Dissertationen zum Thema „Polymerization“
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1
Hajime, Kammiyada. „Ring-Expansion Cationic Polymerization：A New Precision Polymerization for Cyclic Polymers“. 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225628.
2
Aran, Bengi. „Polymerization And Characterization Of Methylmethacrylate By Atom Transfer Radical Polymerization“. Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605042/index.pdf.
Annotation:
In this work, methylmethacrylate, MMA was polymerized by ATRP method to obtain low molecular weight living polymers. The initiator was p-toluenesulfonylchloride and catalyst ligand complex system were CuCl-4,4&rsquodimethyl 2,2&rsquo
bipyridine. Polymers with controlled molecular weight were obtained. The polymer chains were shown by NMR investigation to be mostly syndiotactic. The molecular weight and molecular weight distribution of some polymer samples were measured by GPC method. The K and a constants in [h]=K Ma equation were measured as 9.13x10-5 and 0.74, respectively. FT-IR and X-Ray results showed regularity in polymer chains. The molecular weight-Tg relations were verified from results of molecular weight-DSC results.
3
Barnette, Darrell Thomas. „Continuous miniemulsion polymerization“. Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/12518.
4
Endsor, Robert M. „Living cationic polymerization“. Thesis, Aston University, 1997. http://publications.aston.ac.uk/9597/.
Annotation:
The kinetics of the polymerization of styrene iniated by 1-chloro-1-phenyltehane/tin (IV) chloride in the presence of tetrabutylammonium chloride have been studied. Dilatometry studies at 25 °C were conducted and the orders of reaction were established. Molecular weight studies were conducted for these experiments using size exclusion chromatography. These studies indicated that transfer/termination reactions were present. The observed kinetics may be explained by a polymerization mechanism involving a single propagating species which is present in low concentrations. Reactions at 0 °C and -15 °C have shown that a "living" polymerization could be obtained at low temperatures. A method was derived to study the kinetics of a "living" polymerization by following the increase in degree of polymerization with time. Polymerizations of styrene were conducted using 1,4-bis(bromomethyl)benzene as a difunctional co-catalyst. These reactions produced polymers with broad or bimodal molecular weight distributions. These observations may be explained by the rate of initiation being slower than the rate of propagation or the presence of transfer/termination reactions. Reactions were conducted using a co-catalyst using a co-catalyst produced by the addition of 1,1-diphenylethane to 1,4-bis(bromomethyl)benzene. Size exclusion chromatography studies showed that the polymers produced had a narrower molecular weight distribution than those produced by polymerizations initiated by 1,4-bis(bromomethyl)benzene alone. However the polydispersity was still observed to increase with reaction time. This may also be explained by slow initiation compared to the rate of propagation. Polymerizations initiated by both bifunctional initiators were examined using the method of studying reaction kinetics by following the change in number average degree of polymerization. The results indicated that a straight line relationship could also be obtained with a non-living polymerization.
5
Brodsky, Colin John. „Graft polymerization lithography“. Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3024998.
6
Vale, Hugo. „Population Balance Modeling of Emulsion Polymerization Reactors : applications to Vinyl Chloride Polymerization“. Lyon 1, 2007. http://www.theses.fr/2007LYO10034.
Annotation:
This thesis is a contribution to the development of population balance models of emulsion polymerization and, more particularly, to the modeling of particle formation and particle size distribution (PSD) in vinyl chloride emulsion polymerization. The rst part of the work is dedicated to the acquisition of experimental data. Ab initio polymerizations were done to obtain reliable data regarding the dependence of the particle number on the concentration of surfactant, as well as to analyze the effect of the initiator concentration, stirring rate, and monomer-to-water ratio upon the particle number and the polymerization kinetics. In addition, seeded polymerizations were carried out at different concentrations of seed latex and emulsifier in order to quantify the influence of these factors on the onset and extent of secondary particle formation. Moreover, the adsorption isotherms of SDS and SDBS on poly (vinyl chloride) latex particles were determined. The second part of the manuscript focuses on the development of the population balance model. A special feature of the model proposed in this work is the computation of the coupled radical number and particle size distributions by the zero-one-two population balance equations. Overall, the examples presented show that the model can capture the tendencies observed in the polymerizations with physically reasonable values of the unknown/ adjustable parameters. With respect to particle formation, it was seen that including the possibility of particle nucleation (homogeneous and micellar) by exited radicals helps to explain the high particle numbers observed and the fact that the initiator concentration has a negligible effect on the particle number. Moreover, it was demonstrated that particle coagulation must be taken into account in order to obtain plausible PSDs and to avoid the use of abnormally low values of the efficiency of radical entry into micelles. In the third and last part, two novel numerical methods for the solution of population balances of interest to emulsion polymerization systems are presented and discussedCette thèse est une contribution au développement de modèles mécanistiques de la polymérisation en émulsion et, plus particulièrement, une contribution à la modélisation de la formation des particules et de leur distribution de taille (DTP) lors de la polymérisation en émulsion du chlorure de vinyle. La première partie de l'étude est consacrée à l'obtention de données expérimentales. Des polymérisations ab initio ont été réalisées afin d'obtenir des données fiables sur l'effet de la concentration de tensioactif, concentration d'initiateur, vitesse d'agitation et rapport monomère/eau sur le nombre de particules formées et sur la cinétique de polymérisation. Des polymérisations ensemencées ont également été réalisées afin de déterminer l'influence de la quantité de semence et de la concentration de tensioactif sur la formation de particules par nucléation secondaire. Enfin, les isothermes d'adsorption du SDS et du SDBS sur des particules de latex de poly (chlorure de vinyle) ont été déterminées. La deuxième partie de l'étude concerne le développement et la validation du modèle de polymérisation. Celui-ci à la particularité d'utiliser les bilans de population propres aux systèmes ‘zéro-un-deux' pour déterminer la distribution jointe du nombre de radicaux et de la taille des particules. Dans l'ensemble, les résultats obtenus montrent que le modèle proposé est capable de décrire les principaux comportements retrouvés lors des polymérisations avec des valeurs physiquement plausibles des paramètres inconnus ou ajustables. Pour ce qui concerne la formation des particules, il s'avère que la prise en compte de la possibilité de nucléation (homogène ou micellaire) par les radicaux désorbés aide à expliquer les valeurs élevées du nombre de particules ainsi que l'effet négligeable de la concentration d'initiateur sur le nombre de particules. En autre, il est démontré que le phénomène d'agrégation des particules doit être pris en considération afin d'obtenir des DTPs cohérentes. Dans la troisième et dernière partie, deux nouvelles méthodes numériques pour la résolution de bilans de population d'intérêt pour la modélisation des systèmes de polymérisation en émulsion sont proposées et analysées
7
Ding, Shijie. „Atom transfer radical polymerization“. Laramie, Wyo. : University of Wyoming, 2006. http://proquest.umi.com/pqdweb?did=1225138911&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
8
Song, Zhiqiang. „Kinetics of emulsion polymerization“. Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/10148.
