Download or read book Synthesis of Stimuli responsive Polymers Via Nitroxide Mediated Polymerization and Characterization in Aqueous and Ionic Liquid Solutions written by Chi Zhang and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Stimuli-responsive polymers have been touted as "smart" due to their fast and reversible responses to environmental changes. It is imperative for these polymers to have well-defined structures so that their performance can be consistent and predictable. In order to achieve this, nitroxide mediated polymerization (NMP) was employed as the synthesis technique for the microstructured polymers that form the core of the investigations presented in this thesis. As one of the main controlled radical polymerization techniques, NMP stands out for its simplicity in both required ingredients and purification procedures. Many known stimuli-responsive polymers are poly(methacrylates). However, homopolymerization of methacrylates has been challenging for NMP mainly due to the large equilibrium constant that resulted in high concentration of active radicals and thus excessive irreversible terminations. By using a small amount of "controlling co-monomer" such as styrene, copolymerizations with methacrylate-rich feeds can be controlled using the commercially available alkoxyamine initiator BlocBuilderTM via NMP, featuring linear increases in number average molecular weight versus conversion, and narrow molecular weight distribution.In this thesis, two methacrylates, namely 2-(dimethylamino)ethyl methacrylate (DMAEMA) and benzyl methacrylate (BzMA), whose homopolymers exhibit LCST-type phase separation behaviours in aqueous and ionic liquid (IL) solutions, respectively, were copolymerized with various controlling co-monomers by NMP to demonstrate the versatility of NMP in tuning thermo-responsive properties. For both methacrylates, styrene was initially used as the controlling co-monomer to obtain copolymers with relatively narrow molecular weight distribution and ability to extend chains to form block copolymers when reinitiated with a fresh batch of monomer. 2-Vinylpyridine (2VP) was then chosen to copolymerize with DMAEMA for its lower hydrophobicity compared to styrene and pH-sensitivity, where about 2 - 5 mol% 2VP was shown sufficient to obtain well-defined DMAEMA/2VP copolymers. The detailed phase behaviour characterization of these DMAEMA-rich copolymers in aqueous solutions revealed the effects of important factors such as pH, copolymer composition, solution concentration and polymer microstructure, on the tuning of transition temperatures.For BzMA, 9-(4-vinylbenzyl)-9H-carbazole (VBK) was used as an alternative controlling co-monomer. Controlled and pseudo-"living" copolymerizations were achieved with as little as 2 mol% VBK in the feed, demonstrating significant improvement compared to the BzMA/styrene system. The incorporation of fluorescent VBK resulted in 5-fold fluorescence enhancement during the phase separation of BzMA/VBK copolymers from IL [C2mim][NTf2]. The enhancement resulted from heightened efficiency of the fluorescence resonance energy transfer (FRET) between BzMA and VBK during aggregation. However, the solvatophobicity of VBK also significantly reduced the solubility of BzMA/VBK copolymers in the IL and rendered the phase separation irreversible. Further investigation on the effects of solvatophilicity and chain mobility on phase separation and reversibility in ILs was carried out by incorporating varying amounts of solvatophilic co-monomer, namely methyl methacrylate (MMA) and oligo(ethylene glycol) methacrylate (OEGMA), yielding BzMA/MMA/VBK and BzMA/OEGMA/VBK terpolymers. It was found that molecular weight, glass transition temperature, and solution concentration all played important roles on phase separation temperature but sufficiently high solvatophilicity (quantified by the concentration of solvatophilic group) was essential to facilitate the re-dissolution process after phase separation. " --
Download or read book Synthesis and Characterization of Stimuli responsive Polymers with Aqueous Atom Transfer Radical Polymerization written by Collin N. Britten and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis of Amino Functional Monomers Via Controlled Radical Polymerization written by Xeniya Savelyeva and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Controlled radical polymerization (CRP) techniques has allowed the synthesis of numerous polymeric materials with comparable control to that of true "living" techniques without the need for stringent manipulation techniques. The control over chain length, dispersity and composition is desirable in many fields, such as stimuli-responsive (temperature or pH) drug carriers. These thermoresponsive polymers in aqueous media are often characterized by lower critical solution temperature (LCST) behavior, where the polymer becomes insoluble with temperature increases. The LCST can be tuned by the structural features of the constituent monomer, molecular weight, molecular weight distribution and copolymerization with other monomers. Narrow molecular weight distribution is the key factor determining the sharpness needed for determining the LCST, which is often exemplified by the cloud point temperature (CPT). Using CRP techniques, specifically nitroxide mediated polymerization (NMP), with an alkoxyamine unimolecular initiator, 2-([tert-butyl[1-(diethoxyphosphoryl)-2,2-dimethylpropyl]amino]oxy)-2-methylpropanoic acid (BlocBuilder) and an additional free nitroxide (SG1), the effect of controlling comonomer (9-(4-vinylbenzyl)-9H-carbazole (VBK)) on polymerization kinetics of N-(2-methacryloyloxyethyl) pyrrolidone (MAEPYR) and the effect of final copolymer composition on CPT was studied. Adding at least 5 mol% VBK, the dispersity Đ of the poly(MAEPYR-stat-VBK) copolymers was below 1.4. The CPT decreased from 59.0 °C to 49.7 °C with addition of only 1 mol% of VBK in the copolymer, and it can be further fine-tuned by changing the solution concentration and the heating rate. Another CRP technique, reversible addition fragmentation chain-transfer polymerization (RAFT), was applied to homopolymerization of N-(3-methoxypropyl) acrylamide (MPAM) to yield well-defined polymers (with (M_n)− = 14.3 - 25.2 kg mol-1 and low Đ ~ 1.17 - 1.47) needed for precise determination of CPT. Thermoresponsive behaviour of poly(MPAM) in aqueous media revealed CPTs between 73 and 92 °C, unlike other literature reports where the polymers, synthesized by conventional radical polymerization, showed conflicting results regarding their LCST" --
Download or read book Nitroxide Mediated Polymerization written by Didier Gigmes and published by Royal Society of Chemistry. This book was released on 2016 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first book dedicated to nitroxide-mediated polymerization and covers the history and development of NMP, as well as current techniques of academic and industrial interest.
