Polymerization of methyl methacrylate by latent pre-catalysts based on CO2-protected N-heterocyclic carbenes

Naumann, Stefan; Schmidt, Friedrich Georg; Schowner, Roman; Frey, Wolfgang; Buchmeiser, Michael R.

doi:10.1039/c3py00073g

Cited by 52 publications

(87 citation statements)

References 52 publications

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“…[ 10,16,19,20 ] For the synthesis of poly(ε-caprolactam) and poly(ε-caprolactam)-co -poly(lauryllactam) by the action of protected NHCs and their properties, refer to refs. [9 , 13] To obtain melt spun poly-LL-co -poly-ε-CL fi bers, 3 g (75 wt%) of CL, 1 g (25 wt%) of LL, and 5 wt% of 6-Cy-CO 2 were mixed in a mortar inside a glove box.…”

Section: Methodsmentioning

confidence: 99%

“…They are semicrystalline, thermoplastic polymers with good heat-and chemical stability and excellent mechanical performance. PAs can be prepared by polycondensation from dicarboNHCs to establish themselves as initiators/catalysts for various polymerizations, including the polymerization of methyl methacrylate, [ 10,11 ] ethylene oxide, propylene oxide [ 12 ] as well as of lactams [ 13 ] and lactides. [ 14 ] Most of the NHCs are based on imidazol-2-ylidenes or imidazolin-2-ylidenes; however, increasing interest is devoted to the much more basic tetrahydropyrimidin-2-ylidenes.…”

Section: Introductionmentioning

confidence: 99%

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In Situ Copolymerization of Lactams for Melt Spinning

Jovic

Unold

Naumann

et al. 2016

Macromol. Mater. Eng.

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The copolymerization of lauryl lactam (LL) with ε‐caprolactam (ε‐CL) initiated by the latent, CO2‐protected N‐heterocyclic carbene‐based initiators 1,3‐dicyclohexyl‐3,4,5,6‐tetrahydropyrimidinium carboxylate (6‐Cy‐CO2), and 1,3‐dimethyl‐3,4,5,6‐tetrahydropyrimidinium carboxylate (6‐Me‐CO2) has been explored. The temperature‐dependent exchange of the protecting group in 6‐Cy‐CO2 and 6‐Me‐CO2 with 13C‐labeled CO2 is studied to gain knowledge about the onset of CO2 release from the carbene. Under exclusion of moisture, a storable batch containing 75 wt% ε‐CL, 25 wt% LL, and another 5 wt% 6‐Cy‐CO2 can be prepared. This batch is successfully used in the in situ melt spinning of poly(ε‐CL)‐co‐poly(LL)‐based single‐filament fibers.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

In Situ Copolymerization of Lactams for Melt Spinning

Jovic

Unold

Naumann

et al. 2016

Macromol. Mater. Eng.

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“…Because of their nucleophilicity they show high reactivity towards various substrates but they can also be masked in thermally labile precursors [67]. NHCÀmetal complexes have been applied as thermally latent catalysts in the preparation of a number of polymers, such as poly(urethane), poly(methyl methacrylate), poly(caprolactone) and poly (amide) [68][69][70][71][72].…”

Section: Mechanochemical Catalysismentioning

confidence: 99%

Mechanochemical Reactions Reporting and Repairing Bond Scission in Polymers

Clough

Balan

Sijbesma

2015

Topics in Current Chemistry

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The past 10 years have seen a resurgence of interest in the field of polymer mechanochemistry. Whilst the destructive effects of mechanical force on polymer chains have been known for decades, it was only recently that researchers tapped into these forces to realize more useful chemical transformations. The current review discusses the strategic incorporation of weak covalent bonds in polymers to create materials with stress-sensing and damage-repairing properties. Firstly, the development of mechanochromism and mechanoluminescence as stress reporters is considered. The second half focuses on the net formation of covalent bonds as a response to mechanical force, via mechanocatalysis and mechanically unmasked chemical reactivity, and concludes with perspectives for the field.

