On-Line SEC-NMR Analysis of the Stereocomplex of Uniform Isotactic and Uniform Syndiotactic Poly(methyl methacrylate)s

Ute, Koichi; Niimi, Ryo; Matsunaga, Morikatsu; Hatäda, Koichi; Kitayama, Tatsuki

doi:10.1002/1521-3935(20011001)202:15<3081::aid-macp3081>3.0.co;2-z

Cited by 36 publications

(31 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A typical example is the study on the stereocomplex formation between it-and st-PMMAs in solution. [4,[14][15][16][17][18]117] It is well known that it-and st-PMMA chains associate to form a crystalline stereocomplex when mixed in certain solvents such as toluene, N,N 0 -dimethylformamide, and acetone, or annealed in the solid state.…”

Section: Uniform Polymers For Studying the Association Of Polymer Molmentioning

confidence: 99%

“…Relative intensity of the two peaks was 26:74, indicating that a majority of the uniform PMMAs exists in the complex part. [117] When a similar experiment was carried out using THF as the eluent, only a small part ($9%) of the uniform PMMAs formed the stereocomplex. [4,14] These indicate that acetone is a much more complex-forming solvent than THF.…”

Section: Uniform Polymers For Studying the Association Of Polymer Molmentioning

confidence: 99%

“…6 ]acetone at À15 8C. [117] Online SEC-1 H NMR analysis [121,122] at À15 8C of a 1.12:1.00 mixture of st-and it-46mers (M ¼ 4663) [117] clearly indicated that the peak with larger elution time is due to the nonassociated 46-mers, mostly the it-46mer, and the other peak with smaller elution time the stereocomplex. Figure 28a is the 1 H NMR spectrum recorded at the elution time where the stereocomplex was eluting.…”

Section: Uniform Polymers For Studying the Association Of Polymer Molmentioning

confidence: 99%

“…st-/it-¼ 1:1 and 2:1) coexist in the mixtures. [117] The unimodal, narrow profile of the elution curve (apparent M w =M n ¼ 1.01, see Figure 27c) due to the stereocomplex indicates that both the complexes with 1:1 (M ¼ 9 326) and 2:1 (M ¼ 13 989) compositions have the hydrodynamic volumes corresponding to that of it-PMMA with M % 7000. This can be ascribed to higher compactness of stereocomplex particles compared with nonassociated linear it-PMMA in solution.…”

Section: Uniform Polymers For Studying the Association Of Polymer Molmentioning

confidence: 99%

See 3 more Smart Citations

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

Hatäda

Kitayama

Ute

et al. 2004

Macromol. Rapid Commun.

Self Cite

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

Section: Uniform Polymers For Studying the Association Of Polymer Molmentioning

confidence: 99%

Section: Uniform Polymers For Studying the Association Of Polymer Molmentioning

confidence: 99%

Section: Uniform Polymers For Studying the Association Of Polymer Molmentioning

confidence: 99%

Section: Uniform Polymers For Studying the Association Of Polymer Molmentioning

confidence: 99%

See 2 more Smart Citations

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

Hatäda

Kitayama

Ute

et al. 2004

Macromol. Rapid Commun.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The st-/it-compositions of the stereocomplex in the mixtures were determined to be 1.61-1.94, indicating the coexistence of at least two types of stereocomplexes with different compositions (for example, st-/it-¼ 1/1 and 2/1). 12 The uniform PMMA was also used to perform atomic force microscopic observations of stereocomplex formation at the waterair interface by Kumaki et al,13 who demonstrated the occurrence of molar-mass recognition in PMMA complex formation.…”

Section: Introductionmentioning

confidence: 99%

Uniform poly(methyl methacrylate) stereostars: synthesis, separation and stereocomplex formation

Nishiura

Abe

Kitayama

2010

Polym J

Self Cite

View full text Add to dashboard Cite

Isotactic (it-) and syndiotactic (st-) uniform poly(methyl methacrylate)s (PMMAs) with hydroxyl end groups were isolated by supercritical fluid chromatography (SFC) and reacted with benzene-1, 3, 5-tricarbonyl trichloride. Two types of uniform threearm star-PMMAs with different stereoregular arms, [it/it/st]-and [it/st/st]-3-star-PMMAs, that is, 'stereostar PMMAs', were isolated by SFC from the product mixture (According to IUPAC nomenclature for nonlinear polymers, star PMMA with three arms is named 3-star-PMMA. In this paper, the stereoregularity of the three arms is designated as [it/it/st], for example, and thus, the polymer is named [it/it/st]-3-star-PMMA. By analogy to 'stereoblock' PMMAs, these star PMMAs are termed 'stereostar' PMMAs). proposed another model known as a double-stranded helix model, in which a helix of the it-PMMA chain with a smaller radius is surrounded by an st-PMMA helical chain with a larger radius.Recently, Kumaki et al. 5 demonstrated multistranded models based on atomic force microscopic observation of PMMA stereocomplexes formed at the air-water interface through two-dimensional crystallization, in which the double-stranded it-PMMA helix was surrounded by the st-PMMA helix. Both helix models developed in that work indicated that a 1:2 ratio of associated monomeric units in it-and stPMMAs is required for complex formation. Although most experimental results indicate that the stoichiometry of the stereocomplex is st-/it-¼2/1, 2,6 a number of contradictory results have been reported about the stoichiometry, 7 with some results suggesting st-/it-¼1/1 8 or st-/it-¼1.5/1. 9,10 Previous stoichiometry results were related to the ratio of associated monomeric units or the mass fractions of it-and st-PMMAs. To obtain a molecular-level understanding of the mechanism and stoichiometry of stereocomplex formation, however, the critical factor should be the stoichiometry of the complex, that is, the ratio of it-and st-PMMA molecules, rather than the monomeric unit ratio.

show abstract

Chemical Detectors

2009

Modern Size‐Exclusion Liquid Chromatography

View full text Add to dashboard Cite

On-Line SEC-NMR Analysis of the Stereocomplex of Uniform Isotactic and Uniform Syndiotactic Poly(methyl methacrylate)s

Cited by 36 publications

References 15 publications

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

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

Uniform poly(methyl methacrylate) stereostars: synthesis, separation and stereocomplex formation

Chemical Detectors

Contact Info

Product

Resources

About