Preparation and characterization of pure oligo(ethylene glycol)s. 2

Kinugasa, Shinichi; Takatsu, Akiko; Nakanishi, Hiroshi; Nakahara, Hisae; Hattori, Shigeru

doi:10.1021/ma00045a003

Cited by 31 publications

(26 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, only a limited number of examples have been known as the linear and uniform (monodisperse) oligomers with a degree of polymerization (DP) exceeding 50. Those examples are oligoethylenes 1 -3 and oligo( oxyethylene )s, 4 both of which were synthesized by the repeated coupling of the homogeneous building-blocks.…”

mentioning

confidence: 99%

Isotactic and Syndiotactic Pentacontamers (50mers) of Methyl Methacrylate Obtained by Fractionation with Preparative SFC: The GPC Analysis of the 50mers and Their Stereocomplex

Ute

Miyatake

Osugi

et al. 1993

Polym J

View full text Add to dashboard Cite

ABSTRACT:Highly isotactic (it-) and highly syndiotactic 2Smers and SOmers of MMA have been isolated from it-and st-PMMAs, respectively, by means of the preparative supercritical fluid chromatography (SFC) using carbon dioxide/ethanol as mobile phase and silica gel as stationary phase. The 2Smers and SOmers with definite molecular weight (2561 and 5064) were useful as the standard materials in GPC for the calibration of molecular weight and the direct evaluation of instrumental spreading. The it-SOmer eluted faster than the st-SOmer in the GPC using THF as eluent. When a solution of a I: I mixture of the it-and st-SOmers in THF was subjected to the GPC measurement at 3°C, the chromatogram showed two peaks at the elution volumes corresponding to the 50 and lOOmers. The elution peak for the lOOmer suggests that the it-and st-SOmers form stereocomplex in a I : I ratio. The peak area for the stereocomplex varied from 0 to 9.0% of the whole chromatographic peaks, depending on the conditions (time and temperature) under which the mixed solution of the it-and st-SOmers was allowed to stand. Stereocomplex formation was not observed for a mixture of the it-and st-25mers by similar GPC experiments.

show abstract

mentioning

confidence: 99%

Isotactic and Syndiotactic Pentacontamers (50mers) of Methyl Methacrylate Obtained by Fractionation with Preparative SFC: The GPC Analysis of the 50mers and Their Stereocomplex

Ute

Miyatake

Osugi

et al. 1993

Polym J

View full text Add to dashboard Cite

show abstract

“…The experimental details were described in our previous paper. 8 In Figure I, an analytical GPC chromatogram for the pure OEG18 sample is illustrated together with the one for a commercial PEG standard sample.…”

Section: Methodsmentioning

confidence: 99%

“…7 In our previous study, we described a method for preparing a pure oligoethylene glycol, i.e., octadecaethylene glycol (OEG 18). 8 It is of interest to determine characteristic parameters such as the molecular weight M of OEG 18 by light scattering, because a compound of definite molecular weight can be used as a standard sample for calibrating light scattering instruments. 9 Additionally, a series of pure PEO samples such as OEG18 can also be used as ideal molecular weight standards; for example, in gel permeation chromatography (GPC), calibration curves between molecular weights of PEO and elution volumes will be established more precisely by using these pure samples than by commercial standard PEOs.…”

mentioning

confidence: 99%

Preparation and Characterization of Pure Oligoethylene Glycols I.

