Anionic polymerization of <i>n</i>‐hexyl isocyanate with monofuctional initiators. Synthesis of well‐defined diblock copolymers with styrene and isoprene

Zorba, Georgia; Vazaios, Aggelos; Pitsikalis, Marinos; Hadjichristidis, Nikos

doi:10.1002/pola.20831

Cited by 15 publications

(8 citation statements)

References 36 publications

(35 reference statements)

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“…The sodium ion trapped in the crown ether allowed rapid dissociation of the ion pair (anion of polymer chain end and sodium cation) and led to fast propagation as well as suppression of backbiting due to the extended chain conformation caused by the bulky cation complex associating with the amidate. The living character of the polymerization was confirmed by preparing block copolymers with octyl isocyanate. , An alternative approach to the controlled anionic polymerization of isocyanates by steric hindrance is addition of sodium tetraphenylborate (NaBPh 4 ), which contains a non-nucleophilic anion. − This additive interacts with the amidate ion (as initiated by sodium naphthalenide), thereby limiting dissociation of the ion pair in polar solvents. Although the polymerization rate and polymer yield were slightly lower (89% in 10 min), the stability of the ion pair formed between NaBPh 4 and the propagating amidate ions prevented irreversible termination .…”

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confidence: 99%

100th Anniversary of Macromolecular Science Viewpoint: Polymerization of Cumulated Bonds: Isocyanates, Allenes, and Ketenes as Monomers

et al. 2020

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Polymer chemistry offers exciting opportunities to tailor the properties of soft materials through control of the composition of the polymers and their interaction with each other, additives, and surfaces. Ongoing advances in the synthesis of polymeric materials demonstrate the drive for materials with tailored properties for enhanced performance in the next generation of materials and devices. One class of small molecules that can serve as monomers in chain growth polymerization are cumulated double bonds of the general form XYZ. The three most common classes of these molecules are isocyanates (NCO), allenes (CCC), and ketenes (CCO), each of which has been explored as monomers under a variety of conditions. The orthogonality of the two pi bonds of the cumulated double bonds (i.e., lack of conjugation) enables the formation of different polymer backbones from a single monomer, provided the regioreactivity is controlled. This Viewpoint outlines the use of these three cumulated double bonds as monomers, illustrating success and current limitations to established polymerization methods. We then provide an outlook to the future of cumulated double bonds as monomers for the generation of tailored polymer compositions.

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confidence: 99%

100th Anniversary of Macromolecular Science Viewpoint: Polymerization of Cumulated Bonds: Isocyanates, Allenes, and Ketenes as Monomers

et al. 2020

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“…The polymer synthesis was accomplished through anionic and coordination polymerization techniques as previously described in the literature [44][45][46][47][48][49][50].…”

Section: Polymer Synthesismentioning

confidence: 99%

“…The diblock copolymers having polystyrene (PS) and PHIC blocks were synthesized either by anionic (SH121/90/10 and SH187/92/8) or by coordination polymerization techniques (SH14/3/97, SH7.5/9/91, SH19.5/11/89 and SH14/18/82) [44][45][46][47][48][49][50]. The samples are symbolized as SH followed by numbers denoting the sample's molecular weight (in KDa), the % wt content is PS and the % wt content in PHIC.…”

Section: Micellization Behavior Of Ps-b-phic Sh Block Copolymers In mentioning

confidence: 99%

“…Thus, polyisocyanates possess an extended 8/3 helical conformation instead of a restricted coplanar conformation [43]. Block copolymers with polystyrene (PS) and polyisoprene (PI) [44][45][46], triblock copolymers, pentablock terpolymers [47], graft copolymers, star polymers, star-block copolymers, miktoarm stars and block-graft copolymers [48][49][50] have been synthesized based either on anionic [51] or coordination polymerization of n-hexyl isocyanate, HIC employing half-Titanocene complexes [52][53][54][55][56][57]. Polyisocyanates have found tremendous applications in nanoscience and materials science as degradable and chiral recognition materials, optical switches, liquid crystals, etc.…”

