Living Controlled Polymerization Conducted In Aqueous Based Systems
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Living Controlled Polymerization Conducted In Aqueous Based Systems
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Author : Ryan W. Simms
language : en
Publisher:
Release Date : 2007
Living Controlled Polymerization Conducted In Aqueous Based Systems written by Ryan W. Simms and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
In the last decade processes known as living/controlled radical polymerizations (L/CRP) have been developed which permit the synthesis of high-value specialty polymers. Currently, the three processes that have demonstrated the most potential are: reverse addition fragmentation chain transfer polymerization (RAFT), atom transfer radical polymerization (ATRP) and stable free radical polymerization (SFRP). While each process has their strengths and weaknesses with regard to specific polymers and architecture, the viability of these systems to industrial scale production all lie in the ability to perform the polymerization in a water based system because of process, environmental and economic advantages. The most effective method of controlling the polymerization of vinyl acetate in bulk has been RAFT. We have developed a miniemulsion RAFT polymerization using the xanthate methyl (ethoxycarbonothioyl)sulfanyl acetate. The miniemulsion is stabilized with 3 wt% sodium lauryl sulfate, initiated with the azo-based water-soluble VA-060. The main focus of this research was adapting ATRP to a miniemulsion system. It was determined that ionic surfactants can be successfully employed in emulsion-based ATRP. The cationic surfactant cetyltrimethylammonium bromide provides excellent stability of the latex over a range of surfactant loadings (allowing the particle size to be easily manipulated), at temperatures up to 90 C, for a wide variety of ATRP formulations. A new method of initiation was developed for reverse ATRP, using the redox pair hydrogen peroxide/ascorbic acid. This nearly eliminated the induction period at the start of the polymerization, increased the polymerization rate 5 fold and, surprisingly, enabled the formation of well-controlled polymers with a number-average molecular (Mn) weight approaching 1 million (typically ATRP is limited to ~200 000). The ability to control the particle size and the number of polymer chains (through the target Mn) over a wide range of values allowed us to determine that ATRP is influenced by compartmentalization effects. The knowledge gained from our work in L/CRP was used to develop the surfactant-free SFRP of styrene. A multi-stage approach was adopted starting from dilute styrene/water solutions to favor the formation of the alkoxyamine and short chain SG1-oligomers (stage one) before the addition of the majority of the styrene (stage two).
Stable Free Radical Polymerization Conducted In Emulsion Polymerization Systems
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Author :
language : en
Publisher:
Release Date : 2002
Stable Free Radical Polymerization Conducted In Emulsion Polymerization Systems written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with categories.
Free radical polymerization is the most common polymerization technique that is used for the manufacturing of polymers, due to the ease of the polymerization initiation, wide latitude of the material design for a large variety of monomers, and the excellent process robustness for commercial production. In the 1990's, research activities for the precise control of radical polymerization process resulted in the discovery of 'Living Radical Polymerization'. The discoveries opened the door for the next generation of radical polymerizations. Extensive research has been conducted to understand the mechanisms and kinetics for numerous practical applications, particularly for polymerization in bulk and solution systems. However, despite the interest of industry, the mechanistic understanding in aqueous dispersed systems such as emulsion and miniemulsion polymerization is far behind the aforementioned two systems. There are still major challenges from the production viewpoint. One reason for the poor understanding is the complexity of the heterogeneous system, which includes multiple reaction phases that are accompanied by the segregation and transfer of the reaction species among different phases. The purpose of this research was to investigate living radical polymerization or "Stable Free Radical Polymerization" (SFRP) in aqueous dispersed systems to obtain better mechanistic understanding of how the heterogeneous nature of the system interacts with the novel living radical chemistry. The theoretical and experimental feasibility of the SFRP emulsion process were studied in this research, in particular, focusing on the compartmentalization effect. Particle size influence on the polymerization kinetics and the polymer livingness was experimentally confirmed, and compared to bulk polymerization. In addition, a comprehensive mathematical model including all major chemical and physical events was developed to further our mechanistic understanding. Based on the results from the.
Emulsion Based Free Radical Retrograde Precipitation Polymerization
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Author : Gerard Caneba
language : en
Publisher: Springer Science & Business Media
Release Date : 2011-07-02
Emulsion Based Free Radical Retrograde Precipitation Polymerization written by Gerard Caneba and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-07-02 with Technology & Engineering categories.