Kinugasa

Hayashi

Hattori

1990

Polym J

Self Cite

View full text Add to dashboard Cite

ABSTRACT:The solution properties of a pure oligoethylene glycol, i.e., octadecaethylene glycol (OEG 18), in acetonitrile have been studied by light scattering and small-angle X-ray scattering (SAXS) measurements. No strong downturn at small angles have been observed in the Zimm plot of light scattering data, indicating that OEG18 molecules disperse molecularly in solution. The weight-average molecular weight Mw ( =833) obtained by light scattering measurements is in good agreement with the expected molecular weight M ( = 810.9) of OEG 18. The radius of gyration (S 2 ) 112 ( =9.6±0.4A) has been determined bySAXS, yielding the characteristic ratio Cn=4.8 ±0.4.KEY WORDS Poly(ethylene oxide)/ Oligoethylene Glycol/ Light Scattering / Small-Angle X-Ray Scattering/ Radius of Gyration/ Characteristic Ratio/ Poly(ethylene oxide) (PEO) is a simple polymer with unusual properties. 1 One of the characteristic features of PEO is that the polymer tends to aggregate in various solvents. Elias and Lys 2 pointed out that PEO aggregates in some solvents and light scattering data show a strong downturn at small angles in Zimm plots for PEO in methanol, 3 dimethylformamide,4 and water,5 indicating the presence of some aggregates in these good solvents.To discuss unperturbed chain dimensions of polymers, the characteristic ratio en= (R 2 ) 0 /nl2 is often used, where (R 2 ) 0 is the unperturbed mean-square end-to-end distance, n the number of skeletal bonds, and l2 the average of the square of their length. 6 The value of en can be estimated from the unperturbed mean-square radius of gyration (S 2 ) 0 ( = (R 2 ) 0 /6 for large n) obtained by a scattering method such as light scattering, small-angle X-ray scattering (SAXS), and small-angle neutron scattering (SANS In our previous study, we described a method for preparing a pure oligoethylene glycol, i.e., octadecaethylene glycol (OEG 18). 8

show abstract

“…[70] The isolated products included unreacted 18-mer, a 36-mer formed through a 1:1 reaction, a 54-mer and a 90-mer formed through a reaction with the disodium salt contained in the reaction mixture as an impurities. The 54-mer was isolated by preparative SEC.…”

Section: Uniform Polymers From Stepwise Reactionsmentioning

confidence: 99%

“…These results indicate that the uniform poly(oxyethylene) can be used as a reliable molecular weight standard. [70] The preparation by a convergent growth method of dendritic macromolecules that are nearly uniform with respect to molecular weight, and their use as molecular weight standards, has also been reported. [71,72] Uniform dendrimers can also be used as standards of molecular size.…”

Section: Uniform Polymers From Stepwise Reactionsmentioning

confidence: 99%

Synthetic Uniform Polymers and Their Use for Understanding Fundamental Problems in Polymer Chemistry

Hatäda

Kitayama

Ute

et al. 2004

Macromol. Rapid Commun.

View full text Add to dashboard Cite

Summary: A uniform polymer is a polymer composed of molecules that are uniform with respect to molecular weight and constitution. Besides natural uniform polymers such as nucleic acids and polypeptide, synthetic uniform polymers have been obtained by a variety of approaches. In particular, a combination of living polymerization and supercritical fluid chromatography (SFC) separation is one of the promising ways for the preparation of uniform polymers. End‐functionalized uniform polymers enabled us to prepare uniform polymer architectures such as block, graft, comb, and star polymers. Their use for understanding the fundamental problems in polymer chemistry is discussed; topics include crystallization of polymers, chain conformation in solution, and association of stereoregular polymers in solution.

show abstract

Preparation and characterization of pure oligo(ethylene glycol)s. 2

Cited by 31 publications

References 7 publications

Isotactic and Syndiotactic Pentacontamers (50mers) of Methyl Methacrylate Obtained by Fractionation with Preparative SFC: The GPC Analysis of the 50mers and Their Stereocomplex

Isotactic and Syndiotactic Pentacontamers (50mers) of Methyl Methacrylate Obtained by Fractionation with Preparative SFC: The GPC Analysis of the 50mers and Their Stereocomplex

Preparation and Characterization of Pure Oligoethylene Glycols I.

Synthetic Uniform Polymers and Their Use for Understanding Fundamental Problems in Polymer Chemistry

Contact Info

Product

Resources

About