Download or read book Preparation of Telechelic Polymers Via Nitroxide Mediated Polymerization written by Gregory J. O'Bryan and published by . This book was released on 2007 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Application of Ionic Liquids in Drug Delivery written by Masahiro Goto and published by Springer Nature. This book was released on 2021-08-27 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents recent advances in the use of ionic liquids in medicine and pharmaceutics with particular emphasis on addressing critical pharmaceutical challenges, including the low solubility, polymorphism, and bioavailability of drugs. It also provides insights into the development of the biologically functionalized ionic liquids suitable for medical and pharmaceutical applications. Ionic liquids have been used as potential solvents or materials in the fields of pharmaceutical drug delivery and formulations because of their unique and tunable physicochemical and biological properties. Readers find explanations of the diverse approaches to the application of ionic liquids in drug solubility, active pharmaceutical ingredient (API) formulation, and drug delivery systems, such as topical, transdermal, and oral delivery, with particular emphasis on recent developments. Particular attention is given to the development of ionic liquid-assisted effective drug delivery techniques for sparingly soluble or insoluble drug molecules. This book also discusses the biological activities of ionic liquids for possible applications in drug formulation and drug delivery systems. Scientists in disciplines such as chemistry, biology, and pharmaceutics find this book instructive and informative for developing ionic liquid-based drug formulations or drug delivery systems.
Download or read book Alkoxyamine Initiators for Nitroxide Mediated Radical Polymerization written by Jean K. Ruehl and published by . This book was released on 2008 with total page 990 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of Self assembling Polymers Using Hydrogen Bonding Or Hydrophobic Effect written by Xinjun Yu and published by . This book was released on 2015 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Self Healing Polymers written by Wolfgang H. Binder and published by John Wiley & Sons. This book was released on 2013-03-29 with total page 638 pages. Available in PDF, EPUB and Kindle. Book excerpt: Self-healing is a well-known phenomenon in nature: a broken bone merges after some time and if skin is damaged, the wound will stop bleeding and heals again. This concept can be mimicked in order to create polymeric materials with the ability to regenerate after they have suffered degradation or wear. Already realized applications are used in aerospace engineering, and current research in this fascinating field shows how different self-healing mechanisms proven successful by nature can be adapted to produce even more versatile materials. The book combines the knowledge of an international panel of experts in the field and provides the reader with chemical and physical concepts for self-healing polymers, including aspects of biomimetic processes of healing in nature. It shows how to design self-healing polymers and explains the dynamics in these systems. Different self-healing concepts such as encapsulated systems and supramolecular systems are detailed. Chapters on analysis and friction detection in self-healing polymers and on applications round off the book.
