“…Also, transesterification reactions between PEO anions and MMA monomers increase the product heterogeneity due to the formation of grafted block copolymers as already found by Suzuki for the corresponding triblocks. [24,25] The difficulties discussed above for the polymerization of MMA initiated with living PEO [23] can be avoided by replacing MMA by TBMA as this monomer is less sensitive to transesterification side reactions and can be polymerized without transfer and termination reactions even at room temperature. Furthermore, the hydrophobic PTBMA block can be hydrolyzed with acid to quantitatively yield a MAA block.…”
Section: Hydrophobic Precursor Blocksmentioning
confidence: 99%
“…[24,25,65] Such initiator systems were also used for the polymerization of acrylonitrile (AN) [66 -68] and methyl acrylonitrile. [68] These polymerizations often did not lead to well-defined polymers due to side reactions.…”
“…Also, transesterification reactions between PEO anions and MMA monomers increase the product heterogeneity due to the formation of grafted block copolymers as already found by Suzuki for the corresponding triblocks. [24,25] The difficulties discussed above for the polymerization of MMA initiated with living PEO [23] can be avoided by replacing MMA by TBMA as this monomer is less sensitive to transesterification side reactions and can be polymerized without transfer and termination reactions even at room temperature. Furthermore, the hydrophobic PTBMA block can be hydrolyzed with acid to quantitatively yield a MAA block.…”
Section: Hydrophobic Precursor Blocksmentioning
confidence: 99%
“…[24,25,65] Such initiator systems were also used for the polymerization of acrylonitrile (AN) [66 -68] and methyl acrylonitrile. [68] These polymerizations often did not lead to well-defined polymers due to side reactions.…”
“…In a previous paper, we suggested the possibility of a transesterification reaction between the disodium salt of PEO and the methoxy group of the PMMA portion in the copolymer or MMA monomer from 1 H NMR analyses. 16 Since unreacted PEO could be contained in the copolymer recovering process, the peaks due to PEO should have appeared in GPC traces, occasional unreacted PEO in the reaction system. Figure I shows the GPC traces of the copolymers prepared i.n the presence of the crown ether at different M/1 ratios.…”
Section: Transesterific:ation Reactionmentioning
confidence: 99%
“…As reported in a previous paper, in the absence of the crown ether, the triad stereosequence distributions deviated from Bernoullian statistics. 16 However, the polymers shown in No. 7 are well-defined by Bernoullian statistics.…”
Section: Stereosequence Distributions Of Pmma Part In the Copolymersmentioning
Anionic polymerization of methyl methacrylate (MMA) was initiated with the disodium salt of poly(ethylene oxide) (PEO) in tetrahydrofuran (THF) in both the presence and absence of a crown ether or cryptate. The resulting block copolymer of poly(methyl methacrylate) (PMMA) and PEO was characterized by 1 Hand 13 C-NMR spectroscopies, gel-permeation chromatography and solvent extractions. The transesterification reaction between PEO and methoxy group in MMA was accompanied by polymerization, resulting in a PEO grafted triblock copolymer. A benzylamino derivative of PEO (PEO-N) was prepared as a new initiator system for the polymerization of MMA. The initiation with disodium or dilithium amide of PEO-N resulted in a linear triblock copolymer of PMMA-PEO-PMMA having a unimodal and narrower molecular weight distribution. The stereosequence distributions of the PMMA part in the copolymers were essentially atactic and the addition of the crown ether or the cryptate increased the fraction of the rr triad. KEY WORDS Anionic Polymerization Methyl Methacrylate Poly(ethylene oxide) I Alkali Metal Alkoxide I Alkali Metal Amide I Crown Ether I Cryptate I Triblock Copolymer I Nuclear Magnetic Resonance I
“…However, the solubility of PEO in the commonly used organic solvent of THF is rather low, which might require the higher temperature of at least 20°C for its polymerization to keep the reaction medium homogeneous. 18,19 Obviously, neither high nor low temperature can be suitable for the ideal anionic polymerization conditions of EO and MMA simultaneously. Table I shows the data of block copolymerization of EO and MMA using our initiation system.…”
Section: Block Copolymerization Of Eo and Mmamentioning
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