Recent advance in syntheses and applications of well-defined end-functionalized polymers by means of anionic living polymerization

Hirao, Akira; Hayashi, Mayumi

doi:10.1002/(sici)1521-4044(19990701)50:7<219::aid-apol219>3.0.co;2-u

Cited by 112 publications

(93 citation statements)

References 54 publications

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“…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.…”

mentioning

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

Kitaura

Kitayama

2007

Polym J

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“…72 the direct introduction of benzyl halide function into living anionic polymers would be most effective, it is not possible since benzyl halide functions are highly reactive and incompatible with living anionic polymers. Instead, we have at first employed the anion-stable methoxymethylphenyl group as a precursor of the benzyl chloride function during the reactions of living anionic polymers and subsequently transformed the methoxymethylphenyl groups introduced into benzyl chlorides.…”

Section: Synthesis Of Chain-end-and In-chain-functionalized Polymers mentioning

confidence: 99%

“…72,95,96,104 The regular stars have also be synthesized by using the same living polymers as polymeric coupling agents in main chain. The reactions were usually fast in THF even at −78 • C and went essentially to completion within 1 h. However, the reactions were in most cases carried out for 24-168 h by way of precaution.…”

Section: Coupling Reaction Of Living Anionic Polymers With Benzyl Halmentioning

confidence: 99%

“…[65][66][67] Some other excellent reviews on the same subject have also recently appeared. 51,[68][69][70][71][72][73][74] Several research groups have widely studied the methodology in which difunctional monomers such as divinylbenzene and ethyleneglycol dimethacrylate are reacted with anionic species present at the initiation or termination stages of living polymerization to synthesize star polymers. [75][76][77][78][79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94] Since well control of such reactions is difficult, the core parts of the resulting star polymers have always some distributions.…”

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Precise Synthesis of Regular and Asymmetric Star Polymers and Densely Branched Polymers with Starlike Structures by Means of Living Anionic Polymerization

Hirao

Hayashi

Tokuda

et al. 2002

Polym J

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ABSTRACT:The subject of this review is to present new synthetic methodologies recently developed by us, which are applicable to both regular and asymmetric star polymers with well-defined architectures. The first methodology involves the coupling reaction of a variety of living anionic polymers of styrene, α-methylstyrene, isoprene, tert-butyl methacrylate, and ethylene oxide with novel chain-end-and in-chain-functionalized polymers with a definite number of benzyl halide moieties intentionally designed as polymeric coupling agents. In the second methodology, we propose a new concept based on iterative approach, with which star polymers can be successively and, in principle, unlimitedly synthesized by repeating the iterative reaction sequence. Finally, a convenient synthesis of densely branched polymers with starlike structures is presented by the quantitative coupling reaction of living anionic polymers with reactive benzyl halide-functionalized backbone polymers based on a grafting-onto method.KEY WORDS Star Polymer / Asymmetric Star Polymer / Living Anionic Polymerization / Iterative Methodology / Polymeric Coupling Agent / 1,1-Diphenylethylene Derivative / Star polymers are branched polymers in which more than three linear polymer chains are linked together at one end of each chain by a central core or a single branch. They have physical properties in bulk, melt, and solution quite distinct from linear analogues. For this reason, star polymers have been widely studied from both synthetic and theoretical points of view. [1][2][3][4][5][6][7][8][9] It is of course essential to use star polymers with welldefined structures for evaluating fundamental understanding regarding the effect of chain branching on such physical properties.At the present time, the most successful methodologies for the synthesis well-defined regular star polymers have been developed mainly based on coupling reactions of living anionic polymers of styrene and 1,3-dinene monomers with multifunctional chlorosilane compounds as electrophilic coupling agents. A variety of star polymers with a definite number of three to eighteen arms have been synthesized. [10][11][12][13][14][15][16][17][18][19] Furthermore, the successful syntheses of the 32-, 64-, and even 128-arm star polymers by using specially designed carbosilane dendrimers have been reported so far. 20,21 Currently, great attention has been paid to more complex asymmetric star polymers whose arms differ in molecular weight and chemical composition, since star polymers of this type are expected to exhibit interesting and unique physical performance originated from their † To whom correspondence should be addressed.branched architectures as well as heterophase structures. [22][23][24][25][26][27][28][29][30][31][32][33] Synthesis of asymmetric star polymers is generally more difficult than that of regular star polymers. In the synthesis of regular star polymers, for example, their arms can be simultaneously introduced by one reaction. On the other hand, two or more highyielding reactions...

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“…The presence of functional groups along the chains could lead to significant changes in their behavior in the solid state and in solution [6]. Subsequent transformations of these groups may further lead to polymers with desired functionalities [7,8].…”

Section: Introductionmentioning

confidence: 99%

Non-Isothermal Degradation Kinetics of Hybrid Copolymers Containing Thermosensitive and Polypeptide Blocks

Ivanova¹,

Dimitrov²,

Georgieva³

et al. 2012

OJPChem

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Novel, self-associating hybrid copolymers were synthesized via controlled ring-opening polymerization of -carboxyanhydride of Z-L-lysine (Z-L-Lys-NCA), initiated by amino-functional macroinitiators. A poly(N-isopropylacrylamide) (PNIPAm)-based macroinitiator containing 10 mol% of polyoxyethylene grafts and a terminal primary amine group in the form of ammonium hydrochloride (PNIPAm-g-PEО) was synthesized and used to initiate the ammoniummediated ring-opening polymerization of NCA described by Dimitrov and Schlaad [1]. Thus, hybrid copolymers ((PNIPAm-g-PEO)-b-PLys) with controlled molar-mass characteristics and functionality were obtained. The potential applications of PNIPAm-based copolymers in the systems for controlled drug release, immobilization of enzymes and protein purification have aroused great interest in the studies of their properties and behaviour. The thermal stability and thermodynamic properties of the copolymers obtained were studied. The differential thermal analysis of polyfunctional hybrid copolymers (PNIPAm-g-PEO)-b-PLys) showed that thermooxidative destruction occurs in two stages: primary, of the unstable fragments (grafted chains of PEO); and secondary, of the main polymer chains of poly(N-isopropylacrylamide) and poly(L-lysine). The kinetics of thermal degradation was evaluated and the values of the activation energy of the degradation process, changes of Gibbs free energy, enthalpy and entropy for the formation of the activated complex were also calculated.

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Recent advance in syntheses and applications of well-defined end-functionalized polymers by means of anionic living polymerization

Cited by 112 publications

References 54 publications

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

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

Precise Synthesis of Regular and Asymmetric Star Polymers and Densely Branched Polymers with Starlike Structures by Means of Living Anionic Polymerization

Non-Isothermal Degradation Kinetics of Hybrid Copolymers Containing Thermosensitive and Polypeptide Blocks

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