with categories.
Self-assembly is a powerful tool in forming structures with nanoscale dimensions. Self-assembly of macromolecules provides an efficient and rapid pathway for the formation of structures from the nanometer to micrometer range that are difficult, if not impossible to obtain by conventional lithographic techniques [1]. Depending on the morphologies obtained (size, shape, periodicity, etc.) these self-assembled systems have already been applied or shown to be useful for a number of applications in nanotechnology [2], biomineralization [3, 4], drug delivery [5, 6] and gene therapy [7]. In this respect, amphiphilic block copolymers that self-organize in solution have been found to be very versatile [1]. In recent years, polymer-micellar systems have been designed that are adaptable to their environment and able to respond in a controlled manner to external stimuli. In short, synthesis of 'nanoscale objects' that exhibit 'stimulus-responsive' properties is a topic gathering momentum, because their behavior is reminiscent of that exhibited by proteins [8]. By integrating environmentally sensitive homopolymers into amphiphilic block copolymers, smart block copolymers with self assembled supramolecular structures that exhibit stimuli or environmentally responsive properties can be obtained [1]. Several synthetic polymers are known to have environmentally responsive properties. Changes in the physical, chemical or biochemical environment of these polymers results in modulation of the solubility or chain conformation of the polymer [9]. There are many common schemes of engineering stimuli responsive properties into materials [8, 9]. Polymers exhibiting lower critical solution temperature (LCST) are soluble in solvent below a specific temperature and phase separate from solvent above that temperature while polymers exhibiting upper critical solution temperatures (UCST) phase separate below a certain temperature. The solubility of polymers with ionizable moieties depends on the pH of the solution. Polymers with polyzwitterions, anions and cations have been shown to exhibit pH responsive self assembly. Other stimuli responsive polymers include glucose sensitive polymers, calcium ion-sensitive polymers and so on. Progress in living radical polymerization (LRP) methods [10] has made it possible for the facile synthesis of these block copolymer systems with controlled molecular weights and well defined architectures. The overall theme of this work is to develop novel smart block copolymers for biomineralization and biomedical applications. Synthesis and characterization of self-assembling thermoreversible ionic block copolymers as templates in biomimetic nanocomposite synthesis using a bottom-up approach is a novel contribution in this respect. Further, we have extended these families of copolymers to include block copolymer-peptide conjugates to enhance biological specificity. Future directions on this work will focus on enhancing the polymer templating properties for biomineralization by expanding the family of block copolymers with organic polypeptides and biological polypeptide scaffolds as well as a detailed understanding of the polymer-inorganic nanocomposites at the molecular level using small angle scattering analysis. Glucose responsive polymer hydrogels for drug delivery, polymer-ligand conjugates for non-viral therapy and thermoresponsive injectable photocrosslinkable hydrogels for posttraumatic arthritis cartilage healing are other applications of these novel copolymers synthesized in our work.
Synthesis And Characterization Of Stimuli Responsive Block Copolymers Self Assembly Behavior And Applications
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Author : Michael Duane Determan
language : en
Publisher:
Release Date : 2006
Synthesis And Characterization Of Stimuli Responsive Block Copolymers Self Assembly Behavior And Applications written by Michael Duane Determan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with categories.
Water-soluble stimuli responsive block copolymers are a rapidly emerging class of materials with great potential in biomedical and technological applications. In this work a novel class of pentablock copolymers are synthesized via atom transfer radical polymerization techniques and their stimuli-responsive self-assembly properties are characterized. Aqueous solutions of these materials are observed to form micelles and hydrogels in response to changes in both temperature and pH. Cryogenic transmission electron microscopy (cryo-TEM) and small angle neutron and X-ray scattering (SANS and SAXS) techniques are used to investigate the nanoscale structures formed by these pentablock copolymers in solution. The gel structure and mechanical properties are investigated with SANS and rheological techniques. The multi-responsive properties of these materials are utilized to formulate a stimuli responsive drug delivery formulation that exhibits thermoreversible gelation and pH dependent release rate of model drugs.
Mambo Mortale
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Author : Landesstelle Jugendschutz
language : en
Publisher:
Release Date : 1990
Mambo Mortale written by Landesstelle Jugendschutz and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1990 with categories.
Synthesis And Characterization Of Self Assembling Polymers Using Hydrogen Bonding Or Hydrophobic Effect
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Author : Xinjun Yu
language : en
Publisher:
Release Date : 2015
Synthesis And Characterization Of Self Assembling Polymers Using Hydrogen Bonding Or Hydrophobic Effect written by Xinjun Yu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
This dissertation is mainly based on the works of synthesis and characterization of self-assembling polymers using hydrogen bonding or hydrophobic interactions. Firstly, N-alkyl urea peptoid oligomer was synthesized as backbone of supramolecular polymers through three step repetition cycles with high yield. One N-alkyl urea peptoid precursor was explored to simplify the synthetic process. 4 different functional groups were converted from one precursor. Then 2-ureido-4[1H]-pyrimidinone (UPy) group which is a quadruple hydrogen bonding system was incorporated to N-alkyl urea peptoid oligomers to generate supramolecules. With the experience of UPy unit, we further explored UPy containing monomer to make organogelators. Three different monomers with different Tg values were copolymerized using reversible addition-fragmentation chain-transfer (RAFT) polymerization. Organogels were afforded in both chloroform and dichlorobenzene. Critical gelation concentration and mechanic properties of organogels were examined. Cooperating another novel monomer containing pyrene unit to the above copolymers, fluorescent organogels were achieved which were suitable for potential up-conversion applications. In addition to pyrene, anthracene is another molecule which shows great up-conversion property. A series of Poly[(9-anthrylmethyl methacrylate)-co-(methyl methacrylate)] (Poly(AnMMA-co-MMA)) with different AnMMA ratios were synthesized via RAFT polymerization, resulting in tunable inter-chromophore distances. These polymers can serve as emitters, with PtOEP as sensitizer, in triplet-triplet annihilation up-conversion (TTA-UC) systems. TTA-UC intensity of the Poly(AnMMA-co-MMA)/PtOEP mixtures displays interesting dependence on the AnMMA ratio in the polymer. Interactions between chromophores on the same polymer chain play the key role in affecting the TTA-UC intensity in these systems. It is critical to minimize intra-chain chromophore quenching in order to achieve high UC intensity. Hydrophobic effect was used to obtain a hybrid photosensitizer. By integrating amphiphilic block copolymer poly(N-isopropylacrylamide-b-styrene) (PNIPAAm-b-styrene) stabilized silver nanoparticles (Ag NPs) with hematoporphyrin (HP), HP was trapped by polystyrene block through hydrophobic effects. Hydrophilic block can increase the solubility of this photosensitizer in aqueous solution. This hybrid photosensitizer was demonstrated to enhance singlet oxygen production. Finally, a self-immolative polymer was made with a kinetically stable polymer backbone, whose chain end can respond to external stimulus by triggering a head-to-tail depolymerizaiton. Electrospining was used to fabricate nano-scale fibers which can be utilized in potential drug delivery system.
