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Journal articles on the topic 'Polymerization mechanisms'

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Author: Grafiati

Published: 4 June 2021

Last updated: 20 February 2023

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1

Chen, Mao, Honghong Gong, and Yu Gu. "Controlled/Living Radical Polymerization of Semifluorinated (Meth)acrylates." Synlett 29, no. 12 (April 18, 2018): 1543–51. http://dx.doi.org/10.1055/s-0036-1591974.

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Fluorinated polymers are important materials for applications in many areas. This article summarizes the development of controlled/living radical polymerization (CRP) of semifluorinated (meth)acrylates, and briefly introduces their reaction mechanisms. While the classical CRP such as atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer (RAFT) polymerization and nitroxide-mediated radical polymerization (NMP) have promoted the preparation of semifluorinated polymers with tailor-designed architectures, recent development of photo-CRP has led to unprecedented accuracy and monomer scope. We expect that synthetic advances will facilitate the engineering of advanced fluorinated materials with unique properties.1 Introduction2 Atom Transfer Radical Polymerization3 Reversible Addition-Fragmentation Chain Transfer Polymerization4 Nitroxide-Mediated Radical Polymerization5 Photo-CRP Mediated with Metal Complexes6 Metal-free Photo-CRP7 Conclusion

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2

Penczek, Stanislaw, Julia Pretula, and Stanislaw Slomkowski. "Ring-opening polymerization." Chemistry Teacher International 3, no. 2 (March 15, 2021): 33–57. http://dx.doi.org/10.1515/cti-2020-0028.

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Abstract Ring-opening polymerization is defined by IUPAC (Penczek, S., Moad, G. (2008). Glossary of the terms related to kinetics, thermodynamics, and mechanisms of polymerization. (IUPAC Recommendations 2008), Pure and Applied Chemistry, 80(10), 2163–2193) as (cit.) “Ring-opening polymerization (ROP): Polymerization in which a cyclic monomer yields a monomeric unit that is either acyclic or contains fewer rings than the cyclic monomer”. The large part of the resulting polymerizations is living/controlled; practically all belong to chain polymerizations. After the introduction, providing basic information on chain polymerizations, the paper presents the concise overview of major classes of monomers used in ROP, including cyclic ethers, esters, carbonates, and siloxanes as well as cyclic nitrogen, phosphorus, and sulfur containing monomers. There are discussed also thermodynamics, kinetic polymerizability, and major mechanisms of ROP. Special attention is concentrated on polymers prepared by ROP on industrial scale.

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3

Prescott, S. W., M. J. Ballard, E. Rizzardo, and R. G. Gilbert. "RAFT in Emulsion Polymerization: What Makes it Different?" Australian Journal of Chemistry 55, no. 7 (2002): 415. http://dx.doi.org/10.1071/ch02073.

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Reversible addition-fragmentation chain transfer (RAFT) polymerization techniques have been the focus of a great deal of recent work, particularly in their application to emulsion polymerization, which is the method of choice for implementing most free-radical polymerizations on an industrial scale. RAFT/emulsion polymerizations have considerable technical potential: to 'tailor-make' material properties, to eliminate added surfactant from surface coatings, and so on. However, considerable difficulties have been experienced in using RAFT in emulsion polymerization systems. Here, progress in the application of RAFT techniques to emulsion polymerization is reviewed, summarizing the difficulties that have been experienced and mechanisms that have been postulated to explain the observed behaviour. Possible origins of the difficulties in implementing RAFT in emulsion polymerizations include polymerization in droplets, water sensitivity of some RAFT agents, slow transport of highly hydrophobic RAFT agents across the water phase, and surface activity of some RAFT agents.

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4

Jug, Karl, and Andreas Poredda. "Polymerization mechanisms of propellanes." Journal of the American Chemical Society 113, no. 3 (January 1991): 761–64. http://dx.doi.org/10.1021/ja00003a005.

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5

Save, Maud, Yohann Guillaneuf, and Robert G. Gilbert. "Controlled Radical Polymerization in Aqueous Dispersed Media." Australian Journal of Chemistry 59, no. 10 (2006): 693. http://dx.doi.org/10.1071/ch06308.

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Controlled radical polymerization (CRP), sometimes also termed ‘living’ radical polymerization, offers the potential to create a wide range of polymer architectures, and its implementation in aqueous dispersed media (e.g. emulsion polymerization, used on a vast scale industrially) opens the way to large-scale manufacture of products based on this technique. Until recently, implementing CRP in aqueous dispersed media was plagued with problems such as loss of ‘living’ character and loss of colloidal stability. This review examines the basic mechanistic processes in free-radical polymerization in aqueous dispersed media (e.g. emulsion polymerization), and then examines, through this mechanistic understanding, the new techniques that have been developed over the last few years to implement CRP successfully in emulsion polymerizations and related processes. The strategies leading to these successes can thus be understood in terms of the various mechanisms which dominate CRP systems in dispersed media; these mechanisms are sometimes quite different from those in conventional free-radical polymerization in these media.

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6

Pugh, Coleen, and Krzysztof Matyjaszewski. "Comparison of living polymerization mechanisms. Acrylates and carbocationic polymerization." Makromolekulare Chemie. Macromolecular Symposia 67, no. 1 (March 1993): 67–82. http://dx.doi.org/10.1002/masy.19930670106.