9
Wong, Ji Sam. „Modeling polymerization-based amplification“. Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104123.
Annotation:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2016.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 117-120).
Eosin, a photoreducible xanthene derivative, acts as a Type II photoinitiator of free radical polymerizations when used in combination with alcohols or amines as co-initiators. Previous work utilizing eosin in polymerizations focused on high concentrations of initiators but it has recently been gaining use in bio-applications at lower concentrations due to its ability to initiate polymerizations when illuminated by harmless visible light even in the presence of orders-of-magnitude larger amounts of dissolved oxygen which acts as an inhibitor. We investigated the mechanism behind eosin's role in the polymerization process and its ability to initiate polymerization at concentrations lower than that of oxygen. A series of model simulation studies that systematically examined the effects of including additional elementary reactions based on proposed reactions in published literature into the classical free radical polymerization scheme without fitting any unknown parameters to experimental results were performed and analyzed. The first study examined the effect on having an eosin regeneration reaction between the reduced eosin radical which is formed during the photogeneration of free radicals, and the peroxy radical formed by inhibiting reactions of propagating radicals with oxygen. This reaction results in an unreactive hydroperoxy species and the regeneration of ground state eosin which can then produce even more radicals that undergo propagation. The simulation results indicated that the additional eosin regeneration reaction did explain eosin's ability to initiate polymerization at lower concentrations than oxygen, but the best predicted times required for the formation of polymer was larger than experiments by an order of magnitude, suggesting that the reaction scheme was incomplete. We subsequently incorporated an amine chain peroxidation reaction into the overall reaction scheme and determined the effects of such a change. The amine chain peroxidation reaction involves the peroxy radical extracting a hydrogen atom from the tertiary amines present in the reaction mixture, forming an unreactive hydroperoxide species and an amino-radical that can further undergo propagation. The addition of this reaction greatly increased the rate of oxygen consumption and reduced the predicted polymerization times to an order of magnitude lower than experiments. In addition to purely kinetic studies on the overall reaction scheme, a one-dimensional reaction-diffusion model was also created to understand the effects of having a continuously diffusing oxygen flux on the overall polymerization process. The time course of polymerization and spatial variations when using the various reaction schemes were analyzed and contrasted. The models predicted the formation of a reaction front which forms at the onset of polymerization and slowly moves towards the closed surface, tracking the diffusion of oxygen back into the reaction system. A surface region of higher eosin concentrations was also simulated to model the effects of binding events occurring in polymerization-based amplification (PBA). The addition of a small amount of eosin on the surface resulted in slightly faster predicted polymerization times close to the surface, similar to experimental observations where a surface polymer is first formed before the whole solution polymerizes where binding events have occurred.
by Ji Sam Wong.
Ph. D.
10
Qi, Genggeng. „Unconventional radical miniemulsion polymerization“. Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26547.
Annotation:
Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2009.Committee Chair: Jones, Christopher W.; Committee Chair: Schork, F. Joseph; Committee Member: Koros, William J.; Committee Member: Lyon, Andrew; Committee Member: Nenes, Athanasios. Part of the SMARTech Electronic Thesis and Dissertation Collection.
11
Lin, Anna. „Nitroxide-mediated photo-polymerization“. Electronic Thesis or Diss., Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0264.
Annotation:
De nos jours, la photopolymérisation est devenue un procédé important dans le domaine de la science des polymères. Cette méthode présente de nombreux avantages : la rapidité de la réaction, l‘aspect environnemental (formation limitée de composés organiques volatils et possibilité de réaction à température ambiante) ou encore un contrôle spatial et temporel. Ce mode d‘activation photochimique appliqué pendant les dernières décennies aux techniques de polymérisation radicalaire contrôlée telles que l‘ATRP, la RAFT ou la NMP permet de contrôler les propriétés des polymères mais aussi la préparation de polymères à blocs. Parmi ces techniques, la photopolymérisation contrôlée par les nitroxydes (NMP²) nécessite l‘utilisation d‘une alcoxyamine photosensible dont un groupement chromophore est porté par un nitroxyde. Dans ce manuscrit, nous présentons aussi bien la préparation d‘alcoxyamines photosensibles que les études de leurs propriétés photochimiques analysées par spectroscopie d‘absorption et par expériences de résonance paramagnétique électronique. Nous avons évalué les capacités de polymérisation des meilleurs candidats obtenus dans des conditions de NMP². Enfin, une autre méthode a été testée en effectuant une réaction de NMP² à partir d‘alcoxyamines produites par ESCP (Enhanced Spin Capturing Polymerization) ou par NMRC (Nitrone-Mediated Radical Coupling)Nowadays, photopolymerization has become an important process in the field of polymer science. This method presents several advantages such as the speed of the reaction, the environmental-friendly side (limited formation of released volatile organic compound and possibility of a reaction at room temperature) but also a spatial and temporal control. This photochemical approach applied in the past decades to controlled radical polymerization techniques such as ATRP, RAFT or NMP enable the control of polymer properties but also the preparation of block polymers. Among these techniques, the Nitroxide-Mediated Photopolymerization (NMP²) requires the use of a photosensitive alkoxyamine which has a chromophore group on the nitroxide moiety. In this manuscript, we present both the synthesis of photosensitive alkoxyamines and the studies of their photochemical properties investigated by absorption spectroscopy and by electron spin resonance experiments. We evaluated the polymerization abilities of the best obtained candidates. Finally, another approach has been tested to perform a reaction of NMP² from alkoxyamines made by ESCP (Enhanced Spin Capturing Polymerization) or via NMRC (Nitrone-Mediated Radical Coupling)
12
Reeves, Jennifer Anne. „Photochemistry: Its Application to Reversible Deactivation Radical Polymerization, Degradation, and Post-polymerization Modification“. Miami University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=miami154297403540796.
13
Aoshima, Sadahito. „Syntheses of Functional Polymers by Cationic Polymerization: Living Polymerization and Controlled Chain Transfer“. Kyoto University, 1986. http://hdl.handle.net/2433/74688.