Section: Introductionmentioning

confidence: 99%

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Micellization Behaviour of Linear and Nonlinear Block Copolymers Based on Poly(n-hexyl isocyanate) in Selective Solvents

et al. 2020

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Block copolymers have attracted significant scientific and economic interest over the last decades due to their ability to self-assemble into ordered structures both in bulk and in selective solvents. In this work, the self-assembly behaviour of both linear (diblocks, triblocks and pentablocks) and nonlinear (miktoarm stars and a block-graft) copolymers based on poly(n-hexyl isocyanate), PHIC, were studied in selective solvents such as n-heptane and n-dodecane. A variety of experimental techniques, namely static and dynamic light scattering, dilute solution viscometry and atomic force microscopy, were employed to study the micellar structural parameters (e.g., aggregation number, overall micellar size and shape, and core and shell dimensions). The effect of the macromolecular architecture, the molecular weight and the copolymer composition on the self-assembly behaviour was studied. Spherical micelles in equilibrium with clusters were obtained from the block copolymers. Thermally stable, uniform and spherical aggregates were found from the triblock copolymers. The poly(n-hexyl isocyanate)-b-polyisoprene-b-poly(n-hexyl isocyanate),-HIH copolymers tend to adopt closed loop conformation, leading to more elongated cylindrical-type structures upon increasing the concentration. Clustering effects were also reported in the case of the pentablock terpolymers. The topology of the blocks plays an important role, since the poly(n-hexyl isocyanate)-b-polystyrene-b-polyisoprene-b-polystyrene-b-poly(n-hexyl isocyanate), HSISH terpolymer shows intermicellar fusion of spherical micelles, leading to the formation of extended networks. The formation of spherical micelles in equilibrium with clusters was obvious in the case of the miktoarm stars, whereas the block-graft copolymer shows the existence of mainly unimolecular micelles.

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“…Some coordination polymerizations make a living polymerization of isocyanates possible, and the polymer yield varies from 74% to 95% after 24 h polymerization [10][11][12][13] . Hadjichristidis et al synthesized functionalized homo and block copolymers of n-HexNCO and complex macromolecular architectures based on nHexNCO using functionalized anionic initiators or organotitanium catalysts, and organotitanium macroinitiator [14][15][16] . Furthermore, rare earth catalysts, especially rare earth organometallic compounds, are also used for the polymerization of isocyanates.…”

Section: Introductionmentioning

confidence: 99%

Room temperature polymerization of alkyl isocyanates catalyzed by rare earth Schiff base complexes

Yang

Shen

2009

Sci. China Ser. B-Chem.

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The polymerization of alkyl isocyanates catalyzed by rare earth chloride salen complexes/triisobutyl aluminum (Ln(H 2 salen) 2 Cl 3 ·2C 2 H 7 OH/Al(i-Bu) 3 ) at room temperature was investigated. The influences of ligand structure, catalyst composition, polymerization temperature, polymerization time, the concentration of catalyst and monomer, and the polymerization solvent on the polymerization of isocyanates were studied. It was found that under the polymerization conditions, examined La(H 2 salen A ) 2 Cl 3 ·2C 2 -H 7 OH/Al(i-Bu) 3 (H 2 salen A = N,N'-disalicylideneethylene diamine) is a fairly high efficient catalyst for the polymerization of n-hexyl isocyanate (n-HexNCO) to prepare high molecular weight poly(n-hexyl isocyanate) (PHNCO) with narrower molecular weight distribution at room temperature. PHNCO could be prepared with yield of 74.0%, number-average molecular weight (M n ) of 40.20×10 4 and MWD of 1.79 under the following optimum conditions: [Al]/[La] = 30 (molar ratio), [n-HexNCO]/[La] = 100 (molar ratio), [n-HexNCO] = 3.43 mol/L polymerization at 20℃ for 12 h in toluene.In the same polymerization conditions, poly (n-octyl isocyanate) (PONCO) with yield of 67.3%, and poly(n-butyl isocyanate) (PBNCO) with yield of 45.5%, could be prepared respectively. The kinetics of the polymerization of n-HexNCO was also investigated and found to be first-order with respect to both monomer and catalyst concentrations.rare earth catalyst, Schiff base complex, polymerization, alkyl isocyanate

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Anionic polymerization of n‐hexyl isocyanate with monofuctional initiators. Synthesis of well‐defined diblock copolymers with styrene and isoprene

Cited by 15 publications

References 36 publications

100th Anniversary of Macromolecular Science Viewpoint: Polymerization of Cumulated Bonds: Isocyanates, Allenes, and Ketenes as Monomers

100th Anniversary of Macromolecular Science Viewpoint: Polymerization of Cumulated Bonds: Isocyanates, Allenes, and Ketenes as Monomers

Micellization Behaviour of Linear and Nonlinear Block Copolymers Based on Poly(n-hexyl isocyanate) in Selective Solvents

Room temperature polymerization of alkyl isocyanates catalyzed by rare earth Schiff base complexes

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