Small angle neutron scattering by semi-dilute solutions of polyelectrolyte

Nierlich, Martine; Williams, C. E.; Boué, François; Cotton, J. P.; Daoud, M.; Famoux, B.; Jannink, G.; Picot, C.; Moan, M.; Wolff, C.; Rinaudo, Marguerite; Gennes, P. G. de

doi:10.1051/jphys:01979004007070100

Cited by 254 publications

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“…In these events, the scattering signal will reflect not only the effect of interparticle correlations but also the effect of internal structure of the macromolecular ions. These combined effects may give rise to a peak in the form of the scattering signal [3,7,8,9] which is different from the oscillations observed in g(R ) or equivalently in its Fourier transform. In view of the fact that this behaviour may sometimes lead to misinterpretation [10,11], we believe it is worthwhile to emphasize once more the point that the maximum observed in many experiments [3,[7][8][9][10][11] may be interpreted using the idea of correlation hole effect.…”

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confidence: 93%

Scattering from charged macromolecules. - I. Static structure factor

1982

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Abstract. -In this paper we investigate the variation of the coherent static structure factor S(q) with momentum transfer q for a solution of charged macromolecules at finite concentration with and without added salt. We consider in particular the cases of spherical and rodlike macromolecules. We introduce an effective potential model to account for the Coulomb repulsion between macromolecular ions and thence, we are able to interpret the peak observed experimentally in S(q) using a simple correlation hole argument.

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confidence: 93%

Scattering from charged macromolecules. - I. Static structure factor

1982

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“…We analyze here the inter chain scattering S IC = S/S 1 . For good solvent PEs experiments [16], theory [17], and simulations [18] fig. 4 we have plotted the density dependence of q * in poor solvent for different chain lengths.…”

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confidence: 99%

Structure of polyelectrolytes in poor solvent

2002

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PACS. 61.25.Hq -Macromolecular and polymer solutions. PACS. 36.20.Ey -Polymer molecules -conformation. PACS. 87.15Aa -Theory and modeling; computer simulation.Abstract. -We present molecular dynamics simulations on strongly charged polyelectrolytes in poor solvent. The resulting pearl-necklace conformations are analyzed in detail. Fluctuations in the number of pearls and their sizes lead only to small signatures in the form factor and the force-extension relation, which is a severe obstacle for experimental observations. We find that the position of the first peak in the structure factor varies with the monomer density as ≈ ρ Polyelectrolytes (PEs) are polymers that carry ionizable groups that dissociate ions in aqueous solution. Technical applications range from viscosity modifiers, precipitation agents, superabsorbers to leak protectors [1]. In biochemistry and molecular biology they are of great importance because virtually all proteins, as well as DNA, are PEs.Many PEs contain a non-polar hydrocarbon backbone, for which water is a poor solvent. Therefore, in aqueous solution, there is a competition between the tendency to precipitate, the Coulomb interaction and the entropic degrees of freedom. This can lead to elongated strings of locally collapsed structures (pearls). Such necklace conformations have been predicted on the basis of scaling arguments in ref.[2] for a weakly charged single chain PE, and have been confirmed by simulations using the Debye-Hückel approximation [2,3] and with explicit counterions [4]. The formation of the necklace structure is due to the Rayleigh instability of a charged droplet, which leads to a split once a critical charge is reached. The size of the pearls is determined by the balance between electrostatic repulsion and surface tension. The distance between two pearls is governed by the balance of the electrostatic pearl-pearl repulsion and the surface tension. However, there is up to now no clear experimental proof for the existence of necklace chains [5,6]. Our previous papers [4] dealt with smaller system sizes and showed that necklaces exist also in the presence of counterions and exhibit a variety of conformational transitions as a function of density. The focus of the present paper is to analyze by extensive computer simulations in detail three possible experimental observables, namely the form factor, the structure factor and the force-extension relation, which can be probed by scattering and AFM techniques. Analyzing the fluctuations of necklace structures we find an extended coexistence regime between different necklace structures and broad distributions for the pearl sizes and the pearl-pearl distances that smear out the necklace signatures. In addition we find that the peak in the structure factor of the solution scales proportional to c EDP Sciences

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“…In such regime of concentration, the chains interact and are much interpenetrated. Former scattering measurements were done on PSSNa solutions where all chains where labeled with respect to the solvent, using Small Angle Neutron Scattering (SANS [6]) as well as X rays (SAXS, [14][15]). The obtained quantity is called "total scattering"; it displays a maximum, the well known "polyelectrolyte peak" in absence of salt.…”

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confidence: 99%

Pearl-Necklace-Like Chain Conformation of Hydrophobic Polyelectrolyte: a SANS Study of Partially Sulfonated Polystyrene in Water

2007

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The form factor of partially sulfonated polystyrene PSSNa (degree of sulfonation f =1, 0.72, 0.64 and 0.36), at polymer concentration 0.17M and 0.34M, without or with added salt (0 M, 0.34M, & 0.68M), is measured by Small Angle Neutron Scattering using the Zero Average Contrast method. The total scattering function is also measured, allowing us to extract the distinct interchain function and an apparent structure factor. The main result is the behavior of the form factor which shows contributions of spherical entities as well as extended chain parts. This is striking for 0.64, while for f = 0.36 the sphere contribution is more dominant. The conformation does not depend on polymer concentration. When salt is added, the sphere sizes do not vary, but the contribution Spiteri et al. Form factor of partially sulfonated polystyrene 2 attributed to the stretched parts does vary very much like for fully sulfonated PSSNa. Discussion of the interchain contribution permits to establish the level of interpenetration: solutions are interpenetrated for f= 0.64, and at the limit for f=0.36. The theoretical pearl necklace model appears very suitable to modeling the results. Comparisons are made with analytical calculation and simulation data of pearl necklace. While the respective roles of Rayleigh transition, heterogeneous architecture, and strong hydrophobicity of non sulfonated PS monomers remain under discussion, the data give an accurate three dimensional image of the pearl necklace in solution.

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Small angle neutron scattering by semi-dilute solutions of polyelectrolyte

Cited by 254 publications

References 10 publications

Scattering from charged macromolecules. - I. Static structure factor

Scattering from charged macromolecules. - I. Static structure factor

Structure of polyelectrolytes in poor solvent

Pearl-Necklace-Like Chain Conformation of Hydrophobic Polyelectrolyte: a SANS Study of Partially Sulfonated Polystyrene in Water

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