14
Salehpour, Somaieh. „Biodiesel: A green polymerization solvent“. Thesis, University of Ottawa (Canada), 2007. http://hdl.handle.net/10393/27916.
Annotation:
A number of polymer products are traditionally made using a solution polymerization technique. However, with increased environmental awareness and thus, concerns over the volatile organic content (VOC) associated with various polymer processes, there is an ongoing effort to find alternatives to traditional solvents.
In an effort to use cleaner technologies, fatty acid methyl ester (FAME) was used for the first time as a polymerization solvent. Biodiesel or FAME has garnered much attention in recent years as an alternative to diesel fuel. It is environmentally benign and has a low volatility. Because biodiesel is a high boiling solvent, its use can increase productivity by enabling polymerizations at elevated temperatures. This would result in faster reaction rates and thus, shorter reaction times.
In the first part of this study, solution polymerizations of four commercially important monomers (i.e., methyl methacrylate (MMA), styrene, butyl acrylate (BA) and vinyl acetate (VAc)) were studied at 60°C using FAME produced from canola oil as a solvent. Reactions were carried out at different solvent concentrations to verify the effect of the FAME on the polymerizations. Chain transfer to solvent rate parameters were obtained using the Mayo method. In addition, the effect of solvent on solution polymerizations of each monomer was investigated. This was suspected to contribute to a change in the lumped kinetic parameter (kp/kt1/2). The collected kinetic experimental data were modeled using a polymerization simulator.
In the second part of this thesis, canola-based FAME was used as a high boiling solvent in the solution polymerization of the aforementioned monomers at 120°C. Chain transfer to solvent rate constants were calculated and were employed in a polymerization simulator to predict the polymerization rates and the cumulative average molecular weights of the polymer product. As in the study at 60°C, changes in the lumped kinetic parameter with solvent concentration were incorporated into the free radical polymerization simulator; these changes considerably improved the model predictions.
In the third part of the thesis, the effect of FAME produced from different oil feedstocks on polymerization kinetics was investigated for styrene homopolymerizations at 60°C. Soybean oil, and 50% yellow grease-50% canola oil were the feedstocks employed in this study. Experimental results were compared to the runs using canola-based FAME at 60°C. Chain transfer to solvent constants were estimated for each solvent using the Mayo method and no significant difference between the values obtained from polymerization in different FAME was found. On the other hand, dissimilar effects on the rate of polymerization were observed. These were shown to relate to the degree of unsaturation of each FAME type. Model predictions of reaction rates and molecular weights for the investigated systems are also presented.
15
Reinhardt, Jeff C. „Precipitation/dispersion polymerization of acrylamide“. Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/10210.
16
Vogt, Marc. „Polymerization dynamics in nonequilibrium environments“. Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/27698.
17
Howard, Bruce. „Polymerization of 2D gravity models“. Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301443.
18
Ishihara, Nobuhide. „Transition metal catalyzed olefin polymerization“. Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253375.
19
Walker, Dennis Allan. „New approaches to polymerization catalysis“. Thesis, University of East Anglia, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251449.
20
Ryan, Martin Edward. „Mechanistic studies of plasma polymerization“. Thesis, Durham University, 1995. http://etheses.dur.ac.uk/5455/.
Annotation:
Plasma polymerization is a solventless method for depositing polymeric layers onto any substrate at room temperature. This technique comprises excitation, fragmentation, and polymerization of precursor molecules by an electrical discharge. Although widely used, the fundamental molecular processes associated with plasma polymerization are not fully understood. Basic plasma / polymer interactions were studied by investigating the surface treatment of polytetrafluoroethylene (PTFE) using inert and reactive gas discharges. Depending upon the feed gas employed, chemical, UV, or ion beam modification of the PTFE surface were found to be important. Argon glow discharge treatment was found to result in similar physicochemical phenomena at the PTFE surface to that observed during argon ion beam studies, thereby supporting the relative importance of ion bombardment during noble gas plasma modification. In high power discharges it has been shown that extensive ion bombardment of PTFE can lead to the simultaneous sputtering and plasma polymerization of ejected species onto an adjacent substrate. The chemical nature of the resultant fluorocarbon deposits for various gases was found to correlate to the earlier surface treatment studies. Another way of carrying out plasma polymerization is to use pulsed plasmas; these offer the advantage of greater retention of monomer structure within the plasma polymer matrix. In the case of maleic anhydride less fragmentation of the precursor, reduced beam damage of the polymer, and radically initiated polymerization was observed by increasing the off-period of the pulse. Similarly the structural characteristics of 2- iodothiophene plasma polymers were found to be influenced by the electrical discharge power and pulsing parameters leading to a gradual destruction of the aromatic ring structure.
21
Ren, Wendong. „Photoinduced Atom Transfer Radical Polymerization“. University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1619122320374689.
22
Tapper, Tristan T. „Living cationic polymerization of isobutene“. Thesis, Aston University, 1999. http://publications.aston.ac.uk/9621/.
Annotation:
The polymerization of isobutene initiated by 1-chloro-1-phenylethane has been investigated, and molecular weight studies conducted using size exclusion chromatography. Polymerizations carried out in a 40/60 (v/v) mixture of dichloromethaneIcyclohexane, using titanium (IV) chloride as a catalyst in the presence of pyridine at -30 °C were found to be controlled and living. The number average molecular weights of the polymers increased linearly with monomer conversion, and the molecular weight distributions were between 1.15 and 1.20. Efficiencies of initiation were between 80 and 100%, and evidence was found to suggest that backbiting to the initiator had occurred, resulting in the formation of cyclic oligomers during the early stages of polymerization. The kinetics of polymerization can be explained in terms of active species in. equilibrium with dormant species. The effects of temperature. and dielectric constant on this equilibrium were studied and a model based upon the Fuoss equation was developed. Pyridine was found to behave as proton trap in the system, and when it was used in excess the rate of polymerization was retarded. By assuming that the catalyst and pyridine formed a one to one complex, it was possible to show that the reaction was second order with respect to the catalyst. The synthesis of low molecular weight polyisobutenes was studied. When the concentration of initiator was increased relative to that of the isobutene, such that the theoretical degree of polymerization was 20 or less, the rate of initiation was slow compared to propagation. The efficiency of initiation in these polymerizations was typically between 30 and 40 %. Optimal conditions of temperature. and.catalyst concentration were established, leading to a 60 % efficiency of initiation. A one-pot synthesis of phenol end-capped polyisobutene was attempted by adding phenol at the end of a living polymerization. Evidence to substantiate the existence of capped polymer chains in the resultant product was inconclusive. Block copolymerizations of oxetane and isobutene were conducted using 1-chloro-1phenylethane/TiCl4, but no copolymer or oxetane homopolymer could be isolated.