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7

Chern, C. S. "Emulsion polymerization mechanisms and kinetics." Progress in Polymer Science 31, no. 5 (May 2006): 443–86. http://dx.doi.org/10.1016/j.progpolymsci.2006.02.001.

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8

Chern, Chorng-Shyan, and Hsiu-Jung Tang. "Microemulsion polymerization kinetics and mechanisms." Journal of Applied Polymer Science 97, no. 5 (2005): 2005–13. http://dx.doi.org/10.1002/app.21673.

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9

Cruz, G. J., L. M. Gómez, M. Gonzalez-Torres, F. Gonzalez-Salgado, R. Basurto, E. Colín, J. C. Palacios, and M. G. Olayo. "Polymerization mechanisms in plasma polyallylamine." Journal of Materials Science 52, no. 2 (September 21, 2016): 1005–13. http://dx.doi.org/10.1007/s10853-016-0396-4.

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10

Yuan, Ming, Dayun Huang, and Yixuan Zhao. "Development of Synthesis and Application of High Molecular Weight Poly(Methyl Methacrylate)." Polymers 14, no. 13 (June 28, 2022): 2632. http://dx.doi.org/10.3390/polym14132632.

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Poly(methyl methacrylate) (PMMA) is widely used in aviation, architecture, medical treatment, optical instruments and other fields because of its good transparency, chemical stability and electrical insulation. However, the application of PMMA largely depends on its physical properties. Mechanical properties such as tensile strength, fracture surface energy, shear modulus and Young’s modulus are increased with the increase in molecular weight. Consequently, it is of great significance to synthesize high molecular weight PMMA. In this article, we review the application of conventional free radical polymerization, atom transfer radical polymerization (ATRP) and coordination polymerization for preparing high molecular weight PMMA. The mechanisms of these polymerizations are discussed. In addition, applications of PMMA are also summarized.

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11

Krasilnikov, A. "Mechanisms of triplex-caused polymerization arrest." Nucleic Acids Research 25, no. 7 (April 1, 1997): 1339–46. http://dx.doi.org/10.1093/nar/25.7.1339.

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12

Tsavalas, John G., Yingwu Luo, and F. Joseph Schork. "Grafting mechanisms in hybrid miniemulsion polymerization." Journal of Applied Polymer Science 87, no. 11 (January 6, 2003): 1825–36. http://dx.doi.org/10.1002/app.11916.

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13

Tan, Y. Yong, and Ger Challa. "Template polymerization by free radical mechanisms." Makromolekulare Chemie. Macromolecular Symposia 10-11, no. 1 (October 1987): 215–33. http://dx.doi.org/10.1002/masy.19870100112.

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14

Nedeljkovic, Dragutin. "Polystyrene-b-Poly(2-(Methoxyethoxy)ethyl Methacrylate) Polymerization by Different Controlled Polymerization Mechanisms." Polymers 13, no. 20 (October 12, 2021): 3505. http://dx.doi.org/10.3390/polym13203505.

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Functional polymers have been an important field of research in recent years. With the development of the controlled polymerization methods, block-copolymers of defined structures and properties could be obtained. In this paper, the possibility of the synthesis of the functional block-copolymer polystyrene-b-poly(2-(methoxyethoxy)ethyl methacrylate) was tested. The target was to prepare the polymer of the number average molecular weight (Mn) of approximately 120 that would contain 20–40% of poly(2-(methoxyethoxy)ethyl methacrylate) by mass and in which the polymer phases would be separated. The polymerization reactions were performed by three different mechanisms for the controlled polymerization—sequential anionic polymerization, atomic transfer radical polymerization and the combination of those two methods. In sequential anionic polymerization and in atomic transfer radical polymerization block-copolymers of the desired composition were obtained but with the Mn significantly lower than desired (up to 30). The polymerization of the block-copolymers of the higher Mn was unsuccessful, and the possible mechanisms for the unwanted side reactions are discussed. It is also concluded that combination of sequential anionic polymerization and atomic transfer radical polymerization is not suitable for this system as polystyrene macroinitiator cannot initiate the polymerization of poly(2-(methoxyethoxy)ethyl methacrylate).

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15

Li, Yufang, David G. Ward, Srinivasa S. Reddy, and Scott Collins. "Polymerization of Methyl Methacrylate Using Zirconocene Initiators: Polymerization Mechanisms and Applications." Macromolecules 30, no. 7 (April 1997): 1875–83. http://dx.doi.org/10.1021/ma961472u.

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16

Yamaguchi, Takeo, Shin-Ichi Nakao, and Shoji Kimura. "Evidence and mechanisms of filling polymerization by plasma-induced graft polymerization." Journal of Polymer Science Part A: Polymer Chemistry 34, no. 7 (May 1996): 1203–8. http://dx.doi.org/10.1002/(sici)1099-0518(199605)34:7<1203::aid-pola6>3.0.co;2-3.

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17

Reddy, Sirish K., Neil B. Cramer, Michael Kalvaitas, Tai Yeon Lee, and Christopher N. Bowman. "Mechanistic Modelling and Network Properties of Ternary Thiol - Vinyl Photopolymerizations." Australian Journal of Chemistry 59, no. 8 (2006): 586. http://dx.doi.org/10.1071/ch06193.

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Ternary thiol–vinyl polymerizations offer a unique platform for improved control over polymerization kinetics and network properties as compared to both binary thiol–vinyl systems and traditional (meth)acrylic systems. Therefore, this study seeks to improve the fundamental understanding of the complex ternary thiol–vinyl systems to enable enhanced control over polymerization kinetics, network evolution, and, ultimately, network properties. The polymerization kinetics and material properties afforded by thiol–triazine–methacrylate systems are investigated. The ternary kinetics are successfully predicted by understanding the reaction mechanisms of the corresponding binary components. In ternary thiol–ene–(meth)acrylate systems, the variation in stoichiometric ratios of thiol and ene does not significantly impact material properties as in thiol–ene- or thiol–(meth)acrylate systems. Further, the ternary systems also provide unique polymer properties such as high glass transition temperature with narrow transition widths.

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18

Weisel, John W., and Rustem I. Litvinov. "Mechanisms of fibrin polymerization and clinical implications." Blood 121, no. 10 (March 7, 2013): 1712–19. http://dx.doi.org/10.1182/blood-2012-09-306639.

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Abstract Research on all stages of fibrin polymerization, using a variety of approaches including naturally occurring and recombinant variants of fibrinogen, x-ray crystallography, electron and light microscopy, and other biophysical approaches, has revealed aspects of the molecular mechanisms involved. The ordered sequence of fibrinopeptide release is essential for the knob-hole interactions that initiate oligomer formation and the subsequent formation of 2-stranded protofibrils. Calcium ions bound both strongly and weakly to fibrin(ogen) have been localized, and some aspects of their roles are beginning to be discovered. Much less is known about the mechanisms of the lateral aggregation of protofibrils and the subsequent branching to yield a 3-dimensional network, although the αC region and B:b knob-hole binding seem to enhance lateral aggregation. Much information now exists about variations in clot structure and properties because of genetic and acquired molecular variants, environmental factors, effects of various intravascular and extravascular cells, hydrodynamic flow, and some functional consequences. The mechanical and chemical stability of clots and thrombi are affected by both the structure of the fibrin network and cross-linking by plasma transglutaminase. There are important clinical consequences to all of these new findings that are relevant for the pathogenesis of diseases, prophylaxis, diagnosis, and treatment.

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19

Fan, Yan Li, Hao Jin, Xiao Hua Zhi, and Ya Fei Lu. "Kinetics of Supramolecular Polymerization: MSOA and HG Mechanisms." Advanced Materials Research 11-12 (February 2006): 639–42. http://dx.doi.org/10.4028/www.scientific.net/amr.11-12.639.

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Multistage open association (MSOA) and helical growth (HG) mechanisms describe the linear growth of supramolecular polymer chains and the helical growth of supramolecular chains with the intra-assemble cooperative effect, respectively. Both mechanisms were proposed by Ciferri. Assuming that supramolecular polymerization follows the step-growth and the interaction between repeat units is independent of molecular weight, the kinetics of MSOA and HG can be mathematically analyzed. In this paper the relationships among degree of polymerization (DP), unimer concentration (C0), and equilibrium constant (K) for MSOA and DP , concentration of helical polymer ( h C ), and nucleation factor (σ ) for HG were derived.

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20

Philipp, N., S. Angriman, S. Burne, P. Caral, I. Gómez Florenciano, N. Rapagnani, M. Gabriel, and L. C. Estrada. "Physico-chemical elucidation of the mechanism involved in optical lithography: Micro-fabrication of 2D and 3D platforms." Journal of Applied Physics 132, no. 18 (November 14, 2022): 183104. http://dx.doi.org/10.1063/5.0123862.

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Direct laser lithography has attracted much attention as a convenient micro-fabrication method to develop rapid, free-form, and low-cost microstructures. In this work, different microdevices were fabricated using a home-made two-photon excitation microscope and a commercial negative UV photoresin. The mechanism involved during the fabrication of the devices as well as the effects of the irradiation intensity and removal time on micro-patterns was investigated by optical microscopy. For the characterization of the microstructures, scanning electron microscopy, atomic force microscopy, Nuclear Magnetic Resonance (1H-NMR), and Fourier transform infrared spectroscopy were used. High-resolution optical characterization shows an enormous uniformity and high reproducibility of fabricated platforms in two and three dimensions. These results prompted us to propose a different mechanism not compatible with a polymerization reaction as the triggering mechanism for the interaction between light and the photoresin. We demonstrate the coexistence of an allylic photo-induced reaction with a photo-induced polymerization effect during the fabrication process. We studied the influence of these mechanisms by fabricating micro-patterns in two conditions, with and without the presence of a polymerization initiator [azobisisobutyronitrile (AIBN)], which boots the polymerization reaction. Even though the two mechanisms are present during the fabrication process, the polymerization is dominant in the presence of a photo-initiator as AIBN. Finally, we discuss the applications of our microdevices as suitable platforms for industry and biomedical applications.

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21

Yang, D. Billy. "Direct Kinetic Measurements of Vinyl Polymerization on Metal and Silicon Surfaces Using Real-Time FT-IR Spectroscopy." Applied Spectroscopy 47, no. 9 (September 1993): 1425–29. http://dx.doi.org/10.1366/0003702934067739.

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A real-time FT-IR (RT/FT-IR) technique has been used to perform direct kinetic measurements of vinyl polymerization on metal and silicon surfaces. Here, we are reporting our results in studies of anaerobic and photo-induced anionic polymerizations of monomers containing vinyl functional groups (>C=C<) for adhesive and coating applications. For anaerobic polymerization we are investigating the hydroperoxide-initiated free radical polymerization of model multifunctional methacrylate monomer systems. We will report the results of our studies on the catalytic effects of different dithiolate complexes and related accelerators. In photo-induced anionic polymerization we will report our studies for ethyl cyanoacrylate (CA) polymerization initiated by a controlled release of anion from a stable chromium complex precursor ( trans-Cr-(NH3)2(NCS)4−K+). Because of high surface sensitivity of the CA monomer, the polymerization kinetic studies were performed on a clean silicon surface at room temperature. The effect of the initiator concentration and irradiation wavelengths on polymerization kinetic rate will be discussed. The acrylic polymerization was monitored with the use of the C=C stretching band at 1634 and 1627 cm−1 for polyglycol dimethacrylate and cyanoacrylate, respectively. Both the degree of polymerization and the intrinsic rates of the polymerization reactions were calculated for kinetic comparisons. For anaerobic polymerization studies, GC/FT-IR software was used which provided a real-time screen display of IR spectral changes as the reaction proceeded. For very fast cyanoacrylate anionic polymerization studies, new FT-IR kinetic software was used to collect 204 spectra per minute with one spectrum per scan. In this case, the interferograms were collected first; post-Fourier transform conversion and spectral script reduction were then performed. Some detailed experimental techniques and polymerization reaction mechanisms will also be discussed.

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22

Garg, Puneet, Rakesh Verma, Deepak Nihalani, Duncan B. Johnstone, and Lawrence B. Holzman. "Neph1 Cooperates with Nephrin To Transduce a Signal That Induces Actin Polymerization." Molecular and Cellular Biology 27, no. 24 (October 8, 2007): 8698–712. http://dx.doi.org/10.1128/mcb.00948-07.

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ABSTRACT While the mechanisms that regulate actin dynamics in cellular motility are intensively studied, relatively little is known about signaling events that transmit outside-in signals and direct assembly and regulation of actin polymerization complexes at the cell membrane. The kidney podocyte provides a unique model for investigating these mechanisms since deletion of Nephrin or Neph1, two interacting components of the specialized podocyte intercellular junction, results in abnormal podocyte morphogenesis and junction formation. We provide evidence that extends the existing model by which the Nephrin-Neph1 complex transduces phosphorylation-mediated signals that assemble an actin polymerization complex at the podocyte intercellular junction. Upon engagement, Neph1 is phosphorylated on specific tyrosine residues by Fyn, which results in the recruitment of Grb2, an event that is necessary for Neph1-induced actin polymerization at the plasma membrane. Importantly, Neph1 and Nephrin directly interact and, by juxtaposing Grb2 and Nck1/2 at the membrane following complex activation, cooperate to augment the efficiency of actin polymerization. These data provide evidence for a mechanism reminiscent of that employed by vaccinia virus and other pathogens, by which a signaling complex transduces an outside-in signal that results in actin filament polymerization at the plasma membrane.

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23

Kabatc, Janina, Katarzyna Iwińska, Alicja Balcerak, Dominika Kwiatkowska, Agnieszka Skotnicka, Zbigniew Czech, and Marcin Bartkowiak. "Onium salts improve the kinetics of photopolymerization of acrylate activated with visible light." RSC Advances 10, no. 42 (2020): 24817–29. http://dx.doi.org/10.1039/d0ra03818k.

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The chemical mechanisms were investigated by steady state photolysis and nanosecond laser flash photolysis experiments. A mechanism for initiating polymerization using both onium salts is proposed here.

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24

Rentero, Christian, Jesús Damián, Asier Medel, María Fernández-Millán, Yolanda Rusconi, Giovanni Talarico, Tomás Cuenca, Valentina Sessini, and Marta E. G. Mosquera. "Ring-Opening Polymerization of L-Lactide Catalyzed by Potassium-Based Complexes: Mechanistic Studies." Polymers 14, no. 15 (July 23, 2022): 2982. http://dx.doi.org/10.3390/polym14152982.

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Two non-toxic potassium compounds, 1 and 2, with a commercial oximate ligand have been prepared and fully spectroscopically characterized. Their activity as catalysts for the ring-opening polymerization (ROP) process of LLA has been studied, showing that they are extremely active and able to polymerize the monomer in a few minutes. For derivative 2, the presence of a crown ether in the potassium coordination sphere affects the nuclearity of the compound and consequently its solubility, with both aspects having an influence in the polymerization process. Detailed studies of the polymerization mechanism have been performed, and an unusual anionic mechanism was observed in absence of a co-initiator. Indeed, the monomer deprotonation generates a lactide enolate, which initiates the polymerization propagation. On the contrary, when a 1:1 ratio of cat:BnOH is used, a mixture of mechanisms is observed, the anionic mechanism and the activated monomer one, while from a cat:BnOH ratio of 1:2 and over, only the activated monomer mechanism is observed.

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25

Giz, Ahmet, Huceste Çatalgil-Giz, Alina Alb, Jean-Luc Brousseau, and Wayne F. Reed. "Kinetics and Mechanisms of Acrylamide Polymerization from Absolute, Online Monitoring of Polymerization Reaction." Macromolecules 34, no. 5 (February 2001): 1180–91. http://dx.doi.org/10.1021/ma000815s.

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26

Margl, Peter. "Mechanisms for anionic butadiene polymerization with alkyl lithium species." Canadian Journal of Chemistry 87, no. 7 (July 2009): 891–903. http://dx.doi.org/10.1139/v09-032.

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Anionic butadiene polymerization by means of [Li-polybutadienyl]x species (x = 1–6, 8) without polar agents was investigated by means of density functional theory (DFT) under conditions relevant to industrial application, namely in a low-dielectric hydrocarbon solvent and at room temperature. The calculations indicate that the dimeric and tetrameric catalyst species together account for the bulk of Li-polybutadienyl species in the polymerization mixture under typical conditions. It is likely that each type of oligomer produces its own “fingerprint” signature polymer microstructure, as there is a systematic variation in the amounts of 1,2- and 1,4-insertions as well as in the preference of cis- and trans-butadiene. According to the calculations, higher aggregated Li species tend to produce more 1,2-insertions and prefer trans- over cis-butadiene insertion, while the dimer prefers trans-butadiene and 1,4-insertions. The dimer closely reproduces the experimentally observed polybutadiene microstructure (5%–10% 1,2-insertion, approximately equal ratios of cis and trans units with a slight predominance of trans). The monomeric catalyst species shows a clear preference for insertion of cis-butadiene over trans-butadiene. Thus, the monomer species is predicted to be present in the polymerization mixture in very small concentrations under normal conditions and the overall polymerization is predicted to be mainly carried out by the dimeric catalyst species.

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27

Njopwouo, D., G. Roques, and R. Wandji. "A contribution to the study of the catalytic action of clays on the polymerization of styrene: II. Reaction mechanism." Clay Minerals 23, no. 1 (March 1988): 35–43. http://dx.doi.org/10.1180/claymin.1988.023.1.04.

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AbstractThe study of 13C NMR spectra of polystyrene thermally obtained on clays shows that thermal polymerization of styrene on these minerals proceeds by two parallel reaction mechanisms: the radical mechanism due to the thermal effect, and the cationic mechanism in which the initiatory cation H+ is provided by the clay. The latter mechanism, accelerated by increase in temperature, becomes more important as the clay content increases in the reaction medium. Otherwise, the thermal polymerization on clays is accompanied by the hydrogenation of some α carbons of the polystyrene molecule and the oxidation of certain aromatic carbons.

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28

Skliutas, Edvinas, Migle Lebedevaite, Elmina Kabouraki, Tommaso Baldacchini, Jolita Ostrauskaite, Maria Vamvakaki, Maria Farsari, Saulius Juodkazis, and Mangirdas Malinauskas. "Polymerization mechanisms initiated by spatio-temporally confined light." Nanophotonics 10, no. 4 (January 1, 2021): 1211–42. http://dx.doi.org/10.1515/nanoph-2020-0551.

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Abstract Ultrafast laser 3D lithography based on non-linear light–matter interactions, widely known as multi-photon lithography (MPL), offers unrivaled precision rapid prototyping and flexible additive manufacturing options. 3D printing equipment based on MPL is already commercially available, yet there is still no comprehensive understanding of factors determining spatial resolution, accuracy, fabrication throughput, repeatability, and standardized metrology methods for the accurate characterization of the produced 3D objects and their functionalities. The photoexcitation mechanisms, spatial-control or photo-modified volumes, and the variety of processable materials are topics actively investigated. The complexity of the research field is underlined by a limited understanding and fragmented knowledge of light-excitation and material response. Research to date has only provided case-specific findings on photoexcitation, chemical modification, and material characterization of the experimental data. In this review, we aim to provide a consistent and comprehensive summary of the existing literature on photopolymerization mechanisms under highly confined spatial and temporal conditions, where, besides the excitation and cross-linking, parameters such as diffusion, temperature accumulation, and the finite amount of monomer molecules start to become of critical importance. Key parameters such as photoexcitation, polymerization kinetics, and the properties of the additively manufactured materials at the nanoscale in 3D are examined, whereas, the perspectives for future research and as well as emerging applications are outlined.

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29

Chen, Mao, Mingjiang Zhong, and Jeremiah A. Johnson. "Light-Controlled Radical Polymerization: Mechanisms, Methods, and Applications." Chemical Reviews 116, no. 17 (March 15, 2016): 10167–211. http://dx.doi.org/10.1021/acs.chemrev.5b00671.

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30

Sigwalt, Pierre, and Michel Moreau. "Carbocationic polymerization: Mechanisms and kinetics of propagation reactions." Progress in Polymer Science 31, no. 1 (January 2006): 44–120. http://dx.doi.org/10.1016/j.progpolymsci.2005.09.003.

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31

Yurtsever, Mine, and Ersin Yurtsever. "A DFT study of polymerization mechanisms of indole." Polymer 43, no. 22 (January 2002): 6019–25. http://dx.doi.org/10.1016/s0032-3861(02)00510-4.

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32

Davidson, T. A., K. B. Wagener, and D. B. Priddy. "Polymerization of Dicyclopentadiene: A Tale of Two Mechanisms." Macromolecules 29, no. 2 (January 1996): 786–88. http://dx.doi.org/10.1021/ma950852x.

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33

Morton, Maurice, L. J. Fetters, and E. E. Bostick. "Mechanisms of homogeneous anionic polymerization by alkyllithium initiators." Journal of Polymer Science Part C: Polymer Symposia 1, no. 1 (March 7, 2007): 311–23. http://dx.doi.org/10.1002/polc.5070010121.

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34

Matyjaszewski, Krzysztof. "Atom Transfer Radical Polymerization: From Mechanisms to Applications." Israel Journal of Chemistry 52, no. 3-4 (April 2012): 206–20. http://dx.doi.org/10.1002/ijch.201100101.

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35

Penczek, Stanislaw. "Terminology of kinetics, thermodynamics, and mechanisms of polymerization." Journal of Polymer Science Part A: Polymer Chemistry 40, no. 11 (April 23, 2002): 1665–76. http://dx.doi.org/10.1002/pola.10228.

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36

Asua, José M. "Emulsion polymerization: From fundamental mechanisms to process developments." Journal of Polymer Science Part A: Polymer Chemistry 42, no. 5 (January 12, 2004): 1025–41. http://dx.doi.org/10.1002/pola.11096.

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37

Gandini, Alessandro, Marie Christine Salon, Mekki Choura, Rachid El Gharbi, Hilmi Amri, and Zuen Hui. "Furan chemistry and ionic polymerization: Mechanisms and structures." Makromolekulare Chemie. Macromolecular Symposia 60, no. 1 (July 1992): 165–76. http://dx.doi.org/10.1002/masy.19920600115.

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38

Kashiwa, N., K. Soga, A. Zambelli, J. J. Eisch, R. F. Jordan, and M. Galimberti. "Panel discussion II molecular mechanisms of polymerization catalysis." Makromolekulare Chemie. Macromolecular Symposia 66, no. 1 (February 1993): 329–34. http://dx.doi.org/10.1002/masy.19930660128.

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39

Penczek, Stanislaw, and Andrzej Duda. "Kinetics and mechanisms in anionic ring-opening polymerization." Makromolekulare Chemie. Macromolecular Symposia 67, no. 1 (March 1993): 15–42. http://dx.doi.org/10.1002/masy.19930670104.

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40

Acharya, Udit, Patrycja Bober, Muhammed Arshad Thottappali, Zuzana Morávková, Magdalena Konefał, and Jiří Pfleger. "Synthesis and Impedance Spectroscopy of Poly(p-phenylenediamine)/Montmorillonite Composites." Polymers 13, no. 18 (September 16, 2021): 3132. http://dx.doi.org/10.3390/polym13183132.

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Poly(p-phenylenediamine)/montmorillonite (PPDA/MMT) composites were prepared by the oxidative polymerization of monomers intercalated within the MMT gallery, using ammonium peroxydisulfate as an oxidant. The intercalation process was evidenced by X-ray powder diffraction. The FT-IR and Raman spectroscopies revealed that, depending on the initial ratio between monomers and MMT in the polymerization mixture, the polymer or mainly oligomers are created during polymerization. The DC conductivity of composites was found to be higher than the conductivity of pristine polymer, reaching the highest value of 10−6 S cm−1 for the optimal MMT amount used during polymerization. Impedance spectroscopy was performed over wide frequency and temperature ranges to study the charge transport mechanism. The data analyzed in the framework of conductivity formalism suggest different conduction mechanisms for high and low temperature regions.

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41

Maletin, Aleksandra, Ivan Ristic, Tanja Veljovic, Bojana Ramic, Tatjana Puskar, Milica Jeremic-Knezevic, Daniela Djurovic Koprivica, Bojana Milekic, and Karolina Vukoje. "Influence of Dimethacrylate Monomer on the Polymerization Efficacy of Resin-Based Dental Cements—FTIR Analysis." Polymers 14, no. 2 (January 7, 2022): 247. http://dx.doi.org/10.3390/polym14020247.

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The degree of polymerization for dimethacrylate resin-based materials (BisGMA, TEGDMA, UDMA, HEMA) ranges from 55 to 75%. Literature data indicate that polymerization efficacy depends, among other factors, on the type of methacrylate resin comprising the material. The aim of this study was to evaluate the polymerization efficacy of four dental cement materials characterized by different polymerization mechanisms using FTIR analysis. In the present study, the FTIR method was adopted to analyze the degree of polymerization efficacy of four resin-based dental cement materials, two of which were self-cured and two were dual-cured cements. The IR spectral analysis was performed 24 h after the polymerization of the cementitious material. RelyX ARC cement exhibits the lowest polymerization efficacy (61.3%), while that of Variolink II (85.8%) and Maxcem Elite is the highest (90.1%). Although the efficacy of self-cured cements appears to be superior, the difference is not statistically significant (p = 0.280). Polymerization efficacy largely depends on the chemical structure of the material in terms of the presence of a particular methacrylate resin and less on the polymerization mechanism itself, i.e., whether it is a self-cured or dually cured dental cement. Thus, in clinical practice, cementitious materials with a higher proportion of TEGDMA compared with BisGMA are recommended.

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Song, Wenguang, Jian Huang, Cheng Hang, Chenyan Liu, Xuepu Wang, and Guowei Wang. "Synthesis of thermally cleavable multisegmented polystyrene by an atom transfer nitroxide radical polymerization (ATNRP) mechanism." Polymer Chemistry 6, no. 46 (2015): 8060–70. http://dx.doi.org/10.1039/c5py01493j.

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Based on the common features of well-defined NRC reaction, ATRP and NMRP mechanisms, an atom transfer nitroxide radical polymerization (ATNRP) mechanism was presented, and further used to construct multisegmented PS_m embedded with multiple alkoxyamine linkages.

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43

Zhang, Randi, Rong Gao, Qingqiang Gou, Jingjing Lai, and Xinyang Li. "Precipitation Polymerization: A Powerful Tool for Preparation of Uniform Polymer Particles." Polymers 14, no. 9 (April 30, 2022): 1851. http://dx.doi.org/10.3390/polym14091851.

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Precipitation polymerization (PP) is a powerful tool to prepare various types of uniform polymer particles owing to its outstanding advantages of easy operation and the absence of any surfactant. Several PP approaches have been developed up to now, including traditional thermo-induced precipitation polymerization (TRPP), distillation precipitation polymerization (DPP), reflux precipitation polymerization (RPP), photoinduced precipitation polymerization (PPP), solvothermal precipitation polymerization (SPP), controlled/‘‘living’’ radical precipitation polymerization (CRPP) and self-stabilized precipitation polymerization (2SPP). In this review, a general introduction to the categories, mechanisms, and applications of precipitation polymerization and the recent developments are presented, proving that PP has great potential to become one of the most attractive polymerization techniques in materials science and bio-medical areas.

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44

Zaccaria, Francesco, Peter H. M. Budzelaar, Cristiano Zuccaccia, Roberta Cipullo, Alceo Macchioni, Vincenzo Busico, and Christian Ehm. "Chain Transfer to Solvent and Monomer in Early Transition Metal Catalyzed Olefin Polymerization: Mechanisms and Implications for Catalysis." Catalysts 11, no. 2 (February 5, 2021): 215. http://dx.doi.org/10.3390/catal11020215.

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Even after several decades of intense research, mechanistic studies of olefin polymerization by early transition metal catalysts continue to reveal unexpected elementary reaction steps. In this mini-review, the recent discovery of two unprecedented chain termination processes is summarized: chain transfer to solvent (CTS) and chain transfer to monomer (CTM), leading to benzyl/tolyl and allyl type chain ends, respectively. Although similar transfer reactions are well-known in radical polymerization, only very recently they have been observed also in olefin insertion polymerization catalysis. In the latter context, these processes were first identified in Ti-catalyzed propene and ethene polymerization; more recently, CTS was also reported in Sc-catalyzed styrene polymerization. In the Ti case, these processes represent a unique combination of insertion polymerization, organic radical chemistry and reactivity of a M(IV)/M(III) redox couple. In the Sc case, CTS occurs via a σ-bond metathesis reactivity, and it is associated with a significant boost of catalytic activity and/or with tuning of polystyrene molecular weight and tacticity. The mechanistic studies that led to the understanding of these chain transfer reactions are summarized, highlighting their relevance in olefin polymerization catalysis and beyond.

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Schaeffer, Céline, Sara Santambrogio, Simone Perucca, Giorgio Casari, and Luca Rampoldi. "Analysis of Uromodulin Polymerization Provides New Insights into the Mechanisms Regulating ZP Domain-mediated Protein Assembly." Molecular Biology of the Cell 20, no. 2 (January 15, 2009): 589–99. http://dx.doi.org/10.1091/mbc.e08-08-0876.

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Uromodulin is the most abundant protein secreted in urine, in which it is found as a high-molecular-weight polymer. Polymerization occurs via its zona pellucida (ZP) domain, a conserved module shared by many extracellular eukaryotic proteins that are able to assemble into matrices. In this work, we identified two motifs in uromodulin, mapping in the linker region of the ZP domain and in between protein cleavage and glycosylphosphatidylinositol (GPI)-anchoring sites, which regulate its polymerization. Indeed, mutations in either module led to premature intracellular polymerization of a soluble uromodulin isoform, demonstrating the inhibitory role of these motifs for ZP domain-mediated protein assembly. Proteolytic cleavage separating the external motif from the mature monomer is necessary to release the inhibitory function and allow protein polymerization. Moreover, we report absent or abnormal assembly into filaments of GPI-anchored uromodulin mutated in either the internal or the external motif. This effect is due to altered processing on the plasma membrane, demonstrating that the presence of the two modules has not only an inhibitory function but also can positively regulate protein polymerization. Our data expand previous knowledge on the control of ZP domain function and suggest a common mechanism regulating polymerization of ZP domain proteins.

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Reinsch, S., and P. Gonczy. "Mechanisms of nuclear positioning." Journal of Cell Science 111, no. 16 (August 15, 1998): 2283–95. http://dx.doi.org/10.1242/jcs.111.16.2283.

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The mechanisms underlying two types of microtubule-dependent nuclear positioning are discussed. ‘MTOC-dependent nuclear positioning’ occurs when a nucleus is tightly associated with a microtubule organizing center (MTOC). ‘Nuclear tracking along microtubules’ is analogous to the motor-driven motility of other organelles and occurs when the nucleus lacks an associated MTOC. These two basic types of microtubule-dependent nuclear positioning may cooperate in many proliferating animal cells to achieve proper nuclear positioning. Microtubule polymerization and dynamics, motor proteins, MAPs and specialized sites such as cortical anchors function to control nuclear movements within cells.

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Lang, Margit, Stefan Hirner, Frank Wiesbrock, and Peter Fuchs. "A Review on Modeling Cure Kinetics and Mechanisms of Photopolymerization." Polymers 14, no. 10 (May 19, 2022): 2074. http://dx.doi.org/10.3390/polym14102074.

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Photopolymerizations, in which the initiation of a chemical-physical reaction occurs by the exposure of photosensitive monomers to a high-intensity light source, have become a well-accepted technology for manufacturing polymers. Providing significant advantages over thermal-initiated polymerizations, including fast and controllable reaction rates, as well as spatial and temporal control over the formation of material, this technology has found a large variety of industrial applications. The reaction mechanisms and kinetics are quite complex as the system moves quickly from a liquid monomer mixture to a solid polymer. Therefore, the study of curing kinetics is of utmost importance for industrial applications, providing both the understanding of the process development and the improvement of the quality of parts manufactured via photopolymerization. Consequently, this review aims at presenting the materials and curing chemistry of such ultrafast crosslinking polymerization reactions as well as the research efforts on theoretical models to reproduce cure kinetics and mechanisms for free-radical and cationic photopolymerizations including diffusion-controlled phenomena and oxygen inhibition reactions in free-radical systems.

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Pei, Shen, Daizheng Tu, Chenwei Wan, Juntong Yin, and Quan Yuan. "Preparation and applications of the polymeric micelle by polymerization-induced self-assembly (PISA)." Journal of Physics: Conference Series 2229, no. 1 (March 1, 2022): 012010. http://dx.doi.org/10.1088/1742-6596/2229/1/012010.

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Abstract Polymerization induced self-assembly (PISA) has a high solid content, simple operating steps, and can generally achieve high conversion to monomers in a short time, which has been widely used in the preparation and adjusting to morphologies of polymer micelles self-assembly. In this article, the preparation and applications of the polymeric micelle synthesized by PISA were reviewed. The particle morphology can be adjusted by a variety of active polymerizations with different initiation mechanisms in the preparation of polymer micelles. Among them, free radical active polymerization is more practical. The reversible addition-fragmentation chain transfer (RAFT) and atom transfer radical polymerization (ATRP) were highlighted. Additionally, different shapes such as spheres, worms, and vesicles can be obtained by RAFT in the preparation of nano-objects fields. Researchers construct the phase diagram to get the pure phase for applications. As one form produced by PISA, polymeric micelles are usually artificial nanoreactors for a series of organic and inorganic catalysis and can be used as drug delivery and target agents. Due to the increase in the ultimate tensile strength, RAFT is an optimal technique to produce thermoplastic elastomers.

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Feast, W. J. "Anthony Ledwith CBE. 14 August 1933—5 January 2015." Biographical Memoirs of Fellows of the Royal Society 64 (March 14, 2018): 285–98. http://dx.doi.org/10.1098/rsbm.2017.0029.

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Tony Ledwith's early work at University of Liverpool is best known for the identification, characterization and use of free carbocations; in particular, demonstrating their advantages in allowing very high rates of vinyl addition and ring opening polymerizations. During a long career in academia and industry, his research predominantly focused on cationic and cation-radical mechanisms, but ranged across many aspects of polymerization mechanisms, properties and the applications of polymeric materials. His interests were always very wide, for example in surface characterization and modification. In his industrial career, his company was one of the very early adopters of scanning probe microscopies. He was an energetic enthusiast and became heavily involved in science politics, to the considerable benefit of the UK community, particularly chemists and polymer chemists.

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Penczek, Stanisław, and Graeme Moad. "Glossary of terms related to kinetics, thermodynamics, and mechanisms of polymerization (IUPAC Recommendations 2008)." Pure and Applied Chemistry 80, no. 10 (January 1, 2008): 2163–93. http://dx.doi.org/10.1351/pac200880102163.

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This document presents recommended definitions of basic terms related to polymerization processes. Recent developments relating to the kinetics, thermodynamics, and mechanisms of polymerization have necessitated the introduction of new terms and some revision or augmentation of terms previously defined in the Compendium of Chemical Terminology (the "Gold Book") or the IUPAC "Glossary of Basic Terms in Polymer Science".

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