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“…The widespread utility of these durable high-strength materials is manifested from the various applications in the form of fibers, industrial yarns, floor covering and engineering plastics or films. [21][22][23][24][25][26][27][28][29] In addition to intense energy requirements, these high-temperature reactions have several other drawbacks, including the formation of undesired side products. [2] With the increase in environmental regulation toward reduction of industrial energy consumption and carbon dioxide (CO 2 ) emission, significant efforts are being made to develop a greener and more efficient technology for making nylon.…”

mentioning

confidence: 99%

Polymerization of ϵ‐Caprolactam to Nylon‐6 Catalyzed by Barium σ‐Borane Complex under Mild Condition

Bhattacharjee

Harinath

Sarkar³

et al. 2019

ChemCatChem

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A mild and low-temperature synthesis of nylon-6 is achieved through the ring-opening polymerization of ɛ-caprolactam using barium σ-borane complex as the catalyst. Due to the mild nature of the catalyst, this protocol provides an easy means of synthesizing nylon-6, for the first time with a precise and predictable molecular weight. From various model experiments, it is evident that the σ-coordinated boron hydride acts as a mild hydride donor in the first step of the reaction to generate lactamate anions, which then undergo ring-opening polymerization in-situ with the remaining caprolactam molecules under the influence of the dehydrogenated boron metal complex.Polyamides are among the most versatile synthetic polymers and are indispensable to modern life. The widespread utility of these durable high-strength materials is manifested from the various applications in the form of fibers, industrial yarns, floor covering and engineering plastics or films. [1] Among all the polyamides available today, poly (ɛ-caprolactam) or nylon-6 alone represents approximately 45 % of worldwide production in terms of volume. [2] With the increase in environmental regulation toward reduction of industrial energy consumption and carbon dioxide (CO 2 ) emission, significant efforts are being made to develop a greener and more efficient technology for making nylon. [3][4][5][6][7][8][9][10] The industrial production of nylon-6 is commonly carried out by means of anionic polymerization, which is performed hydrolytically at 250°C or at a relatively lower temperature of 150°C in the presence of an initiator. [11][12][13][14][15][16][17][18][19][20] Buchmeiser et al. reported a series of N-heterocyclic carbenes (NHCs) as initiators at temperatures of 180-200°C for anionic ring-opening homo as well as copolymerization of lactams to give corresponding polyamide PA 12 and PA 6/12. [21][22][23][24][25][26][27][28][29] In addition to intense energy requirements, these high-temperature reactions have several other drawbacks, including the formation of undesired side products. The properties of nylon-6 synthesized through anionic polymerization are often shaped by irregularities in the polymer chain because of side reactions such as Claisen-type condensations that occur during the polymerization of ɛ-caprolactam. These side reactions are strongly marked by weak heat exchange with the surrounding medium during typical bulk polymerization. [30] Ricco et al. have studied the influence of fast activators on the chain regularity and polymorphism of synthesized nylon-6. [31] At the same time, cationic initiation is not as useful as its anionic counterparts because of poor conversion and low molecular weight of the resultant polymer.Furthermore, while the use of an alkali or alkaline metal or alkali metal hydride enables the synthesis of nylon-6 in good proportion, the side reactions adulterate the product with amines and water, which destroy reactive initiator and propagate a species that often promotes polymer branching and chain irregularities. Therefo...

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Polymerization of methyl methacrylate by latent pre-catalysts based on CO2-protected N-heterocyclic carbenes

Cited by 52 publications

References 52 publications

In Situ Copolymerization of Lactams for Melt Spinning

In Situ Copolymerization of Lactams for Melt Spinning

Mechanochemical Reactions Reporting and Repairing Bond Scission in Polymers

Polymerization of ϵ‐Caprolactam to Nylon‐6 Catalyzed by Barium σ‐Borane Complex under Mild Condition

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