23
Brunier, Barthélémy. „Modeling of Pickering Emulsion Polymerization“. Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10320/document.
Annotation:
L’objectif du présent projet est de développer une méthodologie pour la modélisation fondamentale de procédés de polymérisation en émulsion sans tensioactif stabilisés par des particules inorganiques, dénommées "polymérisation en émulsion Pickering". La modélisation des systèmes de polymérisation en émulsion nécessite la modélisation de la distribution de taille des particules (PSD), qui est une propriété importante d'utilisation finale du latex. Cette PSD comprend des sous-modèles dédiés à la nucléation des particules, le transfert de masse entre les différentes phases (monomère, radicaux, stabilisant) et la coagulation des particules. Ces modèles devraient de préférence être validés expérimentalement de manière individuelle. La première partie principale du travail est consacrée à l'étude expérimentale. Cette partie peut être divisée en trois parties. La première partie décrit l'adsorption de particules inorganiques sur le polymère sans réaction. Une adsorption multicouche a été observée et l’isotherme B.E.T. a été capable de décrire cette adsorption. L'adsorption se révèle être plus importante pour une force ionique plus élevée. La dynamique d'adsorption semple être rapide et par conséquent le partage peut être considéré à l'équilibre pendant la polymérisation. La deuxième partie concerne l'étude de différents paramètres de réaction sur le nombre de particules et la vitesse de réaction dans des polymérisations ab initio. L'effet du mélange, de la concentration initiale des monomères et de la concentration de l'initiateur a été étudié. L'optimisation de ces conditions a été utile pour la partie de modélisation. La dernière partie décrit les différences entre plusieurs Laponite® à travers la polymérisation en émulsion ab initio du styrène.La deuxième partie principale du manuscrit a porté sur la modélisation de la polymérisation en émulsion Pickering. Le modèle de bilan de population et le nombre moyen de radicaux par particule ont été calculés en fonction de l'effet des particules organiques. La croissance des particules de polymère a été optimisée en ajustant les modèles d'entrée et de désorption des radicaux décrits dans la littérature aux données expérimentales. Aucune modification n'a été nécessaire, ce qui nous a permis de conclure que l'argile n'avait aucune influence sur l'échange radical. Cependant, la stabilisation joue un rôle important dans la production de particules de polymère. Le modèle de nucléation coagulante a été capable de décrire le taux de nucléation et de prédire le nombre total de particulesThe aim of the present project is to develop a methodology for fundamental modeling of surfactant-free emulsion polymerization processes stabilized by inorganic particles, referred to as “Pickering emulsion polymerization”. Modeling emulsion polymerization systems requires modeling the particle size distribution (PSD), which is an important end-use property of the latex. This PSD includes submodels dedicated to particle nucleation, mass transfer between the different phases (monomer, radicals, stabilizer), and particle coagulation. These models should preferably be individually identified and validated experimentally. The first main part of the work is dedicated to the experimental study. This part can be divided in three parts. The first part describes the adsorption of inorganic particles on polymer without reaction. Multilayer adsorption was observed and B.E.T. isotherm was able to describe this adsorption. The adsorption was found to be enhanced at higher ionic strength. The adsorption dynamics were found fast and therefore clay partitioning can be considered at equilibrium during polymerization. The second part concerned the investigation of different reaction parameters on the particles number and reaction rate in ab initio polymerizations. The effect of mixing, initial monomer concentration and initiator concentration were considered. Optimization of these conditions was useful for the modeling part. The last part described the differences between several LaponiteR_ grades through the ab initio emulsion polymerization of styrene. The second main part of the manuscript focused on the modeling of the Pickering emulsion polymerization. The population balance model and average number of radicals balance were adapted regarding the effect of inxi organic particles. The growth of the polymer particles was optimized by fitting the models of radicals’ entry and desorption described available in literature to the experimental data. No modification was needed, which allowed us to conclude that the clay had no influence on radical exchange. However, LaponiteR_ stabilization played an important role in polymer particles production. Coagulative nucleation model was able to describe the nucleation rate and predict the total number of particles
24
Sisson, Thomas Michael 1966. „Crosslinking polymerization in supramolecular assemblies“. Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282566.
Annotation:
Supramolecular assemblies are composed of noncovalently associated molecules which organize in water to yield 2-D and 3-D architectures. Crosslinking polymerization of supramolecular assemblies provides an effective means to modify their chemical and physical properties. Two methods of characterizing crosslinked polymeric assemblies were developed. These techniques rely on experimentally observed changes in polymer solubility and assembly stability in the presence of nonionic surfactants. The results show an inefficient crosslinking mechanism in organized media compared to isotropic polymerization. Two models rationalizing the inefficient crosslinking observed in organized media were proposed. Symmetrical crosslinking agents were synthesized to test the models. These results suggest intramolecular memorialization is an important process in the efficiency of crosslinking. The polymerization of a heterobifunctional lipid with two polymerizable groups in the same acyl chain separated by a six carbon spacer yielded a novel linear ladder-like polymer architecture. The two reactive groups are in regions of different polarity allowing for the simultaneous, selective, and sequential polymerization depending on the initiation chemistry employed. A second heterobifunctional lipid was designed and synthesized with a longer spacer between the two reactive groups. Polymerization of vesicles gave stable polymeric vesicles. The results from the crosslinking and redox polymerization studies on 2-D assemblies were applied to the inverted hexagonal and bicontinuous cubic phases. Phase behavior is characterized before and after crosslinking polymerization principally by variable temperature ³¹NMR. γ-Initiated polymerization of bis-lipids was studied to evaluate their sensitivity to ionizing radiation. The reactive moiety effects the initial rate of polymerization, extent of polymerization, and inhibition by oxygen. A preliminary investigation of polymerizable ion-paired amphiphiles (IPA) showed polymerization methods commonly used for zwitterionic lipids can be applied to IPA. This is the first report of polymerization of reactive groups in the anionic acyl chain of an ion-paired amphiphile.
25
Miller, Thomas Jerome. „Comparing microwave induced polymerization to thermal induced polymerization of the resin bisphenol A-glycidyl methacrylate“. College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1520.
