Synthesis of cyclic polyethers

Ishizu, Koji; Akiyama, Yukina

doi:10.1016/s0032-3861(96)00669-6

Cited by 16 publications

(13 citation statements)

References 16 publications

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“…Recently Ishizu and Akiyama have reported the cyclization of poly(ethylene glycol) by reaction of its sodium salt with 1,4-dibromobutane. 20 Remarkably they report cyclization with no chain extension even at relatively high concentrations of glycol (10 -2 -10 -3 mol dm -3 ). We have repeated their procedure many times without success.…”

Section: Introductionmentioning

confidence: 97%

Large Cyclic Poly(oxyethylene)s: Chain Folding in the Crystalline State Studied by Raman Spectroscopy, X-ray Scattering, and Differential Scanning Calorimetry

Cooke

Viras

et al. 1998

Macromolecules

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Crystalline cyclic poly(oxyethylene)s with number-average molar masses (M n) of 4000, 6000, and 10000 g mol -1 were studied by wide-angle (WAXS) and small-angle (SAXS) X-ray scattering, highfrequency and low-frequency laser-Raman spectroscopy, and differential scanning calorimetry (DSC). The subcell of the crystalline cyclic polymers was the same as that of high-molar-mass poly(oxyethylene). Cyclic polymers of Mn ) 4000 or 6000 g mol -1 crystallized in their twice-folded conformation under the conditions investigated, but the cyclic polymer of Mn )10000 g mol -1 crystallized in a four-times-folded conformation when cooled from its melt and in a twice-folded conformation when crystallized slowly at high temperature. Comparison is made with the properties of corresponding linear poly(oxyethylene) dimethyl ethers.

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Section: Introductionmentioning

confidence: 97%

Large Cyclic Poly(oxyethylene)s: Chain Folding in the Crystalline State Studied by Raman Spectroscopy, X-ray Scattering, and Differential Scanning Calorimetry

Cooke

Viras

et al. 1998

Macromolecules

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“…Vitali and Masci first synthesized cyclic poly(ethylene oxide) (cPEO) in 8% yield via ring closing of linear poly(ethylene oxide) (PEO). Using more favorable ring closing conditions, Yu et al , improved the cPEO yield to 93%, and Ishizu and Akiyama synthesized cPEO by intramolecular Williamson etherification with near-quantitative conversion. Additional reports have described the grafting of hydrophobic components to cPEO to afford amphiphilic polymers. , An alternative strategy to prepare water-soluble or stimuli-responsive cyclical polymers includes grafting hydrophilic components to hydrophobic ring polymers to adjust their water solubility …”

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confidence: 99%

“…Despite the few examples reported in the literature, there remains much to improve upon in water-soluble polymers with unique topologies. For example, most of the cyclic water-soluble polymers prepared to date require ring closing of water-soluble linear polymers. ,− This method requires high dilution and suffers from the inherent presence of linear impurities that accompany incomplete cyclization or oligomerization. , Moreover, any postpolymerization modification of cyclic polymers must be conducted with consideration of the linkage used to accomplish ring closing . Ring expansion, another common method for cyclic polymer synthesis, does not require dilution; ,,, however, because this approach is limited to a few select catalyzed polymerization mechanisms, monomer diversity and functionality can be limited.…”

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confidence: 99%

pH-Responsive Water-Soluble Cyclic Polymer

et al. 2019

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Cyclic polymers possess different properties compared to their linear analogues of the same molecular weight, such as smaller hydrodynamic volumes and higher glass transition temperatures (T g ). Cyclic poly(4-ethynylanisole) (cPEA) was synthesized via a catalytic ring-expansion of 4-ethynylanisole. The catalyst employed was a tungsten complex supported by a tetraanionic pincer ligand. Evidence of the cyclic topology comes from gel permeation chromatography, dynamic light scattering, static light scattering, and solution viscometry. Demethylation of cPEA with boron tribromide affords cyclic poly(4-ethynylphenol) (cPEP-OH). cPEP-OH exhibits pH-responsive water solubility, being soluble in aqueous solutions at elevated pH and becoming insoluble under acidic conditions. The linear equivalent of cPEP-OH was also synthesized, and it exhibits similar pH responsiveness.

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“…In brief, cyclic PEG2000 (8, Scheme 3) was prepared by slow addition of the corresponding PEG and p-toluene sulfonyl chloride, both dissolved in anhydrous THF, into a largevolume THF:n-heptane (3:1) containing sufficient amount of powdered KOH. The purpose of the poor solvent (n-heptane) was to improve ring closure by reducing the end-to-end distance of the polymer coil and thus to enhance cyclization [13].…”

Section: Resultsmentioning

confidence: 99%

“Length and breadth” polyrotaxane structures—a new concept in three‐dimensional polymeric systems

Azzam

Peppas

Słomkowski

et al. 2002

Polymers for Advanced Techs

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This work describes the synthesis and characterization of rotaxane‐crosslinked polymers using macrocyclic poly(ethylene glycol) (PEG) attached to a vinyl moiety. Diacyl chlorides (fumaryl or itaconyl) and PEG400 were condensed under high dilution conditions to yield the corresponding macrocyclic monomers. These were purified by column chromatography and identified by mass spectroscopy utilizing MALDI‐TOF technique and 1H‐NMR. Radical polymerization in bulk of these macrocyclic monomers using benzoyl peroxide as initiator, resulted in soft polymers which are soluble in various organic solvents. Under the same conditions, insoluble gels were obtained by copolymerization of the ring‐substituted vinyl monomers with either hydrophobic vinyl monomers (methyl methacrylate, MMA) or with a hydrophilic vinyl monomer (2‐hydroxy ethyl methacrylate, HEMA). These results indicate that crosslinking was obtained due to threading of linear chains through macrocycles which act as crosslinkers. The swelling ratios of the gels indicated a correlation between the molar ratios of the macrocycle and the linear chain incorporated with it. Copyright © 2003 John Wiley & Sons, Ltd.

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Synthesis of cyclic polyethers

Cited by 16 publications

References 16 publications

Large Cyclic Poly(oxyethylene)s: Chain Folding in the Crystalline State Studied by Raman Spectroscopy, X-ray Scattering, and Differential Scanning Calorimetry

Large Cyclic Poly(oxyethylene)s: Chain Folding in the Crystalline State Studied by Raman Spectroscopy, X-ray Scattering, and Differential Scanning Calorimetry

pH-Responsive Water-Soluble Cyclic Polymer

“Length and breadth” polyrotaxane structures—a new concept in three‐dimensional polymeric systems

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