Download or read book Interfacial Synthesis Polymer applications and technology written by Frank Millich and published by . This book was released on 1977 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of Polymers Incorporating N alkyl Urea peptoid Sequences written by Xiaoping Chen and published by . This book was released on 2013 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation is mainly based on the works of synthesis and characterization of polymer/N-alkyl urea peptoid hybrid materials. Polymers were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization using thrithiocarbonate and dithiocarbonate chain transfer agents in controlled manner. Poly(N-alkyl urea peptoid) was synthesized via step growth polymerization using symmetric diamine and diisocyanate. N-Alkyl urea peptoid sequences up to sixmer were synthesized through three steps repetition cycles in good yields. Several different hybrid polymeric materials were explored combining the three different material synthetic strategies including polymer conjugates shown in chapter 2, molecular brushes shown in chapter 3, water soluble A-B-A triblock copolymer shown in chapter 4. Firstly, two well-defined statistical copolymers poly(styrene-co-3-azidopropyl methacrylate) and poly(3-O-methacryloyl-1,2:5,6-di-O-isopropylidene-[subscript D]-glucofuranose -co-AzPMA) were synthesized by RAFT. An exemplary N-alkyl urea peptoid trimer was synthesized and conjugated to the two copolymers through the 'click' reaction of the azide pendent group of polymers with the complilanry alkene group at N-alkyl urea peptoid. The polymer conjugates were subjected to further post-modification to generated fluorescent conjugates or water soluble materials. Following the explore of conjugation, N-alkyl urea peptoid was used as comonomer to synthesize linear poly(N-alkyl urea peptoid). The RAFT agent was introduced onto the linear polymer generated by step growth polymerization once again through 'click' reaction. Sequentially, styrene and tert-butyl acrylate was grown from RAFT agents sites that fused onto the poly(N-alkyl urea peptoid) backbone to make block copolymer arms. Upon removal of the tert-butyl groups, the molecular brushes were observed to generate micelles in aqueous solution. The self-assembly N-alkyl urea peptoid was then investigated and conjugated to water soluble polymer poly(ethylene glycol) to produce a A-B-A block copolymer that self-assembled into ribbons in aqueous solution. The final two part of dissertation was about gelling materials studies starting with presenting a synthesis strategy for low molecular weight organogelators (LMOG) using the ureidopyrimidinone (UPy) group functioned N-alkyl urea peptoid. The surprising observation of gelation in DMSO led to extensive investigation of the gelification mechanism studies. Based on the lessons of LMOG, the copolymerization of different T[subscript g] monomers with quadruple hydrogen bonding containing methacrylate was demonstrated suitable to produce polymeric organogelators in the final chapter.
Download or read book Smart Polymers and their Applications written by Maria Rosa Aguilar and published by Elsevier. This book was released on 2014-02-19 with total page 587 pages. Available in PDF, EPUB and Kindle. Book excerpt: Smart polymers are polymers that respond to different stimuli or changes in the environment. Smart Polymers and their Applications reviews the types, synthesis, properties, and applications of smart polymers. Chapters in part one focus on types of polymers, including temperature-, pH-, photo-, and enzyme-responsive polymers. Shape memory polymers, smart polymer hydrogels, and self-healing polymer systems are also explored. Part two highlights applications of smart polymers, including smart instructive polymer substrates for tissue engineering; smart polymer nanocarriers for drug delivery; the use of smart polymers in medical devices for minimally invasive surgery, diagnosis, and other applications; and smart polymers for bioseparation and other biotechnology applications. Further chapters discuss the use of smart polymers for textile and packaging applications, and for optical data storage. Smart Polymers and their Applications is a technical resource for chemists, chemical engineers, mechanical engineers, and other professionals in the polymer industry; manufacturers in such sectors as medical, automotive, and aerospace engineering; and academic researchers in polymer science. Reviews the different types of smart polymer, discussing their properties, structure, design, and characterization Reviews applications of smart polymers in such areas as biomedical engineering, textiles, and food packaging
Download or read book Synthesis and Characterization of Temperature and Light responsive Polymers and Block Copolymers written by Florian D. Jochum and published by . This book was released on 2010 with total page 123 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mambo mortale written by Landesstelle Jugendschutz and published by . This book was released on 1990 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of Nano sized Polymer Particles Using Differential Microemulsion Polymerization written by Guangwei He and published by . This book was released on 2006 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Polymer Functionalized Graphene written by Arun Kumar Nandi and published by Royal Society of Chemistry. This book was released on 2021-06-18 with total page 457 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is an immense variety of research on polymer functionalized graphene (PFG). Functionalization of graphene is necessary for improvement of the compatibility with polymers. Applications of these graphene polymer hybrids include in chemical and biological sensing, photovoltaic devices, supercapacitors and batteries, dielectric materials and drug/gene delivery vehicles. This book will shed light on the synthesis, properties and applications of these new materials, covering two methods (covalent and noncovalent) for producing polymer functionalized graphene. Chapters cover physical, optical, mechanical and electronic properties, applications of polymer functionalized graphene in energy harvesting and storage, and uses in biomedicine and bioengineering. Written by an expert in the field, Polymer Functionalized Graphene will be of interest to graduate students and researchers in polymer chemistry and nanoscience.
Download or read book Polymer Capsules written by Ye Liu and published by CRC Press. This book was released on 2019-05-10 with total page 385 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymers are one of the most versatile and important materials used for capsule preparation despite various others available. Suitably formulated capsules can securely protect ingredients, deliver them to targeted sites, and release them expeditiously, improving functions and minimizing adverse effects. New polymers are constantly being explored to develop more efficient capsules as they are routinely used in pharmaceuticals, consumer healthcare products, nutrients, and food. This book focuses on the current state of the art of polymer-based capsules and delivery systems. It describes the formulation processes of capsules developed from redox-responsive polymers and polymer-functionalized carbon nanotubes, in addition to shedding light on coacervation of polymers for encapsulation. It reviews different active ingredients that can be used with polymer capsules in various products, encapsulation of essential oils using such capsules, and development of polymer capsules of cells and bacteriophages.
