Download or read book Investigation of Kinetics of Nitroxide Mediated Radical Polymerization of Styrene with a Unimolecular Initiator written by Mingxiao Zhou and published by . This book was released on 2009 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents the results of a study on the kinetics of nitroxide-mediated radical polymerization of styrene with a unimolecular initiator. The primary objective was to obtain a more comprehensive understanding of how a unimolecular-initiating system controls the polymerization process and to clarify the effects of various reaction parameters. Previous work in this field has met with some difficulties in the initiator synthesis, such as low yield and inconsistency of molecular weight. These problems were overcome by adjusting reaction conditions and procedures. Better yields of initiator with consistent molecular weight were produced by the improved methods. Control of polymerization rate and polymer molecular weight in unimolecular nitroxide-mediated radical polymerization was studied by looking at the effects of the three main factors: initiator concentration, temperature, and the initiator molecular weight on polymerization rate, molecular weight and polydispersity. Results indicated that increasing the initiator concentration had no effect on polymerization rate at low conversion, but led to lower polymerization rate at high conversion; higher initiator concentration led to lower molecular weight of the resulting polymer. It was also found that temperature significantly increased the polymerization rate, yet had no effect on number-average molecular weight, Mn, at low conversion, while it caused a plateau at high conversion levels; there was no effect on weight-average molecular weight, Mw, through the whole conversion range. In addition, increasing initiator molecular weight was found to have no effect on either polymerization rate or molecular weight. The experimental molecular weights of the unimolecular system were compared to theoretical molecular weights based on ideal controlled radical polymerization (CRP). The results were found to be close to the theoretical values. This confirmed the advantages of the unimolecular system, namely, the degree of control over molecular weight was nearly ideal (for certain conditions); and molecular weights could thus be predicted by simply following general rules relating to CRP mechanisms.

Download or read book INVESTIGATIONS OF KINETIC ASPECTS IN NITROXIDE MEDIATED RADICAL POLYMERIZATION OF STYRENE written by Afsaneh Nabifar and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Exploiting Nitroxide mediated Controlled Radical Polymerization written by Maisha Kito Gray and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: By employing the appropriate choice and concentration of unimolecular initiator (A-T) or polystyrene (PS) macroinitiator, one allowing polymerization to proceed at moderate reaction temperatures (80--100°C), PS homopolymers with MWs in excess of 100,000 g/mol, possibly approaching 238,000 g/mol, have been made in a controlled manner (i.e., with polydispersity remaining below 1.5 and average chain length growing with increasing conversion).

Download or read book Radical Polymerization written by Michael Buback and published by John Wiley & Sons. This book was released on 2007-07-16 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: The IUPAC-sponsored International Symposium on "Radical Polymerization: Kinetics and Mechanism" was held in Il Ciocco (Italia) during the week September 3-8, 2006. It was the fourth within the series of so-called SML conferences, which are the major scientific forum for addressing kinetic and mechanistic aspects of free-radical polymerization and of ontrolled radical polymerization. Top international authors like K. Matyjaszewski, T. P. Davis, T. Fukuda and others present their latest research. The five major themes covered were: Fundamentals of Free-Radical Polymerization, Heterogeneous Polymerization, Controlled Radical Polymerization, Polymer Reaction Engineering, and Polymer Characterization. SML IV again marked an important step forward toward the better understanding of the kinetics and mechanism of radical polymerization, which is extremely relevant for both conventional and controlled radical polymerization and for people in academia as well as in industry.

