Aggregation of syndiotactic poly(methyl methacrylate) in dilute solutions

Sedláček, B.; Spěváček, Jiří; Mrkvičková, L.; Stejskal, Jaroslav; Horská, Jitka; Baldrián, Josef; Quadrat, Otto

doi:10.1021/ma00134a051

Cited by 26 publications

(22 citation statements)

References 7 publications

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“…This principal observation has already been made by Spevacek et al [18,19] when studying the aggregation of polymethylacrylates and was further used by different groups [20,21] in polymer NMR, but to the best of our knowledge not for the detection of the gelation point. Decreasing signal intensity of organogelator molecules in the gel state has also been described by Escuder et al [22] Very advanced NMR methods using double quantum methodology have recently been applied to this problem as well.…”

Section: Resultsmentioning

confidence: 75%

NMR study of the gelation of a designed gelator

Brand¹,

Nolis²,

Richter³

et al. 2008

Magnetic Reson in Chemistry

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The gelation of a designed gelator was investigated by different NMR methods, which showed a clear thermal hysteresis. Two very simple approaches for the NMR determination of the gelation point are suggested. One involves the observation of the NMR integral, and the other records the ratio of the diffusion coefficients between the gelator and the solvent. Differential behavior of the gelator protons are interpreted as a hint that a part of the gelator molecule might still be flexible as in the dissolved state.

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Section: Resultsmentioning

confidence: 75%

NMR study of the gelation of a designed gelator

Brand¹,

Nolis²,

Richter³

et al. 2008

Magnetic Reson in Chemistry

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“…WipLirHt (12) A typical Porod plot is given in Figure 3 for the 45 "C system. As expected, a linear variation is obtained which gives (rH2)1I2 = 2.23 nm.…”

Section: Resultsmentioning

confidence: 99%

Molecular Structure and Thermal Behavior of Poly(methyl methacrylate) Thermoreversible Gels and Aggregates

Fazel¹,

Brûlet²,

Guenet³

1994

Macromolecules

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The formation of thermoreversible gels and aggregates of poly(methy1 methacrylate) (PMMA) has been investigated as a function of temperature in two different solvents, i.e., bromobenzene and o-xylene. The molecular structure and the thermal behavior have been determined and correlated. It is again shown that the systems are composed of rigid, interconnected cylinders characterized by a two-population distribution as far as the transverse cylinder radius, rH, is concerned: a majority of cylinders with r H = 1.5 f 0.1 nm and a minority of cylinders with rH = 3.5-4.0 nm. When the gelation sets in, the proportion of the second population is seen to increase substantially at the expense of the first population. These results are interpreted with a fringed-micelle model in which the physical junctions consist of the large-radius population of cylinders. The results and conclusions are discussed in the light of a solvated double-helical conformation.

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“…40 Stereoregular poly(methyl methacrylate)s, (s-PMMA)s have a strong tendency to form the ordered aggregated structures in solution. [41][42][43][44][45] In addition to aggregates of the socalled stereocomplex of PMMA which arise on mixing solutions of isotactic and syndiotactic (PMMA)s, attention has been devoted in recent years to the self-aggregation of s-PMMA alone, using NMR and infrared spectroscopy. It was found that the rate of self-aggregation increases with decreasing temperature and with increasing concentration of the solution.…”

Section: Atactic Pmma/n-butyl Chloride Systemmentioning

confidence: 99%