Presentation on theme: "Living Anionic Polymerization of Benzofulvene: Highly Reactive Fixed Transoid 1,3-Diene Yuki Kosaka, Keita Kitazawa, Sotaro Inomata, and Takashi Ishizone*"— Presentation transcript:
Living Anionic Polymerization of Benzofulvene: Highly Reactive Fixed Transoid 1,3-Diene Yuki Kosaka, Keita Kitazawa, Sotaro Inomata, and Takashi Ishizone* ACS Macro Lett. 2013, 2, 164−167 Advisor : Professor Guey-Sheng Liou Speaker : Yi-Chun Yeh Date : 2014.12.26
Outline Author Anionic polymerization Living anionic polymerization Introduction Synthesis process SEC data Copolymerization Free radical & Anionic polymerization Concluding Remarks 1
Author He was born in Saitama, Japan, in April, 1963. He received his M.S in polymer chemistry from Tokyo Institute of Technology in 1988 under supervision of Professors Seiichi Nakahama and Akira Hirao and started his academic career as Assistant Professor from 1989. After receiving doctorate degree in 1994, he spent a postdoctoral research at The University of Chicago with Professor P. E. Eaton on organic chemistry in 1995. Since 2000 he is Associate Professor of Department of Organic and Polymeric Materials at Tokyo Institute of Technology. His current research interests are centered on synthesis of novel thermally-stable polymers possessing adamantyl groups synthesis of novel water-soluble thermo-responsive polymers by means of living anionic polymerization. Takashi Ishizone 石曽根 隆 2
Anionic polymerization Anionic polymerization is a form of chain-growth polymerization or addition polymerization that involves the polymerization of vinyl monomers with strong electronegative groups. 3 This polymerization is carried out through a carbanion active species. Anionic polymerizations are used in the production of polydiene synthetic rubbers, solution styrene/butadiene rubbers (SBR), and styrenic thermoplastic elastomers.
Anionic polymerization 4 Initiation by Electron Transfer Initiation involve the transfer of an electron from the alkali metal to the monomer to form an anion-radical. Initiation by Strong Anions The initiation process involves the addition of a neutral (B:) or negative (B:-) nucleophile to the monomer. Nucleophilic initiators include metal amides, alkoxides, and organometallic compounds (alkyllithium compounds and Grignard reagents). The reactivity of initiators used in anionic polymerization should be similar to that of the monomer is the propagating species. The least reactive monomers have the largest pKa values for their corresponding conjugate acid and thus, require the most reactive initiator.
Anionic polymerization characteristics that distinct from free radical polymerization : Anionic polymerization 1.High selectivity of monomers 2.Water can’t exist in the reaction system 3.Polymerization rate fast, low activation energy, usually occurs in low temperature 4.Without termination or chain transfer 5 By controlling the effects of counterion, solvent, temperature, Lewis base additives, and inorganic solvents, increase the potential of anionic polymerizations
Living Anionic polymerization Living polymerization of features: rapid initial, slow growth, no termination, no transfer reaction. Monomer had been consumed, the anion remains active. Add new monomers, polymerization can continue; molecular weight increased with conversion in present, narrow molecular weight distribution; the end groups of the polymer, the composition, structure and molecular weight can be controlled. 6
Introduction Fulvene (FV), C 6 H 6 one of isomer of Benzene, show high reactivity toward various derivatives. (strongly polarized!) Possible to anionic polymerization Fixed Transoid 1,3-Diene 7 Nakano, T.; Yade, T.; Fukuda, Y.; Yamaguchi, T.; Okumura, S. Macromolecules 2005, 38, 8140−8148. Only 1,2-addition!
SEC Table 1. Anionic Polymerization of BF in THF at −78 °C for 1 h a a Yield ∼ 100%. b Mn(calcd) = (MW of monomer) × [M]/[I] + MW of initiator. c Mn(obsd) was determined by SEC-RALLS equipped with refractive index (RI), light scattering (LS), and viscometer detectors. d Mw/Mn was determined by SEC calibration using polystyrene standards in THF. e For 15 h. f For 20 h. 9
Copolymerization Scheme 1. Block Copolymerization of BF with Living Poly(MMA) Poly(MMA) Poly(BF) Poly(MMA)-block-poly(BF)Poly(BF)-block-poly(MMA) relative acidity of conjugated acid for indene (pKa = 20.1) is significantly higher than that of ethyl acetate (pKa = 24.4) Anionic polymerizability of BF was remarkably high and comparable to that of MMA. 10
Free radical & Anionic polymerization Poly(BF-a) Poly(BF-r) Polymerization modes of BF and four possible diad units in poly(BF). 11
Concluding Remarks we have succeeded in the living anionic polymerization of a novel exomethylene monomer, BF, to afford polymers with predicted molecular weights and narrow MWDs. The extremely high anionic polymerizability of this hydrocarbon is newly demonstrated and comparable to MMA. BF acts as a conjugated 1,3-diene to give only polymers containing the 1,2- and 1,4-addition modes. 12