Download or read book The Design Synthesis and Testing of N alkoxy Amine Initiators for Nitroxide mediated living Free Radical Polymerization written by Aaron Nilsen and published by . This book was released on 2005 with total page 1088 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Radical Polymerization Kinetics and Mechanism written by and published by Cuvillier Verlag. This book was released on 2006-08-22 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation of Nitroxide mediated Thermal and Photochemical Reactions of Living Free Radical Polymerization written by William G. Skene and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work presented in this thesis deals primarily with living free radical polymerization (LFRP). Two main specific areas of this process have been studied; thermal and photochemical reaction sequences. Stoichiometric unimolecular initiators were found to be ideal probes for studying the reactions involved in the LFRP process. The bond dissociation energy (BDE) of the labile C-O bond of the alkoxyamine initiators was found to be ca. 28 kcal/mol and is dependent on the resulting carbon centered radical produced upon thermal decomposition. Lower activation energies were measured for more stable carbon centered radicals. Complementary to the thermal studies, photoacoustic studies (PAC) involving photochemical decomposition of the initiators led to the homolytic N-O and C-O bond cleavages in addition to disproportionation product formation. The BDE for the N-O bond of these initiators is ca. 43 kcal/mol. These studies also provided insight into volume effects, where a strict homologous solvent series is not required for extrapolating true enthalpies of reactions and volume correction factors for PAC. The decomposition quantum yields of a series of ketone based actinometers used for PAC BDE studies were re-evaluated and found to be solvent independent. The specific kinetics of thermal LFRP were equally investigated through the use of probes which are normally used for thermal initiation. Fast time resolved techniques of laser flash photolysis (LFP) were used to measure the bi-molecular rate constant for the coupling reaction between a carbon centered radical and a nitroxide radical involved in LFRP. Typical values lay in the area of 108 M-1 s-1 and are influenced by the structure of the carbon centered radical and not that of the nitroxide. The rate constants were observed to be slower with more stable carbon centered radicals, similar to the BDE results where weaker dissociation energies were observed. The formation of minor disproportionation products upon thermal decomposition of the unimolecular initiators was assigned to a concerted four center elimination ultimately responsible for the lack of controlled polymerization with acrylates. The incorporation of steric effects into the monomer or the nitroxide suppressed the formation of these products by increasing the energy barrier necessary for correct orbital alignment required for the elimination reaction. Living polymerization of acrylate monomers was achieved with a nitroxide containing bulky substituents in its 2 and 6 positions. Moderate success of living polymerization was also achieved with acrylate type monomers through the use of an additional phase not miscible with the bulk phase. Chromophores producing triplet states upon excitation were found to undergo fast and efficient energy transfer to a covalently linked alkoxyamine subsequently promoting C-O bond homolysis. The orientation of the C-O bond relative to the chromophore in addition to the distance separating the two influences the efficiency of energy transfer and bond cleavage. Using a benzophenone type chromophore with a covalently linked alkoxyamine initiator promoted photoinduced living type polymerization of acrylate.

Download or read book The Kinetics of Free Radical Polymerization written by Alastair M. North and published by Pergamon. This book was released on 1966 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Kinetic Investigation of the Atom Transfer Radical Polymerization of Styrene in Homogeneous Systems written by and published by . This book was released on 1996 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Controlled/'Living' radical polymerization allows for the preparation of complex polymer architectures, end functional polymers and block copolymers. Recently, we reported atom transfer radical polymerization (ATRP), a novel route to the controlled - 'Living' - radical polymerization in which polymers with predetermined molecular weight up to Mn =100,000 and polydispersity as narrow as 1.05 have been obtained. In this paper, the kinetic scheme of atom transfer radical polymerization of styrene under homogeneous conditions is described. The polymerization was determined to be first order with respect to the concentration of monomer, initiator and Cu(I) halide. From the effect of the ratio of ligand to Cu(I) halide, possible active copper complex was proposed.