Annotation:
Thesis (M.S.) -- University of Maryland, College Park, 2004.Thesis research directed by: Dept. of Electrical and Computer Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
26
Thongnuanchan, Bencha. „A low temperature alkoxyamine designed for use in nitroxide-mediated miniemulsion polymerization“. Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/a-low-temperature-alkoxyamine-designed-for-use-in-nitroxidemediated-miniemulsion-polymerization(9dddd46a-9756-41a2-8b66-66fac7d360c9).html.
Annotation:
The basis for this research project is based on the discovery in the previous research that 2,2' ,5-trimethyl-3-( I-phenylethoxy)-4-tert-butyl-3-azahexane, (Styryl- TITNO) is able to control bulk polymerization of styrene at temperature as low as 70°C. The principle objective of this project was to evaluate the feasibility of using Styryl- TITNO to control radical solution and miniemulsion polymerizations at temperatures below 100°C. Styryl- TITNO was shown to effect solution polymerizations of both n-butyl acrylate (BA) and styrene below 100°C. Polymerization temperature was shown to be a crucial parameter for achieving control in Styryl- TITNO -mediated polymerizations. Good control of the number-average molecular weight (Mn) and molecular weight dispersity for the polymerization of BA was observed at 90°C. However, a lower temperature of 70 °C is required for good control of styrene polymerization. Living characteristics of polymer chains were demonstrated by a sequential chain extension of TITNO -terminated PBA with styrene at 90°C to form poly(n-butyl acrylate)- block-poly[(n-butyl acrylate)-co-styrene], [pBA-b-P(BA-co-PS)], block copolymers. An improvement in livingness in these reactions was observed when the second P(BAlstyrene) block was formed at 70°C after the first PBA block was produced at 90°C. Kinetics studies facilitated determination of the activation-deactivation equilibrium constant (K), which for styrene polymerization at 90°C (K = 4.1 x 10.9 mol L-J at 90°C and 3.0 x 10-9 mol L-J at 70 "C) is nearly an order of magnitude higher than that for BA polymerization at the same temperature (K = 8.5 x 10-11 mol L-I). This is the reason why BA polymerization shows better control than styrene polymerization at 90°C. The activation energy (Ea) for thermolysis of Stryl- TITNO is 104.1 kJ mol", which is relatively low compared to the literature values of Ea for various styryl alkoxymines. This explains why Styryl- TITNO is able to effect polymerization at temperatures as low as 70 "C. The studies of Styryl- TITNO-mediated miniemulsion polymerizations at 90 "C indicate that accumulation of free TITNO• in the particles is an issue for use of Styryl- TITNO in miniemulsion polymerizations. The use of L-ascorbic acid (L-AA) and L-ascorbic acid 6-palmitate (L-AAP) as nitroxide scavengers to reduce the level of free TITNO • in the polymerization was investigated. The best result was observed for the polymerization of BA in the presence of 5.35 mol% of L-AAP relative to Styryl- TITNO, which attained 48% conversion after 5 h. The chain extension of isolated TITNO -terminated PBA, TITNO -PBA, was used to examine the livingness of - polymer -chains before the rate of polymerization was severely retarded. The livingness of TITNO-PBA was evidenced by a shift of the staring PBA molecular weight distribution towards higher molecular weight, which provides solid evidence that the majority of polymer chains remained living. Thus, it can be concluded with certainty that the accumulation of free TITNO• was mainly responsible for the suppression of polymerization in miniemulsion polymerizations mediated by Styryl- TITNO.
27
Valente, Andreia. „Lanthanide based coordinative chain transfer polymerization for architecture control in (co)polymers and ruthenium catalyzed ring-opening polymerization : two aspects of atom economy in polymerization catalysis“. Thesis, Lille 1, 2010. http://www.theses.fr/2010LIL10061.
Annotation:
Le nouveau complexe Cp*La(BH4)2(THF)2 a été utilisé en combinaison avec des alkyles magnésiens et aluminiques pour la (co)polymérisation coordinative par transfert de chaîne (CCTP) du styrène et de l’isoprène. En développant ce concept nous avons obtenu la première croissance de chaîne catalysée du styrène et de l’isoprène avec contrôle de la microstructure. L’application de la CCTP à la copolymérisation statistique est une voie nouvelle et originale pour le contrôle de la composition de copolymères.Par ailleurs, une étude mécanistique a été réalisée pour la polymérisation de l’ ε-caprolactone avec des dérivés cationiques de ruthénium [(η5-C5H5)Ru(η6-arène substitué)][PF6]. Nous avons montré que la polymérisation a lieu selon un mécanisme de type monomère activé avec transfert aux alcools, avec modification de l’hapticité du ligand arèneA newly synthesized Cp*La(BH4)2(THF)2 complex in combination with magnesium or aluminum alkyls was used for the coordinative chain transfer (co)polymerization (CCTP) of styrene and isoprene. Using this concept, we have accomplished the first catalyzed chain growth like reaction of styrene and isoprene, with control of the microstructure. The application of CCTP to statistical copolymerization represents a new and original approach to tune the composition of copolymers. In addition, a mechanistic study of the ring-opening polymerization of ε-caprolactone by [(η5-C5H5)Ru(η6-substituted arene)][PF6] complexes shows that the polymerization proceeds via an activated monomer mechanism by transfer to the alcohol with a change of hapticity of the arene ligand
28
Samer, Charles J. „Dynamic modeling of continuous miniemulsion polymerization reactors“. Thesis, Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/10228.
29
Shoaf, Glenn Lewis. „Feasibility study for continuous emulsion copolymerization of ethyl acrylate and methacrylic acid“. Thesis, Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/10254.
30
Fontenot, Kevin. „Nucleation and growth in mini/macro emulsion polymerization systems“. Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/10922.
31
Mead, Richard Norman. „Emulsion copolymerization in continuous reactors“. Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/11030.
32
Azmus, Dora J. Taylor. „Synthesis of polybenzimidazoles from monomers containing flexible linkages“. Thesis, Corvallis, Oregon : Oregon State University, 1992. http://handle.dtic.mil/100.2/ADA256976.
Annotation:
Thesis (M.S.)--Oregon State University, 1993.Description based on title screen as viewed on April 8, 2009. "Completed 13 May 1992, Commencement June 1993." Includes bibliographical references (p. 73-75). Also available in print.
33
Plummer, Ronda. „Living polymerization of novel hydrophilic polymers /“. [St. Lucia, Qld.], 2005. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19201.pdf.
34
Matthews, Jermey N. A. „Thermodynamics and relaxation during actin polymerization“. College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2346.
