Radical polymerization of methyl methacrylate in the presence of magnesium bromide as the Lewis acid

Nakamura, Shoji

doi:10.1002/(sici)1097-4628(19991010)74:2<290::aid-app9>3.3.co;2-x

Cited by 11 publications

(13 citation statements)

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“…Past studies have explored the polymerization of methyl methacrylate (MMA), acrylonitrile, and VIm with the addition of Lewis acids with different metal cations. 27,28,29 These experimental studies have suggested that certain metals are likely to form a ligand complex with monomers and smaller polymer chains in solution, and these specific interactions can enhance the coordination of specific molecules, leading to increased polymerization rates. Lithium bistriflimide (LiTf 2 N) is a bulky salt that exhibits significant solubility in organic solvents, and it has been shown to facilitate the polymerization of MMA 30 at relatively low concentrations as well as 1vinylimidazole at higher monomer:salt ratios.…”

Section: Introductionmentioning

confidence: 99%

Enhancing the pre-polymerization coordination of 1-vinylimidazole

Hamilton

Abedini

Zhang

et al. 2015

Chemical Engineering Science

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Recent experimental investigations have found that the rate and conversion of the photopolymerization of 1-vinylimidazole (VIm) can be significantly accelerated with the addition of lithium bistriflimide (LiTf 2 N). However, the underlying molecular-level interactions responsible for this phenomenon are unclear. The two components, VIm and LiTf 2 N, are miscible over a wide range of concentrations and form liquid phases at ambient temperature, and if the fundamental behavior of this mixture can be clearly quantified, there are significant opportunities for tuning the polymerization dynamics, polymer structure, and properties. In this work, molecular dynamics (MD) simulations are used to model the underlying pre-polymerization structure of VIm + LiTf 2 N mixtures at several different concentrations. It is found that the Li + enhances the site-site interactions of key functional groups involved in the polymerization, and this is suggested to play a major role in the experimentally-observed enhancement of the polymerization behavior.

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Section: Introductionmentioning

confidence: 99%

Enhancing the pre-polymerization coordination of 1-vinylimidazole

Hamilton

Abedini

Zhang

et al. 2015

Chemical Engineering Science

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“…This mechanism is also analogous to that cited in the extensive literature on Lewis acidmediated radical polymerization. 2,[43][44][45][46][47][48][49][50][51][52] However, even if it can be assumed that the COO − groups are chelated in a pairwise manner, there is still a second propagation pathway available where Ca 2+ coordinates between the terminal and incoming monomer side chains instead. This alternative coordination mode would not regulate the relative orientation of the terminal and penultimate COO − groups.…”

Section: Catalysis Versus Stereocontrolmentioning

confidence: 99%

Isotactic Regulation in the Radical Polymerization of Calcium Methacrylate: Is Multiple Chelation the Key to Stereocontrol?

Noble

Coote

2019

Journal of Polymer Science

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Accurate quantum chemistry is used to explain the origins of isospecificity in radical polymerization of calcium methacrylate hydrate (CaMA). Distonic radical–cation interactions are shown to be crucial in determining the reactivity of different coordination structures. Cation coordination to the terminal and incoming monomer side chains reduces radical‐cation separation, enhancing the reactivity of these modes over the stereocontrolling terminal‐penultimate binding modes. This explains why Lewis acid‐mediated radical polymerization often fails to produce highly isotactic polymer for common monomers such as methyl methacrylate. However, theoretical calculations suggest that the poly(CaMA) terminus forms a chelated bridging scaffold in N,N‐dimethylformamide (DMF), which involves the terminal, penultimate and incoming monomer carboxylate groups. This scaffold simultaneously activates the incoming monomer toward propagation and regulates the relative orientation of the terminal and penultimate side chains. The bridging scaffold is disrupted in more polar solvents and/or if alternative nonchelating counter‐cations are employed, leading to loss of isotactic control. These results suggest that higher levels of isotactic control may be achievable if reaction conditions are optimized to favor bridging scaffold formation. The broader importance of these findings to stereocontrol in radical polymerization is also discussed. © 2019 Wiley Periodicals, Inc. J. Polym. Sci. 2020, 58, 52–61

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“…11 The Lewis acids, such as scandium trifluoromethanesulfonate [scandium triflate, Sc(OTf) 3 ],12 Yb(OTf) 3 , and hafnium chloride (HfCl 4 ), reduced the syndiotacticity during the radical polymerization [initiator: azobisisobutyronitrile (AIBN)], in comparison with that of the polymer prepared in the absence of Lewis acids. The effect of magnesium bromide as a Lewis acid in the radical polymerization of MMA has been already investigated 13…”

Section: Methacrylatesmentioning

confidence: 99%

Stereocontrol in radical polymerization

Habaue¹

2001

Chem. Record

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The stereospecific radical polymerization of vinyl esters, methacrylates, and alpha-substituted acrylates was studied. Fluoroalcohols, as a solvent, have remarkable effects on the stereoregularity of the radical polymerizations of vinyl acetate, vinyl pivalate, and vinyl benzoate, affording polymers rich in syndiotacticity, heterotacticity, and isotacticity, respectively. This method was successfully applied to the polymerization of methacrylates to give syndiotactic polymers. The steric repulsion between the entering monomer and the chain-end monomeric unit bound by the solvent through hydrogen bonding is important for the stereochemical control in these systems. Lewis acid catalysts, such as lanthanide trifluoromethanesulfonates and zinc salts, were also effective for the stereocontrol during the radical polymerization of methyl methacrylate, to reduce the syndiotacticity and alpha-(alkoxymethyl)acrylates to synthesize isotactic and syndiotactic polymers. Radical polymerization of the methacrylates bearing a bulky ester group, such as the triphenylmethyl methacrylate derivatives, gave highly isotactic polymers, as in the case of anionic polymerization. In addition, the control of one-handed helical conformation was attained in the radical polymerization of 1-phenyldibenzosuberyl methacrylate using chiral neomenthanethiol or cobalt(II) complexes as an additive.

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Radical polymerization of methyl methacrylate in the presence of magnesium bromide as the Lewis acid

Cited by 11 publications

References 0 publications

Enhancing the pre-polymerization coordination of 1-vinylimidazole

Enhancing the pre-polymerization coordination of 1-vinylimidazole

Isotactic Regulation in the Radical Polymerization of Calcium Methacrylate: Is Multiple Chelation the Key to Stereocontrol?

Stereocontrol in radical polymerization

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