Polystyrene–polyisoprene block copolymers in dilute solutions: Characterization of the conformation by small‐angle neutron scattering

Ionescu, L; Picot, C.; Duplessix, R.; Duval, Michel; Benoît, H.; Lingelser, Jean‐Paul; Gallot, Yves

doi:10.1002/pol.1981.180190702

Cited by 21 publications

(6 citation statements)

References 16 publications

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“…For instance, Prud’homme and Bywater studied poly(styrene- b -isoprene) diblock copolymers by DLS and showed that the two types of chain segments must be separated in solution, especially in poor solvent for the block . In contrast, Ionescu et al studied a similar system by SANS but found no evidence for block segregation in a good solvent for the two blocks, , whereas Han and Mozer arrived at the opposite conclusion while using a similar technique on the same system . More specifically, in the case of amphiphilic copolymers, Tanaka et al investigated poly(styrene- b -methyl methacrylate) copolymers in 2-butanone by DLS and showed that their results were not consistent with a segregated conformation .…”

Section: Resultsmentioning

confidence: 99%

Molecular Weight Determination of Block Copolymers by Pulsed Gradient Spin Echo NMR

et al. 2009

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Matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) is the technique of choice to achieve molecular weight data for synthetic polymers. Because the success of a MALDI-MS analysis critically depends on a proper matrix and cation selection, which in turn relates closely to the polymer chemical nature and size, prior estimation of the polymer size range strongly helps in rationalizing MALDI sample preparation. We recently showed how pulsed gradient spin echo (PGSE) nuclear magnetic resonance could be used as an advantageous alternative to size exclusion chromatography, to rationalize MALDI sample preparation and confidently interpret MALDI mass spectra for homopolymers. Our aim here is to extend this methodology to the demanding case of amphiphilic block copolymers, for which obtaining prior estimates on the Mw values appears as an even more stringent prerequisite. Specifically, by studying poly(ethylene oxide) polystyrene block copolymers of distinct molecular weights and relative block weight fractions, we show how PGSE data can be used to derive the block Mw values. In contrast to homopolymers, such determination requires not only properly recorded calibration curves for each of the polymers constituting the block copolymers but also an appropriate hydrodynamic model to correctly interpret the diffusion data.

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Section: Resultsmentioning

confidence: 99%

Molecular Weight Determination of Block Copolymers by Pulsed Gradient Spin Echo NMR

et al. 2009

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“…Variable contrast small angle neutron scattering was used to study the molecular conformation of styrene-isoprene block copolymers in dilute solutions (82).…”

Section: Light Scatteringmentioning

confidence: 99%

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Fox¹,

Jeffries²

1983

Anal. Chem.

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“…The characterization of the micelles was performed by SANS, DLS, and viscometry. It has been demonstrated that SANS in combination with contrast variation is a powerful method to investigate micellar systems − and it was also shown that the structure of the micelles can be quantitatively evaluated by model fitting to the experimental data. − …”

Section: Introductionmentioning

confidence: 99%

Structural Investigation of Micelles Formed by an Amphiphilic PEP−PEO Block Copolymer in Water

et al. 1997

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Micelles of a poly(ethylene-co-propylene)-block-Poly(ethylene oxide) (PEP−PEO) copolymer in water were investigated by small angle neutron scattering (SANS), dynamic light scattering (DLS), and viscometry. The block copolymer was built of a partially deuterated PEP block and a hydrogeneous PEO block with an overall molecular weight of 11.1 × 103. The SANS measurements were performed at four contrasts in order to get detailed structural information about the micellar aggregates. The different scattering curves could be described very well by a spherical core−shell model with constant density in both parts. The sharp edges of the polymer density distribution were smeared by multiplication with a Gaussian in Q-space. The model yielded a core radius of R C = 176 Å and an overall micellar radius of R M = 294 Å. The smearing ranges were 11 and 32 Å, respectively. The fit further yielded an aggregation number of P = 2430. DLS measurements reveal a narrow monomodal distribution of relaxation frequencies, indicating the existence of only one aggregated species. The obtained hydrodynamic radius, R H = 339 Å, as well as the radius determined by viscosity measurements, R V = 324 Å, are consistent with the result of the model fitting. The unusually large aggregation number could be explained by the large interfacial tension between water and PEP in terms of simple thermodynamic models.

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Polystyrene–polyisoprene block copolymers in dilute solutions: Characterization of the conformation by small‐angle neutron scattering

Cited by 21 publications

References 16 publications

Molecular Weight Determination of Block Copolymers by Pulsed Gradient Spin Echo NMR

Molecular Weight Determination of Block Copolymers by Pulsed Gradient Spin Echo NMR

Air pollution

Structural Investigation of Micelles Formed by an Amphiphilic PEP−PEO Block Copolymer in Water

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