Annotation:
Thesis (Ph. D.) -- University of Maryland, College Park, 2005.Thesis research directed by: Chemical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
35
Ha, Seung-kyu. „Starch incorporated polymerization of thermoplastic polyurethan“. [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965659852.
36
Ali, Mir Mukkaram Stöver Harald D. H. „Polymer capsules by living radical polymerization /“. *McMaster only, 2004.
37
Vardareli, Tugba. „Polymerization And Characterization Of Allyl Methacrylate“. Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607469/index.pdf.
Annotation:
Allyl methacrylate, AMA was polymerized by chemical initiator and by γ
-radiation under different conditions. The polymer obtained is mostly gel type with some soluble fractions at lower conversions. Arrhenius activation energy is 82.3 kJ/mol for chemical initiated polymerization. The polymer was characterized by FT-IR, NMR, DSC, TGA, XPS, XRD, DLS, and MS methods. It was found that about 98-99% of allyl side groups retained as pendant even after completion of the polymerization, while 1-2% may give crosslinking and/or cyclization that yields lactones and anhydrides. The spectroscopic and thermal results of the work showed that the reaction is not cyclopolymerization, but may have end group cyclization. Molecular weight of 1.1x106 was measured by DLS. Therefore, insolubility is due to the high molecular weight of polymer, even in the early stage of polymerization rather than crosslinking. The Tg of PAMA was observed as 94º
C before curing, upon curing at 150-200º
C, Tg increased to 211º
C as measured by DSC. The thermal treatment of polymer at about 350º
C gave anhydride by linkage type degradation, following side group cyclization. The XPS analysis showed the presence of radical fragments of AIBN and CCl4 associated with oligomers. The MS and TGA thermograms showed two or three stage degradations depending on solubility. The first stage was mostly linkage type degradation for the fragmentation of pendant allyl groups at 225-350º
C. In the second stage, at 395-515º
C, the degradation is random scission and depolymerization.
38
Kozanoglu, Selin. „Polymerization And Charaterization Of N-vinylcaprolactam“. Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609947/index.pdf.
Annotation:
Poly(N-vinylcaprolactam), PNVCL, is a nonionic, nontoxic, water soluble, thermally
sensitive and biocompatible polymer. It contains hydrophilic carboxylic and amide
groups with hydrophobic carbon-carbon backbone chain so its hydrolysis does not
produce small amide compounds which are often not desired for biomedical
applications. Moreover PNVCL possesses lower critical solution temperature,
(LCST) in the range of physiological temperature (32-34 oC). These properties make
the polymer suitable for use in some biotechnology applications such as implantation
of artificial organs and tissues, purification of enzymes, proteins and living cells, and
in drug release systems.
In this study PNVCL was synthesized by free radical polymerization with solution
technique. Polymerization was done at different temperatures for different time
periods in an oil bath. The activation energy for polymerization was found from
Arrhenius plot as 108.4 kJ/mol. Polymer was characterized by FT-IR, 1H-NMR and
13C-NMR, DSC, TGA and XRD techniques. FT-IR and NMR measurements
confirmed that the polymerization proceeded through the vinyl group.
39
Nozari, Samira. „Towards understanding RAFT aqueous heterophase polymerization“. Phd thesis, Universität Potsdam, 2005. http://opus.kobv.de/ubp/volltexte/2005/580/.
Annotation:
Reversible addition-fragmentation transfer (RAFT) was used as a controlling technique for studying the aqueous heterophase polymerization. The polymerization rates obtained by calorimetric investigation of ab initio emulsion polymerization of styrene revealed the strong influence of the type and combination of the RAFT agent and initiator on the polymerization rate and its profile. The studies in all-glass reactors on the evolution of the characteristic data such as average molecular weight, molecular weight distribution, and average particle size during the polymerization revealed the importance of the peculiarities of the heterophase system such as compartmentalization, swelling, and phase transfer. These results illustrated the important role of the water solubility of the initiator in determining the main loci of polymerization and the crucial role of the hydrophobicity of the RAFT agent for efficient transportation to the polymer particles. For an optimum control during ab-initio batch heterophase polymerization of styrene with RAFT, the RAFT agent must have certain hydrophilicity and the initiator must be water soluble in order to minimize reactions in the monomer phase.
An analytical method was developed for the quantitative measurements of the sorption of the RAFT agents to the polymer particles based on the absorption of the visible light by the RAFT agent. Polymer nanoparticles, temperature, and stirring were employed to simulate the conditions of a typical aqueous heterophase polymerization system. The results confirmed the role of the hydrophilicity of the RAFT agent on the effectiveness of the control due to its fast transportation to the polymer particles during the initial period of polymerization after particle nucleation. As the presence of the polymer particles were essential for the transportation of the RAFT agents into the polymer dispersion, it was concluded that in an ab initio emulsion polymerization the transport of the hydrophobic RAFT agent only takes place after the nucleation and formation of the polymer particles. While the polymerization proceeds and the particles grow the rate of the transportation of the RAFT agent increases with conversion until the free monomer phase disappears.The degradation of the RAFT agent by addition of KPS initiator revealed unambigueous evidence on the mechanism of entry in heterophase polymerization. These results showed that even extremely hydrophilic primary radicals, such as sulfate ion radical stemming from the KPS initiator, can enter the polymer particles without necessarily having propagated and reached a certain chain length. Moreover, these results recommend the employment of azo-initiators instead of persulfates for the application in seeded heterophase polymerization with RAFT agents.
The significant slower rate of transportation of the RAFT agent to the polymer particles when its solvent (styrene) was replaced with a more hydrophilic monomer (methyl methacrylate) lead to the conclusion that a complicated cooperative and competitive interplay of solubility parameters and interaction parameter with the particles exist, determining an effective transportation of the organic molecules to the polymer particles through the aqueous phase. The choice of proper solutions of even the most hydrophobic organic molecules can provide the opportunity of their sorption into the polymer particles. Examples to support this idea were given by loading the extremely stiff fluorescent molecule, pentacene, and very hydrophobic dye, Sudan IV, into the polymer particles.
Finally, the first application of RAFT at room temperature heterophase polymerization is reported. The results show that the RAFT process is effective at ambient temperature; however, the rate of fragmentation is significantly slower. The elevation of the reaction temperature in the presence of the RAFT agent resulted in faster polymerization and higher molar mass, suggesting that the fragmentation rate coefficient and its dependence on the temperature is responsible for the observed retardation.