Download or read book Controlled Radical Polymerization written by and published by . This book was released on 2015 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reversible deactivation radical polymerization (RDRP), also known as controlled radical polymerization (CRP), has been a significant area of polymer research for more than 20 years, allowing the facile synthesis of complex macromolecules previously unattainable by conventional free radical polymerization (FRP). However, industrial adoption of RDRP has been minimal largely due to the significant economic barrier to commercialization, with complex synthesis of the mediating agents required and the necessary post polymerization processing to recover the mediating agent. In an effort to overcome this obstacle to industrial adoption, the mediating agent concentration can be significantly reduced, such as the copper level in activator regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP), or the mediating agent can be incorporated into the polymer as in nitroxide-mediated polymerization (NMP), where no post polymerization processing is required other than removal of residual monomer. This thesis presents a study of these two chemistries towards industrially relevant conditions. To build upon recent developments of continuous ARGET ATRP, a systematic batch study is conducted to pursue decreased copper levels in the generation of short chain acrylic and methacrylic polymers of interest to the coatings industry. The limitations to reducing copper levels are understood with the development of a kinetic model, with the improved understanding of the ARGET ATRP system suggesting that a reduction in copper loading must be accompanied by an increase in reducing agent loading in order to maintain an appreciable polymerization rate. Alternatively, NMP does not require a reduction in mediating nitroxide level as it reversibly terminates the polymer chain end, and may present a smaller barrier to commercialization. Indeed, certain nitroxides are currently produced at pilot scale. However, limited research has been conducted into continuous operation which is commonly used in industry to improve productivity. A batch NMP study at elevated temperatures demonstrates the effectiveness of a novel alkoxyamine to mediate the polymerization of styrene and butyl acrylate under industrially relevant conditions. A kinetic study is developed to understand the novel system, and the polymerization is implemented in a continuous stirred-tank reactor (CSTR), the first demonstration of NMP in an existing industrial process.

Download or read book New Initiators and Catalysts for Radical Living Radical and Ring Opening Polymerizations written by Yanhui Chen and published by . This book was released on 2008 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Emulsion Polymerization and Emulsion Polymers written by Peter A. Lovell and published by John Wiley & Sons. This book was released on 1997-04-03 with total page 858 pages. Available in PDF, EPUB and Kindle. Book excerpt: Emulsion Polymerization and Emulsion Polymers Edited by Peter A. Lovell Manchester Materials Science Centre, UMIST, Manchester, UK and Mohamed S. El-Aasser Emulsion Polymers Institute and Department of Chemical Engineering, Lehigh University, Bethlehem, PA, USA Emulsion polymerization is a technologically and commercially important reaction used to produce synthetic polymers and latexes for a wide range of applications. It is the basis of a massive global industry that is expanding due to the versatility of the reaction and the greater realization of the ability to control properties of the polymer latexes produced. Emulsion Polymerization and Emulsion Polymers provides an up-to-date treatment of both academic and industrial aspects of the subject in a single self-contained volume. Established knowledge is integrated with latest developments and introductory chapters to give a state-of-the-art summary which is also suitable as a broad based introduction to the field. The individual chapters have been written by specialists from academia and industry and are presented in a way which ensures that the book will be of equal value to experienced researchers and students.

Download or read book Experimental and Modelling Investigation of a Novel Tetrafunctional Initiator in Free Radical Polymerization electronic Resource written by Matthew Scorah and published by University of Waterloo. This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nitroxide Mediated Synthesis of Protected Styrenesulfonate and Acrylonitrile Copolymers for Membrane and Barrier Materials written by Valerie A. L. Consolante and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Controlled free radical polymerization is attractive as it produces polymers with well defined microstructures typically associated with "living" polymerization methods, using a wide range of monomers required for applications such as nanoporous membranes and barrier materials. Poly(trioctylammonium p-styrenesulfonate) homopolymer (poly(SS-TOA)) and poly(SS-TOA-ran-styrene) copolymers were synthesized by nitroxide-mediated polymerization (NMP) using an N-tert-butyl-N-[1-diethylphosphono-(2,2-dimethylpropyl)] nitroxide (SG1) based unimolecular initiator, called BlocBuilder. Polymerizations were controlled for low theoretical molecular weight at complete conversion (Mn, theoretical = 20 kg·mol-1), resulting in very low polydispersities (Mw/Mn

Download or read book Radical Polymerization Kinetics and Mechanism written by Michael Buback and published by . This book was released on 2006 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: