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Ionic Polymerizations
Published in Richard A. Pethrick, Gennadi E. Zaikov, Teiji Tsuruta, Naoyuki Koide, Polymer Yearbook 13, 2019
Alkyl halides bearing an epoxy group (20) (183, E44) and a 1,3-butadiene unit (21) (1836, El124) were used as end-capping agents for anionic living polymers to prepare end-functionalized polymers. Despite the existence of the anionically polymerizable functions, these quenchers cleanly terminated living polymers of styrene and isoprene (countercation: Li+) to achieve nearly quantitative attachment of the ω-end polymerizable functional groups. Functionalized monomers for anionic polymerization.References: 9 (181, E43); 10 (184, E44; 1832, E1123); 11 (1832, E1123); 12 (178, E41); 13 (1828, E1122); 14 (180, E42); 15 (185, E45; 1880, E1135); 16 (176, E40); 17 (1830, E1123); 18 (179, E42); 19 (1826, E1122).End-capping agents for anionic living polymers.References: 20 (183, E44); 21 (1836, E1124); 22 and 23 (1838, E1125); 24 (1834, E1124).
Monomers, Polymers, and Plastics
Published in James G. Speight, Handbook of Petrochemical Processes, 2019
An example of anionic chain growth polymerization is the treatment of a cold tetrahydrofuran solution of styrene with 0.001 equivalents of n-butyl lithium causes an immediate polymerization. Chain growth may be terminated by water or carbon dioxide, and chain transfer seldom occurs. Only monomers having anion stabilizing substituents, such as phenyl, cyano, or carbonyl are good substrates for this polymerization technique. Many of the resulting polymers are largely isotactic in configuration, and have high degrees of crystallinity. Species that have been used to initiate anionic polymerization include alkali metals, alkali amides, and alkyl lithium compounds.
Chain-Growth Polymerization
Published in Anil Kumar, Rakesh K. Gupta, Fundamentals of Polymer Engineering, 2018
Anionic polymerization is initiated by compounds that release anions in the reaction mass. Cationic and anionic polymerization are very similar in nature, except in their termination reactions. Termination reactions can occur easily in cationic polymerization, whereas they are almost absent in anionic polymerization. In both cases, there is a gegen ion adjacent to the growing center. Therefore, their initiation and propagation rates have similar characteristics.
Quantifying separation energy with a modified Capillary Break-up Extensional Rheometer (CaBER) to study polymer solutions
Published in Soft Materials, 2021
Kamran Riazi, Mahdi Abbasi, Christopher O. Klein, Ingo F. C. Naue, Manfred Wilhelm
A sample of linear poly(methyl methacrylate) (PMMA) was synthesized via anionic polymerization. The initiator for the polymerization of methyl methacrylate (MMA), sec-Butyllithium (sec-BuLi), was prepared in dry toluene. The desired amount of the sec-BuLi was added into the toluene (~20 ml) under argon counter flow. Then an excess of 1,1-diphenylethylene (10% excess) was added to the toluene/sec-BuLi solution and the mixture was stirred for 30 min at room temperature. The polymerization of MMA was carried out in tetrahydrofuran (THF) (v/v (THF/MMA) = 15/1), which was cooled to approximately −80°C using an acetone/liquid nitrogen cooling bath. The initiator was added quickly to the THF/MMA solution and stirred for 1 h. The living polymer was terminated by adding a small amount of degassed MeOH, and then was precipitated in MeOH and dried at 70°C under vacuum.
Integration of CFD and polymerization for an industrial scale cis-polybutadiene reactor
Published in Chemical Engineering Communications, 2018
Chaozhong Xu, Jiajun Wang, Xueping Gu, Lianfang Feng
To summarize, these studies mostly focused on flow (Patel et al., 2010; Fathi Roudsari et al., 2013), mixing (Tosun and Bakker, 1997; Kolhapure and Fox, 1999; Wells and Ray, 2005), and heat transfer (Cherbański et al., 2007) inside the lab-scale polymerization reactor. Several researchers (Zhou et al., 2001; Serra et al., 2007; Zhu et al., 2014; Xie and Luo, 2017; Xie et al., 2016, 2017; Xu et al., 2017) have used CFD to relate the mixing quality to the polymer quality indices, such as number-average molecular weight (Mn), mass-average molecular weight (Mw), and PDI. Little attention has been paid to investigate the final polymer properties by CFD modeling for an industrial anionic polymerization process. In this work, the CFD approach coupling with anionic polymerization kinetics is used to investigate the hydrodynamics and polymerization process in an industrial cis-polybutadiene reactor. And the effects of key operating variables are also discussed.
Preparation techniques of thin cyanoacrylate adhesive films for interface analysis
Published in The Journal of Adhesion, 2022
Philipp Moritz, Friedrich Bürger, Lienhard Wegewitz, Wolfgang Maus-Friedrichs
The rest -R represents methyl, ethyl and longer-chain alkyl groups. These influence the curing time and the physical and mechanical properties of the polymer.[7] The curing mechanism has already been studied in numerous publications and identified as an anionic polymerization. The initiating anion is usually a hydroxide ion that originates from the surrounding humidity or water molecules adsorbed on the surface of the materials to be joined.[8,9]