Um neue Materialien mit außergewöhnlichen Eigenschaften zu erstellen, muss man in der Lage sein, die Struktur der Moleküle zu kontrollieren, aus denen die Materialien bestehen. Für das Maßschneidern solcher neuer Eigenschaften besitzen Polymere ein großes Potenzial: Dies sind sehr lange Moleküle, die aus einer großen Zahl von kleineren Einheiten aufgebaut sind. Proteine und DNS sind Beispiele für natürliche Polymere; Plastik und Gummi sind Beispiele für künstliche Polymere. Letztere werden üblicherweise durch das Zusammenfügen einer Reihe von kleineren Molekülen, den Monomeren, hergestellt. Schon lange versuchen Wissenschaftler, die Anordnung, Anzahl und Art dieser Monomere zu kontrollieren, die sich in der Struktur der Polymermoleküle widerspiegeln. Die gebräuchlichste Methode zur kommerziellen Produktion von Polymeren ist die so genannte freie radikalische Polymerisation. Die Strukturkontrolle durch diese Methode ist jedoch relativ schwierig und wurde maßgeblich erst im letzten Jahrzehnt entwickelt. Trotz der Existenz einiger effektiver Kontrollmethoden ist ihre industrielle Anwendung bislang sehr beschränkt, weil sie nicht für die Emulsionspolymerisation verwendbar sind. Die Emulsionspolymerisation ist die gängigste Technik in der industriellen Produktion von Polymeren. Es handelt sich dabei um ein vergleichsweise umweltfreundliches Verfahren, denn es werden keine organischen Lösungsmittel verwendet. Stattdessen dient Wasser als Lösungsmittel, in dem die Polymere in Form von kleinen, fein verteilten Partikeln vorliegen. In der Natur kommt dieses Prinzip beispielsweise in Pflanzen bei der Bildung von Kautschuk - allgemein als Latex bezeichnet - vor. Schließlich ist die Emulsionspolymerisation einfach durchzuführen: Das Produkt ist in vielen Fällen gebrauchsfertig, und es gibt viele technische Vorteile im Vergleich zu anderen Herstellungsprozessen.
Doch bevor die Probleme beim Einsatz von Kontrollmethoden in der Emulsionspolymerisation gelöst werden können, müssen erst ihre Ursachen geklärt werden. Dies ist eine unverzichtbare Vorraussetzung zum Übertragen von Forschungsergebnissen auf das tägliche Leben.
Ziel dieser Arbeit ist die Untersuchung der Probleme, die für die kontrollierte radikalische Polymerisation in Emulsion von Bedeutung sind. Die wichtigste Fragestellung in der Emulsionspolymerisation zielt auf die Löslichkeit der Reaktionskomponenten in den verschiedenen Phasen, wie z.B. in Wasser oder in den Polymerpartikeln. Die Kontrollmethode der Wahl für diese Arbeit ist "Reversibler Additions-Fragmentierungs Transfer" (RAFT). Die RAFT-Methode ist die modernste Kontrollmethode, und sie ist für viele Reaktionsbedingungen und viele Arten von Monomeren anwendbar.
40
Chen, Jianxin. „Cinnamated PDMS Polymerization for MEMS Applications“. Fogler Library, University of Maine, 2008. http://www.library.umaine.edu/theses/pdf/ChenJ2008.pdf.
41
LaFratta, Christopher N. „Multiphoton absorption polymerization issues and solutions /“. College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/4091.
Annotation:
Thesis (Ph. D.)--University of Maryland, College Park, 2006.Thesis research directed by: Chemistry. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
42
Wang, Aileen Ruiling Zhu Shiping. „Diffusion-controlled atom transfer radical polymerization“. *McMaster only, 2005.
43
Holmgren, Anders. „Biochemical Control Aspects in Lignin Polymerization“. Doctoral thesis, Stockholm Stockholm : KTH, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4632.
44
Weng, Weijun Ferrone Frank A. „Universal metastability of sickle hemoglobin polymerization /“. Philadelphia, Pa. : Drexel University, 2008. http://hdl.handle.net/1860/2832.
45
Chern, Chorng-Shyan. „Polymerization in non-uniform latex particles“. Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/12170.
46
Huang-Hobbs, Helen. „Dissecting the mechanism of ETV6 polymerization“. Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/45691.
Annotation:
ETV6 (or TEL), a member of the ETS family of eukaryotic transcription factors, normally functions as a transcriptional repressor and putative tumor suppressor. ETV6 is modular, containing a SAM (or PNT) domain and a DNA-binding ETS domain joined by a flexible linker sequence. The ETV6 SAM domain self-associates in a head-to-tail fashion, forming helical polymers proposed to generate extended repressive complexes at target DNA sites. ETV6 is also frequently involved in chromosomal translocations yielding unregulated chimeric oncoproteins with the SAM domain fused to the catalytic domain of a tyrosine receptor kinase such as NTRK3. Cellular transformation likely results from SAM domain-mediated polymerization and constitutive activation of the kinase domain. In the case of the ETV6- NTRK3 fusion (EN), this transformation is linked to congenital fibrosarcomas. Our goal is to investigate via mutations within its SAM domain, the thermodynamic and dynamic mechanisms underlying the altered transformation properties of ETV6-NTRK3. These studies have been carried out using monomeric variants of the isolated SAM domains with "head" or "tail" point mutations that prevent self-association, yet allow for formation of a mixed dimer with a native binding interface. Specifically, we used a combination of NMR spectroscopy and isothermal titration calorimetry to study the effects of additional mutations on their dimerization. Consistent with its involvement in a crystallographically-observed interdomain salt bridge, mutation of Lys99 was found to weaken the association of ETV-SAM monomers in solution, and to disrupt cellular transformation by EN. This supports the role of the SAM domain self-association in the activation of ETV6-NTRK3, and helps define the mechanisms underlying cellular transformation by similar chimeric oncoproteins.
47
Carrel, Hyman A. (Hyman Andrew) 1979. „Giant vesicles compressed by actin polymerization“. Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/16646.
Annotation:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Physics, 2004.Includes bibliographical references (p. 45-46).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Actin polymerization plays a critical role in generating propulsive force to drive many types of cell motility. The discovery of actin based motility of the bacterial pathogen Listeria monocytogenes has lead to clearer understandings of the essential ingredients required for cell motility. The biophysical mechanisms by which these proteins generate forces is the subject of intense investigation. A novel system to study force generation by this polymerization engine is introduced by combining the well characterized mechanical properties of synthetic Giant Vesicles with the well understood biochemistry of actin polymerization. Giant Vesicles mimic the structural features of eukaryotic cell membranes. We find that Giant Vesicles coated with a protein that catalyzes actin polymerization form thick actin shells which produce a compressive force. The polymerization force directed at the membrane interface causes the membrane to rupture. In the resulting collapse we find that the shell thickens inward with a constant radial velocity and is characterized by radial lines of lipid and actin. We show that actin polymerization is the primary force driving the collapse.
by Hyman A. Carrel.
S.M.
48
Klumperman, Bert. „NMR studies of radical polymerization processes“. Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71596.
Annotation:
Thesis (DSc)--Stellenbosch University, 2012.ENGLISH ABSTRACT: Examples of the use of NMR spectroscopy in the study of radical polymerization processes have been described. The studies presented have made a significant contribution to the understanding of the fundamental mechanistic processes in these polymerization systems. It is pointed out that NMR in conventional radical polymerization is of limited use due to the concurrent occurrence of all elementary reactions (initiation, propagation and termination). Conversely, for living radical polymerization, NMR has great value. In that case, the elementary reactions are somewhat more restricted to specific times of the polymerization process. This allows for example the detailed study of the early stages of chain growth in Reversible Addition-‐Fragmentation Chain Transfer (RAFT) mediated polymerization. Two different studies are described. The first is related to the early stages of RAFT-‐mediated polymerization. A process for which we coined the name initialization was studied via in situ 1H NMR spectroscopy. It is shown that in many cases, there is a selective reaction that converts the original RAFT agent into its single monomer adduct. A few different examples and their mechanistic interpretation are discussed. It is also shown that NMR spectroscopy can be a valuable tool for the assessment of a RAFT agent in conjunction with a specific monomer and polymerization conditions. In the second study, 15N NMR, 31P NMR and 1H NMR are used for two different types of experiments. The first is a conventional radical copolymerization in which the growing chains are trapped by a 15N labeled nitroxide to yield a stable product. In the second experiment, a similar copolymerization is conducted under nitroxide-‐mediated conditions. The nitroxide of choice contains phosphorous, which enables the quantification of the terminal monomer in the dormant chains. Each of the experiments individually provides interesting information on conventional radical copolymerization and nitroxide-‐mediated copolymerization, respectively. Combination of the experimental data reveals an interesting discrepancy in the ratio of terminal monomer units in active chains and dormant chains. Although not unexpected, this result is interesting and useful from a mechanistic as well as a synthetic point of view. In terms of future perspectives, it is expected that the advanced analytical techniques as described here will remain crucial in polymer science. Present developments in radical polymerization, such as investigations into monomer sequence control, rely on accurate knowledge of kinetic and mechanistic details of elementary reactions. It is expected that such detailed studies will be a main challenge for the next decade of polymer research.
AFRIKAANSE OPSOMMING: Voorbeelde van die gebruik van KMR-‐spektroskopie in die studie van radikaalpolimerisasies word beskryf. Hierdie studies het ʼn beduidende bydrae gelewer tot die verstaan van die fundamentele meganistiese prosesse in hierdie polimerisasiesisteme. Dit het daarop gewys dat KMR beperkte gebruike het in konvensionele radikaalpolimerisasies as gevolg van die gelyktydige voorkoms van alle basiese reaksies (afsetting, voortsetting en beëindiging). Aan die anderkant het KMR groot waarde vir lewende radikaalpolimerisasie. In hierdie geval is die elementêre reaksies ietwat meer beperk tot spesifieke tye van die polimerisasieproses. Gedetailleerde studies kan byvoorbeeld van die vroeë stadiums van die kettinggroei in Omkeerbare Addisie-‐Fragmentasie-‐ KettingOordrag (OAFO)-‐bemiddelde polimerisasie gedoen word. Twee verskillende studies is beskryf. Die eerste het betrekking op die vroeë stadiums van die OAFO-‐bemiddelde polimerisasie. 'n Proses wat “inisialisering” genoem is, is bestudeer deur middel van in situ 1H KMR-‐spektroskopie. Dit is bewys dat daar in baie gevalle 'n selektiewe reaksie is wat die oorspronklike OAFO-‐agent in sy enkelmonomeeradduk verander voor polimerisasie. 'n Paar ander voorbeelde en hul meganistiese interpretasie is bespreek. Dit is ook bewys dat KMR-‐spektroskopie 'n waardevolle hulpmiddel kan wees vir die assessering van 'n OAFO-‐agent in samewerking met 'n spesifieke monomeer en polimerisasie toestande. In die tweede studie is 15N KMR, 31P KMR en 1H KMR gebruik vir twee verskillende tipes van die eksperiment. Die eerste is 'n konvensionele radikaalkopolimerisasie waarin die groeiende kettings vasgevang word deur 'n 15N-‐gemerkte nitroksied om 'n stabiele produk te lewer. In die tweede eksperiment is 'n soortgelyke kopolimerisasie gedoen onder nitroksied-‐ bemiddelde toestande. Die gekose nitroksied bevat fosfor wat die kwantifisering van die terminale monomeer in die dormante kettings moontlik maak. Elkeen van die individuele eksperimente lewer interessante inligting oor konvensionele radikale kopolimerisasie en nitroksied-‐bemiddelde kopolimerisasie, onderskeidelik. ʼn Kombinasie van die eksperimentele data toon 'n interessante verskil aan in die verhouding van die terminale monomeereenhede in die aktiewe en sluimerende kettings. Alhoewel dit nie onverwags is nie, is die resultate interessant en van waarde vanuit 'n meganistiese-‐ sowel as 'n sintetiese oogpunt. In terme van toekomstige perspektiewe word daar verwag dat gevorderde analitiese tegnieke soos hier beskryf, belangrik sal bly in polimeerwetenskap. Huidige ontwikkelinge in radikaalpolimerisasie, soos ondersoeke na die beheer van monomeervolgorde, maak staat op akkurate kennis van kinetiese en meganistiese besonderhede van die basiese reaksies. Daar word verwag dat sulke gedetailleerde studies ʼn uitdaging sal bied vir die volgende dekade van polimeernavorsing.
49
Schütze, Mike. „Bimetallic Complexes for Cooperative Polymerization Catalysis“. Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://hdl.handle.net/11858/00-1735-0000-002E-E4A0-A.
50
Summers, Mark James. „Polymerization of nano-structured surfactant assemblies“. Thesis, University of Bristol, 2002. http://hdl.handle.net/1983/e4abbe4b-807c-462f-acdf-dceb786d55d7.