Synthesis And Characterization Of Pdms Based Block Copolymers Toward Sub 10nm Nanopatterning
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Author : Yingdong Luo
language : en
Publisher:
Release Date : 2015
Synthesis And Characterization Of Pdms Based Block Copolymers Toward Sub 10nm Nanopatterning written by Yingdong Luo and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
Block copolymer self-assembly has been used as nanopatterning towards applications of lithography for decades. For the purpose of smaller, faster and cheaper transistor developments, block copolymers with high Flory-Huggins parameter and better etching contrast need to be further developed. PDMS based block copolymers are of the most interest among all candidates. I synthesized a library of well defined PDMS-b-PMMA, PDMS-b-PS and PDMS-b-PEO through "click" chemistry. The Flory-Huggins interaction parameters of these block copolymers are characterized much higher than conventional block copolymers as expected. Therefore, sub-10 nm domain periods are achieved by these materials in bulk. Significantly, long range ordered nanoline and nanodot patterns have been produced by PDMS-b-PMMA. Furthermore, a small molecule (L)-tartaric acid used as a hydrogen bonding donor was proved to efficiently suppress the crystallinity of PEO and significantly enhance the self-assembly behavior. Finally, the triazole moiety in the middle of the block copolymer which synthesized by "click" chemistry was functionalized to produce an ionic junction block copolymer. The electrostatic interactions before the opposite charges act as an extra enthalpy to help the self-assembly. Therefore, order disorder transition temperature of the block copolymer was dramatically increased.
Molecular Design Synthesis Characterization And Processing Of Liquid Crystalline Diblock Copolymers
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Author : Guoping Mao
language : en
Publisher:
Release Date : 1997
Molecular Design Synthesis Characterization And Processing Of Liquid Crystalline Diblock Copolymers written by Guoping Mao and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1997 with categories.
Synthesis Morphologies And Applications Of Polyoxometalate Containing Diblock Copolymers
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Author : Sanjiban Chakraborty
language : en
Publisher:
Release Date : 2011
Synthesis Morphologies And Applications Of Polyoxometalate Containing Diblock Copolymers written by Sanjiban Chakraborty and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Block copolymers categories.
Block copolymers by virtue of their ability to self assemble and microphaseseparation due to the contrast in chemical and physical properties of the covalently linked blocks constitute the essential building blocks towards various nano or micro sized architectures. Polyoxometalates (POM), on the other hand, being an interesting class of metal-oxygen nanometer-sized anionic clusters, are regarded highly due to their excellent electron accepting capability. Combining POM clusters with diblock copolymers can lead to a fascinating class of hybrid materials where the POM cluster not only affect the selfassembly process of various diblock copolymers but also brings its unique electronic properties into the hybrid system. Herein we report the detailed synthesis and characterizations of two hybrid coil-coil diblock copolymers along with two hybrid rodcoil diblock copolymers through polymerization-hybridization approach. The coil-coil diblocks were synthesized via atom transfer radial polymerization (ATRP) of styryl-type monomers and 4-vinylpyridine in sequence. For rod-coil diblock copolymers, the coil block was synthesized through ATRP, followed by the conversion of the terminal bromide to an azide. Ethynyl terminated poly (p-phenylenevinylene) (PPV) and poly (3-hexylthiophene) (P3HT) were prepared separately as the rod blocks. The rod block and the coil block were connected through click chemistry to yield rod-coil diblock copolymers. After removing the phthalimide protecting groups to regenerate aryl amines, POM clusters were finally linked to the coil block of all diblock copolymers to yield the targeted hybrid diblock copolymers. The covalent cluster attachment was confirmed by UV-Vis spectroscopy, FTIR and cyclovoltammetry measurements. The structures, solution and film optical properties, self-assembled morphologies and solar cell performances of these hybrids have been studied. It has been found that solar cell devices based on hybrid P3HT exhibited rather poor performances. Fluorescence dynamic studies indicate that the photoinduced electron transfer process from the rod block to pendant POMs is quite inefficient which may account for the poor device performance. Though the self-assembly process of these hybrid diblock copolymers and the preliminary morphologies has been demonstrated, detailed and systematic study of morphological control requires further extensive research.
Synthesis And Characterization Of Self Assembling Low Molecular Weight Copolymers For Bioengineering Applications
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Author :
language : en
Publisher:
Release Date : 2013
Synthesis And Characterization Of Self Assembling Low Molecular Weight Copolymers For Bioengineering Applications written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.