Synthesis of well‐defined macrocyclic block copolymers using living coupling agent method

Ma, Jingjing

doi:10.1002/masy.19950910105

Cited by 15 publications

(16 citation statements)

References 11 publications

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“…The connection of the two end blocks through the peptide bond leads to an additional expansion of the whole molecule and, therefore, higher intrinsic viscosity. The higher value of the ratio (0.79) found for a cyclic diblock copolymer of S and I39 fortifies our assumption.…”

Section: Resultssupporting

confidence: 81%

Synthesis of a model cyclic triblock terpolymer of styrene, isoprene, and methyl methacrylate

Pantazis

Schulz

Hadjichristidis

2002

J. Polym. Sci. A Polym. Chem.

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The synthesis of a model cyclic triblock terpolymer [cyclic(S‐b‐I‐b‐MMA] of styrene (S), isoprene (I), and methyl methacrylate (MMA) was achieved by the end‐to‐end intramolecular amidation reaction of the corresponding linear α,ω‐amino acid precursor [S‐b‐I‐b‐MMA] under high‐dilution conditions. The linear precursor was synthesized by the sequential anionic polymerization of S, I, and MMA with 2,2,5,5‐tetramethyl‐1‐(3‐lithiopropyl)‐1‐aza‐2,5‐disilacyclopentane as an initiator and amine generator and 4‐bromo‐1,1,1‐trimethoxybutane as a terminator and carboxylic acid generator. The separation of the unreacted linear polymer from the cyclic terpolymer was facilitated by the transformation of the unreacted species into high molecular weight polymers by the evaporation of the reaction solvent and the continuation of the reaction under high‐concentration conditions. The intermediate materials and the final cyclic terpolymer, characterized by size exclusion chromatography, vapor pressure osmometry, thin‐layer chromatography, IR and NMR spectroscopy, exhibited high molecular weight and compositional homogeneity. Dilute‐solution viscosity measurements were used as an additional proof of the cyclic structure. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1476–1483, 2002

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Section: Resultssupporting

confidence: 81%

Synthesis of a model cyclic triblock terpolymer of styrene, isoprene, and methyl methacrylate

Pantazis

Schulz

Hadjichristidis

2002

J. Polym. Sci. A Polym. Chem.

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“…Ma 31 has used a similar approach for the synthesis of cyclic PS-b-PBd copolymers. In this synthetic route, the cyclization was performed by adding dropwise a linking agent solution to the diluted R,ω-difunctional living triblock copolymer.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Characterization of Model Cyclic Block Copolymers of Styrene and Butadiene. Comparison of the Aggregation Phenomena in Selective Solvents with Linear Diblock and Triblock Analogues

Iatrou¹,

Hadjichristidis²,

Meier³

et al. 2002

Macromolecules

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The synthesis and characterization of model cyclic diblock copolymers of styrene (St) or perdeuterated styrene (St-d8) and butadiene (Bd) are presented. Since conventional methods of characterization cannot separate completely the cyclic copolymer from its linear precursor, differences in the micellar behavior were used as a method for investigation of their purity. For this purpose, in addition to the cyclic and linear triblock copolymers, two linear diblocks with similar compositions, and molecular weight equal or half of the cyclic diblocks, were also synthesized. The synthetic approach of the cyclics involved the reaction of (1,3-phenylene)bis(3-methyl-1-phenylpentylidene)dilithium initiator with butadiene in the presence of sec-BuOLi, followed by polymerization of . The cyclization of the resulting R,ω-difunctional triblock copolymer was performed by using bis(dimethylchlorosilyl)-ethane, under high dilution conditions. The copolymers were characterized by size exclusion chromatography, membrane osmometry, NMR and UV spectrometry, and viscometry. The micelles formed in the selective solvents n-decane (for PBd) and dimethylformamide (for PS-d 8) were characterized by smallangle neutron scattering and dynamic light scattering. It was found that the aggregation number of the cyclic copolymers was the smallest among the different macromolecular architectures. Moreover, the SANS data for the triblocks in n-decane indicated the presence of 37% dangling chains which did not appear in the data for the corresponding cyclic copolymers. Considering that 5% of dangling chains is possible to be detected, it proves that the cyclic copolymers are at least 87% pure. A scaling model was used in order to justify the difference in the aggregation numbers between the four different copolymers.

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“…[77][78][79][80][81][82] The general synthetic strategy consisted of a sequential anionic polymerization of two monomers yielding bisanionic A-B-A triblock copolymers which were in situ cyclized with suitable coupling agent (refer Scheme 10). The formulas of three cyclic diblock copolymers prepared in this way are compiled in Scheme 17.…”

Section: -1351-70mentioning

confidence: 99%

Cyclic polymers: Synthetic strategies and physical properties

Kricheldorf

2009

J. Polym. Sci. A Polym. Chem.

401

442

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Syntheses of cyclic polymers including cyclic homopolymers, cyclic block copolymers, sun-shaped polymers, and tadpole polymers are discussed on the basis of a differentiation between synthetic methods and synthetic strategies (e.g., polycondensation, ring-ring equilibration, or ring-expansion polymerization). Furthermore, all synthetic methods are classified as kinetically or thermodynamically controlled reactions. Characteristic properties of cyclic polymers such as smaller hydrodynamic volume, lower melt viscosities, and higher thermostabilities are compared to the properties of their linear counterparts. Furthermore, the nanophase separation of cyclic diblock copolymers is discussed.

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Synthesis of well‐defined macrocyclic block copolymers using living coupling agent method

Cited by 15 publications

References 11 publications

Synthesis of a model cyclic triblock terpolymer of styrene, isoprene, and methyl methacrylate

Synthesis of a model cyclic triblock terpolymer of styrene, isoprene, and methyl methacrylate

Synthesis and Characterization of Model Cyclic Block Copolymers of Styrene and Butadiene. Comparison of the Aggregation Phenomena in Selective Solvents with Linear Diblock and Triblock Analogues

Cyclic polymers: Synthetic strategies and physical properties

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