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New cobalt-mediated radical polymerization (CMRP) of methyl methacrylate initiated by two single-component dinuclear β-diketone cobalt (II) catalysts.

Bao F, Feng L, Gao J, Tan Z, Xing B, Ma R, Yan C - PLoS ONE (2010)

Bottom Line: Two dinuclear cobalt complexes based on bis-diketonate ligands (ligand 1: 3,3'-(1,3-phenylene)bis(1-phenylpropane-1,3-dione); ligand 2: 3,3'-(1,4-phenylene)bis(1-phenylpropane-1,3-dione)) were successfully synthesized.The resulting polymerizations have all of the characteristics of a living polymerization and displayed linear semilogarithmic kinetic plots, a linear correlation between the number-average molecular weight and the monomer conversion, and low polydispersities.All these improvements facilitate the implementation of the acrylate CMRP and open the door to the scale-up of the syntheses and applications of the multicomponent low polydispersity polymers.

View Article: PubMed Central - PubMed

Affiliation: College of Chemistry, Central China Normal University, Wuhan, China. polymerbaofeng@yahoo.com.cn

ABSTRACT
Two dinuclear cobalt complexes based on bis-diketonate ligands (ligand 1: 3,3'-(1,3-phenylene)bis(1-phenylpropane-1,3-dione); ligand 2: 3,3'-(1,4-phenylene)bis(1-phenylpropane-1,3-dione)) were successfully synthesized. The two neutral catalysts all showed satisfactory activities in the cobalt-mediated radical polymerization (CMRP) of methyl methacrylate (MMA) with the common initiator of azodiisobutyronitrile (AIBN). The resulting polymerizations have all of the characteristics of a living polymerization and displayed linear semilogarithmic kinetic plots, a linear correlation between the number-average molecular weight and the monomer conversion, and low polydispersities. Mono- or dicomponent low polydispersity polymers could be obtained by using the two dinuclear catalysts under proper reaction conditions. All these improvements facilitate the implementation of the acrylate CMRP and open the door to the scale-up of the syntheses and applications of the multicomponent low polydispersity polymers.

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Size-exclusion chromatograms for Sample 4–7.
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pone-0013629-g004: Size-exclusion chromatograms for Sample 4–7.

Mentions: Other bulk CMRP results are summarized in Table 1 and the other GPC curves are shown in Figure 3 and Figure 4. The results of two peaks in an individual GPC curves are found in most bulk CMRPs. Nonetheless, there still some polymers had only single narrow molecular weight distribution peak in GPC curve. It could be observed in Figure 3 (Sample 3) and Table 1 (Sample 8, 9, 10). From the above-mentioned GPC results, some unimodal distribution means only one active species worked in the CMRP with the catalyzation of a dinuclear cobalt complex under certain reaction conditions. Take all the GPC results shown in Table 1 into account, we could find the monocomponent polymer obtained by CMRP are all catalyzed by complex 4 (shown in Scheme S2) system. Similar results were not found in complex 5 systems. When will we get monocomponent narrow distribution polymers as well as when will we get two-component narrow distribution polymers, that are very significant questions to us. It is natural for us to explain these questions from the molecular structures of the two dinuclear complexes (complex 4 and complex 5). From Scheme S2, in complex 4, one benzoylacetone substituent group is in the para position to the other benzoylacetone substituent. Relatively, in complex 5, the benzoylacetone substituent group is in the ortho position to the other benzoylacetone substituent. These facts mean the two cobalt metal center in complex 5 is closer than in complex 4. Therefore, for the higher electrophilic and steric effect, the complex 5 is more liable to generate two active species in CMRP. With a comparison to the bi-component polymers catalyzed by complex 4, the mono-component polymers catalyzed by the same complex are all high molecular weight constituent.


New cobalt-mediated radical polymerization (CMRP) of methyl methacrylate initiated by two single-component dinuclear β-diketone cobalt (II) catalysts.

Bao F, Feng L, Gao J, Tan Z, Xing B, Ma R, Yan C - PLoS ONE (2010)

Size-exclusion chromatograms for Sample 4–7.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2964317&req=5

pone-0013629-g004: Size-exclusion chromatograms for Sample 4–7.
Mentions: Other bulk CMRP results are summarized in Table 1 and the other GPC curves are shown in Figure 3 and Figure 4. The results of two peaks in an individual GPC curves are found in most bulk CMRPs. Nonetheless, there still some polymers had only single narrow molecular weight distribution peak in GPC curve. It could be observed in Figure 3 (Sample 3) and Table 1 (Sample 8, 9, 10). From the above-mentioned GPC results, some unimodal distribution means only one active species worked in the CMRP with the catalyzation of a dinuclear cobalt complex under certain reaction conditions. Take all the GPC results shown in Table 1 into account, we could find the monocomponent polymer obtained by CMRP are all catalyzed by complex 4 (shown in Scheme S2) system. Similar results were not found in complex 5 systems. When will we get monocomponent narrow distribution polymers as well as when will we get two-component narrow distribution polymers, that are very significant questions to us. It is natural for us to explain these questions from the molecular structures of the two dinuclear complexes (complex 4 and complex 5). From Scheme S2, in complex 4, one benzoylacetone substituent group is in the para position to the other benzoylacetone substituent. Relatively, in complex 5, the benzoylacetone substituent group is in the ortho position to the other benzoylacetone substituent. These facts mean the two cobalt metal center in complex 5 is closer than in complex 4. Therefore, for the higher electrophilic and steric effect, the complex 5 is more liable to generate two active species in CMRP. With a comparison to the bi-component polymers catalyzed by complex 4, the mono-component polymers catalyzed by the same complex are all high molecular weight constituent.

Bottom Line: Two dinuclear cobalt complexes based on bis-diketonate ligands (ligand 1: 3,3'-(1,3-phenylene)bis(1-phenylpropane-1,3-dione); ligand 2: 3,3'-(1,4-phenylene)bis(1-phenylpropane-1,3-dione)) were successfully synthesized.The resulting polymerizations have all of the characteristics of a living polymerization and displayed linear semilogarithmic kinetic plots, a linear correlation between the number-average molecular weight and the monomer conversion, and low polydispersities.All these improvements facilitate the implementation of the acrylate CMRP and open the door to the scale-up of the syntheses and applications of the multicomponent low polydispersity polymers.

View Article: PubMed Central - PubMed

Affiliation: College of Chemistry, Central China Normal University, Wuhan, China. polymerbaofeng@yahoo.com.cn

ABSTRACT
Two dinuclear cobalt complexes based on bis-diketonate ligands (ligand 1: 3,3'-(1,3-phenylene)bis(1-phenylpropane-1,3-dione); ligand 2: 3,3'-(1,4-phenylene)bis(1-phenylpropane-1,3-dione)) were successfully synthesized. The two neutral catalysts all showed satisfactory activities in the cobalt-mediated radical polymerization (CMRP) of methyl methacrylate (MMA) with the common initiator of azodiisobutyronitrile (AIBN). The resulting polymerizations have all of the characteristics of a living polymerization and displayed linear semilogarithmic kinetic plots, a linear correlation between the number-average molecular weight and the monomer conversion, and low polydispersities. Mono- or dicomponent low polydispersity polymers could be obtained by using the two dinuclear catalysts under proper reaction conditions. All these improvements facilitate the implementation of the acrylate CMRP and open the door to the scale-up of the syntheses and applications of the multicomponent low polydispersity polymers.

Show MeSH