Anionic polymerization of (meth)acrylic monomers. 4. Effect of lithium salts as ligands on the "living" polymerization of methyl methacrylate using monofunctional initiators

Varshney, Sunil K.; Hautekeer, J. P.; Fayt, Roger; Jérôme, Robert; Teyssié, Philippe

doi:10.1021/ma00212a004

Cited by 244 publications

(193 citation statements)

References 4 publications

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“…25 Other Polymerization Systems Anionic polymerization of MMA in THF is a versatile method for synthesis of PMMA with controlled molecular weight. BnTMSNLi was used as an initiator for MMA polymerization in THF in the presence or absence of lithium chloride (LiCl), which is known as an effective additive in methacrylate polymerization at À78 C in THF 34 (Table II) proving synthetic utility of BnTMSNLi, though the tacticity control is poor.…”

Section: Identification Of N-benzylmethacrylamidementioning

confidence: 99%

Anionic Polymerization of (Meth)acrylates with Trialkylsilyl-protected Lithium N-Benzylamide

Kitaura

Kitayama

2007

Polym J

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The polymerization of methacrylates with lithium N-benzyltrimethylsilylamide (BnTMSNLi) in the presence of aluminum compounds afforded syndiotactic or heterotactic polymethacrylates with narrow MWD quantitatively. The end-group analysis of these polymers revealed that benzylamino end-group was quantitatively introduced at the initiating chain-ends of the polymers. The initiator efficiency of the polymerization was slightly lower than unity (0.8-0.9), suggesting possible side reactions in the initiation process. The crude reaction mixture from methyl methacrylate (MMA) polymerization with BnTMSNLi was found to contain a small amount of N-benzylmethacrylamide, which should be formed through the 1,2-addition (carbonyl addition) of BnTMSNLi to MMA in the initiation step of the polymerization. The in situ formed silylsubstituted methacrylamide was not involved in the further polymerization process, as MALDI-TOF mass analysis of the formed polymer indicated the absence of the respective unit in the polymer chain. The methacrylamide remained intact was transformed to N-benzylmethacrylamide when the polymerization was terminated with acidified methanol. Therefore, 1,4-/ 1,2-addition selectivity in the initiation step could be estimated by NMR spectroscopic quantification of the benzylamino end-group in the polymer and N-benzylmethacrylamide in the polymerization mixture. A lithium amide with bulky triisopropylsilyl substituent, BnTIPSNLi, completely suppressed the 1,2-addition and thus the methacrylamide formation, while 15% of BnTMSNLi and 2% of BnTBSNLi, tert-butyldimethylsilyl derivative, underwent the 1,2-addition.KEY WORDS: MMA / Anionic Polymerization / End-functional Polymer / Lithium Amide / 1,2-Addition / 1,4-Addition / Methacrylamide / End-functional polymers have attracted much attention since they can be used for constructing more elaborated polymer chain architectures. 1 Living polymerization, the concept of which was first proposed by Szwarc, 2 is one of the most promising ways to introduce a specified functional group at a polymer chain-end through the reaction of the living polymers with the respective functional reagent. 3 Another means to obtain end-functional polymers is to polymerize a monomer with an initiator which comprises a functional group or its precursor group. 4 Lithium dialkylamides (R 2 NLi) such as lithium diisopropylamide (LDA) have been known as useful anionic initiators for methacrylate polymerizations. 5-9 For example, Antoun et al. reported that LDA/lithium chloride (LiCl) was an effective initiating system for anionic polymerization of methyl methacrylate (MMA) in tetrahydrofuran (THF) and generated PMMA with narrow molecular weight distribution (MWD) in high initiator efficiency (> 0:9). 6,7 The obtained polymer has the tertiary amino group at the chain end, which is less feasible for further chemical modification than primary and secondary amino groups. Kubo et al. reported that polymerization of MMA with N, N 0 -diphenylethylenediamine monolithium amide in THF afforded PMMA havin...

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Section: Identification Of N-benzylmethacrylamidementioning

confidence: 99%

Anionic Polymerization of (Meth)acrylates with Trialkylsilyl-protected Lithium N-Benzylamide

Kitaura

Kitayama

2007

Polym J

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“…24 Freshly distilled THF and lithium chloride (10% weight based on initiator, dried overnight at 130¡C) were introduced under a nitrogen atmosphere to a dry Schlenk tube Ðtted with a magnetic stirrer. Sufficient red solution of a-methylstyryl-lithium was then added dropwise until the reaction mixture turned from colourless to yellow.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and characterization of poly(methylphenylsilylene)- poly(methyl methacrylate) block copolymers

Lutsen

Jones

1998

Polym. Int.

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“…As a result, concentrations of Al and Li are substantially high. These metals are assumed to be derived from polymer synthesis [5]. Figure 4a for HDPE 2 nm membrane filtration, Al and Li are removed at a certain efficiency, but with no contact time dependence, indicating that the removal is not by adsorption.…”

Section: Gel Removal In Ion Exchange Filtermentioning

confidence: 99%

Mechanism investigation of filtration on metal and gel removal from DSAL resist

Umeda¹,

Tsuzuki²,

Takakura³

et al. 2015

J. Photopol. Sci. Technol.

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Reduction of impurities such as gels and metals is one of the critical requirements in chemistries used in directed self assembly lithography (DSAL). In this study, we focused on elucidating the forms of the gels and metals in block copolymer (BCP) solution to effectively reduce these impurities. As a result, particles or gels, and ions are suggested as forms of metals. To reduce these multiple forms of metals, multistep filtrations such as repetitive filtration of single filter material and combination of different type of filters are conducted. As a result, more than 99.99% of Li and more than 99.9% of Al are reduced with a combination of Nylon 6,6 10 nm filtration and ion exchange filtration. The order of the filtration steps does not impact the removal efficiency. The results should contribute realizing DSAL in semiconductor device fabrication.

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Anionic polymerization of (meth)acrylic monomers. 4. Effect of lithium salts as ligands on the "living" polymerization of methyl methacrylate using monofunctional initiators

Cited by 244 publications

References 4 publications

Anionic Polymerization of (Meth)acrylates with Trialkylsilyl-protected Lithium N-Benzylamide

Anionic Polymerization of (Meth)acrylates with Trialkylsilyl-protected Lithium N-Benzylamide

Synthesis and characterization of poly(methylphenylsilylene)- poly(methyl methacrylate) block copolymers

Mechanism investigation of filtration on metal and gel removal from DSAL resist

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