- Main-Chain and Side-Chain Sequence-Regulated Vinyl Copolymers by Iterative Atom Transfer Radical Additions and 1:1 or 2:1 Alternating Radical Copolymerization
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Main- and side-chain sequence-regulated vinyl copolymers were prepared by a combination of iterative atom transfer radical additions (ATRAs) of vinyl monomers for side-chain control and 1:1 or 2:1 alternating radical copolymerization of the obtained side-chain sequenced "oligomonomers" and vinyl comonomers for main-chain control. A complete set of sequence-regulated trimeric vinyl oligomers of styrene (S) and/or methyl acrylate (A) were first synthesized via iterative ATRAs of these monomers to a halide of monomeric S or A unit (X-S or X-A) under optimized conditions with appropriate ruthenium or copper catalysts, which were selected depending on the monomers and halides. The obtained halogen-capped oligomers were then converted into a series of maleimide (M)-ended oligomonomers with different monomer compositions and sequences (M-SSS, M-ASS, M-SAS, M-AAS, M-SSA, M-ASA, M-SAA, M-AAA) by a substitution reaction of the halide with furan-protected maleimide anion followed by deprotection of the furan units. These maleimide-ended oligomonomers were then radically copolymerized with styrene or limonene to enable the 1:1 or 2:1 monomer-sequence regulation in the main chain and finally result in the main- and side-chain sequence-regulated vinyl copolymers with high molecular weights in high yield. The properties of the sequence-regulated vinyl copolymers depended on not only the monomer compositions but also the monomer sequences. The solubility was highly affected by the outer monomer units in the side chains whereas the glass transition temperatures were primarily affected by the two successive monomer sequences.
- Soejima, Takamasa,Satoh, Kotaro,Kamigaito, Masami
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supporting information
p. 944 - 954
(2016/02/05)
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- Electron Spin Resonance Study of Monomeric, Dimeric, and Polymeric Acrylate Radicals Prepared Using the Atom Transfer Radical Polymerization Technique - Direct Detection of Penultimate-Unit Effects
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Model radicals generated through the reaction of organotin compounds with radical precursors prepared by atom transfer radical addition (ATRA) or atom transfer radical polymerization (ATRP) were studied by electron spin resonance (ESR). Dimers of various (meth)acrylate units, methyl acrylate (MA), tert-butyl acrylate (tBA), and methyl methacrylate (MMA), MA-MA-Br, MA-tBA-Br, tBA-tBA-Br, MMA-tBA-Br, and MA-MMA-Br, were prepared by ATRA. These dimers provided radicals mimicking the active species in a radical copolymerization of MA, MMA, and tBA. Well-resolved ESR spectra of the dimeric radicals confirm electronic and steric effects of the penultimate unit on the propagating radical. Hyperfine splitting constants observed for monomeric, dimeric, oligomeric, and polymeric tert-butyl acrylate radicals depend on the polymer chain length. The variation of ESR spectra with the chain length and penultimate unit was compared with the rate constants of activation in an ATRP using a CuBr/bpy catalyst system.
- Kajiwara, Atsushi,Nanda, Ajaya Kumar,Matyjaszewski, Krzysztof
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p. 1378 - 1385
(2007/10/03)
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