Scattering from charged macromolecules. - I. Static structure factor

Benmouna, M.; Weill, G.; Benoît, H.

doi:10.1051/jphys:0198200430110167900

Cited by 49 publications

(22 citation statements)

References 17 publications

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“…This exponent is close to the theoretical slope 0.5 for a geometrical model of cylindrically or hexagonally packed infinitely long rods. [114][115][116] In the presence of added salt (NaCl), the electrostatic interactions are screened out and the scattering peaks disappear progressively as the ionic strength is increased revealing the neutral behavior of the system at ionic strengths as low as of 10 À5 mol Á L À1 . These results are illustrated Figure 5.…”

Section: Static Behaviormentioning

confidence: 99%

Rodlike Cellulose Microcrystals: Structure, Properties, and Applications

Lima¹,

Borsali²

2004

Macromol. Rapid Commun.

795

343

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Summary: In this article we present some interesting properties of rodlike cellulose microcrystals (so‐called “whiskers”). These microcrystals can be obtained from different cellulose sources such as wood, cotton, or animal origin. When submitted to acid hydrolysis, the cellulose fibers yield stable aqueous suspensions because of the presence of negative charges on the surface of the microcrystallites during the hydrolysis process. The obtained microcrystals are rod‐shaped particles, the dimensions of which depend on the cellulose origin. For instance, the cotton whiskers have typical dimensions varying from 100 to 300 nm in length, L, and 8 to 10 nm in diameter, d, while those of the tunicate whiskers range from 100 nm to few micrometers in length and 10 to 20 nm in diameter. At very low concentrations, these whiskers are randomly suspended in water and form an isotropic phase. When the concentration reaches a critical value, the whiskers spontaneously display ordered phases showing interesting liquid crystal properties (nematic and chiral nematic). The chiral nematic orders can be retained after evaporation of the solvent (generally water), leaving iridescent films. The reflected color can be controlled by changing either the ionic strength or by applying an electric field. These colloidal particles have been investigated using several techniques including small‐angle neutron scattering (SANS), small angle X‐ray scattering, rheology, and more recently dynamic and static light scattering techniques (DLS and SLS) to highlight their static and dynamic behavior. Because of their geometry, important axis ratio (L/d), and high crystallinity, these rods have been also extensively used to process nanocomposites based on polymer matrices, to reinforce their mechanical properties. All these properties are discussed in this contribution.Rodlike nanocrystals in aqueous suspension (left, Tunicate, 1 wt.‐%) and film (right), observed between cross‐polarizers.magnified imageRodlike nanocrystals in aqueous suspension (left, Tunicate, 1 wt.‐%) and film (right), observed between cross‐polarizers.

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Section: Static Behaviormentioning

confidence: 99%

Rodlike Cellulose Microcrystals: Structure, Properties, and Applications

Lima¹,

Borsali²

2004

Macromol. Rapid Commun.

795

343

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“…Thus normalized scattering intensities Z(q) are expected to merge at sufficiently high q-values. This qualitative argument has been put into quantitative terms by Benmouna et al [36] by considering the influence of the structure factor in the region of low concentrations. If q .…”

Section: Commands Attentionmentioning

confidence: 99%

Conformation and shape of rigid‐rod polyesters substituted with flexible side chains as revealed by small‐angle neutron scattering

et al. 1993

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A small-angle neutron study of liquid crystalline main chain polyesters with flexible side chains is presented. Investigations in solution have been performed using protonated material dissolved in deuterated tetrahydrofuran and deuterated nitrobenzene. To determine the conformation in bulk, mixtures of deuterated and protonated material have been investigated at ambient and at elevated temperature. For this purpose, a route for the synthesis of fully deuterated polyesters has been developed. It is shown that the form factor measured in solution is compatible with an extended, rod-like conformation. Investigations in bulk show that a plate-like conformation is adopted under these conditions. This observation is in full agreement with earlier findings from structural studies which indicate that in bulk the side chains of a given main chain are located in a plane; i.e., the polyester molecule assumes a plate-like shape. Thus the present investigation demonstrates that there is a pronounced change of conformation when going from solution to bulk. The reason for this change are the packing constraints exerted by the neighbouring molecules in the bulk.

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“…The model described by Benmouna [15] was used, for spherical partides with Coulomb repulsive forces producing a correlation hole. The structural factor is given by:…”

Section: ( )Oomentioning

confidence: 99%

Formamide, a water substitute XIV (1) waterless microemulsions 8. Structural analysis by X-ray scattering of CTAB aggregates in formamide and in the microemulsion system (formamide, CTAB, isooctane, 1-butanol)

Auvray

Petipas

Anthore

et al. 1987

Colloid & Polymer Sci

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X-ray scattering was used to analyse the structures of aggregates of CTAB in various formamide-containing media.Firstly, CTAB micelles were detected in formamide solutions. A spherical micelle model was proposed; at values close to the CMC, smaller micelles were observed in formamide than in water.Secondly, the structure of microemulsions in the isooctane-rich zone of the system (formamide/CTAB = 2, isooctane, 1-butanol) was studied by X-ray scattering. The structure was found to be quite different in this zone from that normally observed in aqueous microemulsions. Structures compatible with small filaments of formamide were detected. The results were related to previous measurements of electrical conductivity.

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Scattering from charged macromolecules. - I. Static structure factor

Cited by 49 publications

References 17 publications

Rodlike Cellulose Microcrystals: Structure, Properties, and Applications

Rodlike Cellulose Microcrystals: Structure, Properties, and Applications

Conformation and shape of rigid‐rod polyesters substituted with flexible side chains as revealed by small‐angle neutron scattering

Formamide, a water substitute XIV (1) waterless microemulsions 8. Structural analysis by X-ray scattering of CTAB aggregates in formamide and in the microemulsion system (formamide, CTAB, isooctane, 1-butanol)

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