This monograph is a follow-up material to the first FRRPP book by Gerard Caneba in 2009. It includes additional conceptual results, implementation of the FRRPP process in emulsion media to produce various block copolymers, and other FRRPP-related supplementary topics. Conceptual topics include the application of the quantitative analysis presented in the first FRRPP monograph for the occurrence of the FRRPP process to the polysterene-styrene-ether (PS-S-Ether) and poly(methacrylic acid)-methacrylic acid-water (PMAA-MAA-Water) systems, as well as extensions through unsteady state analysis of the occurrence of flat temperature profiles. Also, the generalization of the quantitative analysis is done to consider molecular weight effects, especially based on changes of the phase envelope to an hourglass type. Topics in implementation of the FRRPP process from pre-emulsions of monomers and the solvent/precipitant are highlighted. Additional FRRPP topics are included in this monograph that pertain to more recent efforts of Gerard Caneba, such as oil spill control, oil dispersant system, and caustic sludge remediation from emulsion-based FRRPP materials, hydrolysis of vinyl acetate-acrylic acid-based copolymers, and other polymer modification studies from FRRPP-based emulsions.
Fundamentals Of Controlled Living Radical Polymerization
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Author : Nicolay V. Tsarevsky
language : en
Publisher: Royal Society of Chemistry
Release Date : 2013
Fundamentals Of Controlled Living Radical Polymerization written by Nicolay V. Tsarevsky and has been published by Royal Society of Chemistry this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with Science categories.
Provides an in-depth history, description, and mechanistic understanding of each of the controlled/living radical polymerization techniques and practical details necessary to carry out the reactions.
Living And Controlled Polymerization
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Author : Joseph Jagur-Grodzinski
language : en
Publisher: Nova Publishers
Release Date : 2006
Living And Controlled Polymerization written by Joseph Jagur-Grodzinski and has been published by Nova Publishers this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Science categories.
The living/controlled polymerisation techniques opened new vistas in polymer chemistry. The leading authorities in this field and its pioneers contributed chapters to this collective volume. The controlled polymerisation techniques have enabled preparation of polymers, copolymers, and block copolymers with predetermined molecular weights and narrow polydispersity, in which functional groups or biologically active molecules could be placed at well defined locations. They have also enabled preparation of advanced polymeric structures with precisely determined architectures and improved properties. Moreover, they have provided opportunities for preparation of novel polymeric materials from monomers, which before have not been suitable or accessible for such purposes. Properties of some of these polymeric materials may be significantly different from those of the existing ones. They provide opportunities for new applications. Several patents have already been approved for such speciality applications as, drug delivery, biocompatible surfaces, thermoplastic elastomers, moisture curable sealants, and so on. Many more products, based on polymers fabricated by the living/ controlled polymerisation techniques, will certainly emerge in such specialised areas as, nanotechnology, medical devices, "smart polymers", sensors , smart separation technologies, optical fibres and other optical applications, various biomaterials, etc.
Controlled Living Radical Polymerization
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Author : Krzysztof Matyjaszewski
language : en
Publisher:
Release Date : 2009
Controlled Living Radical Polymerization written by Krzysztof Matyjaszewski and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Language Arts & Disciplines categories.
Recent progress in the field of controlled/living radical polymerization.
Living Radical Polymerization In Aqueous Dispersed Systems With Water Soluble Catalysts
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Author :
language : en
Publisher:
Release Date : 2015
Living Radical Polymerization In Aqueous Dispersed Systems With Water Soluble Catalysts written by 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.
Living radical polymerization is an important technique for synthesizing advanced macromolecules including block copolymers. Since its discovery in the early 1990s the capability of the field has expanded with new types of chemistry and techniques. One of the most widely used chemistries is atom transfer radical polymerization (ATRP) also known as "metal mediated living radical polymerization" (Mt-LRP). Mt-LRP has also expanded its use to aqueous dispersed systems including emulsion, miniemulsion and microemulsion, with the biggest advancements seen in miniemulsion where the droplets act as nanosized reactors. Extremely hydrophobic catalyst complexes are typically used in miniemulsion. While effective in controlling the polymerization, these hydrophobic catalyst complexes also get trapped in the final polymer particles and are difficult to remove. Herein I report the progress made using thermoresponsive polymer bound catalysts for Mt-LRP reactions in miniemulsion, which allow the successful LRP in miniemulsion with facile catalyst removal. Polymers could be prepared with less than 10 ppm of ruthenium in the final polymer compared to >500 ppm in the reaction mixture. The polymerizations were improved by the addition of ferrocene (FeCp2) in miniemulsion, to give almost complete conversion in significantly shorter times. The addition of ferrocene adds a second catalytic cycle that is ionic in nature and requires excess halogens present for a successful polymerization to occur. The ionic species in this catalytic cycle meant that the use of cationic surfactants with halogen counter-ions could directly affect the polymerization chemistry, which was shown by increasing rates with the addition of a bromine counter-ion versus a chlorine counter ion in the cationic surfactant used. Water-soluble FeCp2 derivative cocatalysts were also used to improve the rates and conversions of Mt-LRP of ruthenium catalyzed polymerizations while also allowing colourless polymers to be synthesized. Finally, the ligand EHA6TREN, was found to be active in bulk or solution (anisole) when complexed to iron (III) bromide with reverse ATRP, or to iron (II) bromide with AGET ATRP, yielding an iron-mediated living radical polymerization.
Dispersed Systems
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Author :
language : en
Publisher: Steinkopff
Release Date : 2014-03-12
Dispersed Systems written by and has been published by Steinkopff this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-03-12 with Science categories.
Polymer Science A Comprehensive Reference
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Author :
language : en
Publisher: Newnes
Release Date : 2012-12-05
Polymer Science A Comprehensive Reference written by and has been published by Newnes this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-05 with Technology & Engineering categories.
The progress in polymer science is revealed in the chapters of Polymer Science: A Comprehensive Reference, Ten Volume Set. In Volume 1, this is reflected in the improved understanding of the properties of polymers in solution, in bulk and in confined situations such as in thin films. Volume 2 addresses new characterization techniques, such as high resolution optical microscopy, scanning probe microscopy and other procedures for surface and interface characterization. Volume 3 presents the great progress achieved in precise synthetic polymerization techniques for vinyl monomers to control macromolecular architecture: the development of metallocene and post-metallocene catalysis for olefin polymerization, new ionic polymerization procedures, and atom transfer radical polymerization, nitroxide mediated polymerization, and reversible addition-fragmentation chain transfer systems as the most often used controlled/living radical polymerization methods. Volume 4 is devoted to kinetics, mechanisms and applications of ring opening polymerization of heterocyclic monomers and cycloolefins (ROMP), as well as to various less common polymerization techniques. Polycondensation and non-chain polymerizations, including dendrimer synthesis and various "click" procedures, are covered in Volume 5. Volume 6 focuses on several aspects of controlled macromolecular architectures and soft nano-objects including hybrids and bioconjugates. Many of the achievements would have not been possible without new characterization techniques like AFM that allowed direct imaging of single molecules and nano-objects with a precision available only recently. An entirely new aspect in polymer science is based on the combination of bottom-up methods such as polymer synthesis and molecularly programmed self-assembly with top-down structuring such as lithography and surface templating, as presented in Volume 7. It encompasses polymer and nanoparticle assembly in bulk and under confined conditions or influenced by an external field, including thin films, inorganic-organic hybrids, or nanofibers. Volume 8 expands these concepts focusing on applications in advanced technologies, e.g. in electronic industry and centers on combination with top down approach and functional properties like conductivity. Another type of functionality that is of rapidly increasing importance in polymer science is introduced in volume 9. It deals with various aspects of polymers in biology and medicine, including the response of living cells and tissue to the contact with biofunctional particles and surfaces. The last volume is devoted to the scope and potential provided by environmentally benign and green polymers, as well as energy-related polymers. They discuss new technologies needed for a sustainable economy in our world of limited resources. Provides broad and in-depth coverage of all aspects of polymer science from synthesis/polymerization, properties, and characterization methods and techniques to nanostructures, sustainability and energy, and biomedical uses of polymers Provides a definitive source for those entering or researching in this area by integrating the multidisciplinary aspects of the science into one unique, up-to-date reference work Electronic version has complete cross-referencing and multi-media components Volume editors are world experts in their field (including a Nobel Prize winner)
Living Controlled Radical Polymerization
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Author : Delphine Chan-Seng
language : en
Publisher:
Release Date : 2007
Living Controlled Radical Polymerization written by Delphine Chan-Seng and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
Emulsion polymerization is an important process for the industrial production of polymers. However, initial attempts at performing "living"/controlled radical polymerization under emulsion conditions were not particularly successful primarily due to latex instability. To address this problem a unique nanoprecipitation process was developed in our laboratory for the stable free radical polymerization (SFRP) process. The first part of this thesis describes attempts to generalize this process and extend it to the copper based atom transfer radical polymerization, ATRP, process. Details describing initial problems we had with reproducing some initial successful results are provided. Once the process was under control it was used to synthesize block copolymers. The ability of these block copolymers to self-assemble in aqueous solutions and in bulk were subsequently investigated and the results of these studies are detailed at the end of the discussion on the emulsion process. The second part of the thesis deals with the SFRP process and more specifically with the difficulty of the process to moderate the polymerization of acrylates. Two reasons have been advanced to account for this difficulty; a high bond dissociation energy between the C-O bond linking the nitroxide moiety to the end of the polymer chain and an accumulation of excess nitroxide, caused by unavoidable chain termination, which causes inhibition of the polymerization. To address the high bond dissociation energy a nitroxide, specifically, 1,1'-diadamantyl nitroxide, containing very bulky substituents that might cause the bond to weaken, was synthesized and studied. To address the accumulation of excess free nitroxide, high temperature additives, that would slowly dissociate over time and consume the excess nitroxides, were studied. The results of both of these approaches are provided enabling some insight into what might be actually restricting the polymerization of acrylates.