Small-angle X-ray scattering studies of semidilute polystyrene-cyclohexane solutions

Xie, Yonglin; Ludwig, Karl; Bansil, Rama; Gallagher, Patrick; Cao, Xingxiang; Morales, G.

doi:10.1016/0378-4371(96)00218-x

Cited by 13 publications

(11 citation statements)

References 29 publications

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“…Evidence of such a discrepancy has already been observed for a large variety of polymeric gels or concentrated systems [34][35][36] and have been ascribed to the presence of heterogeneities in the structure of the gel. 34 If the correlation length, z, among the inhomogeneous regions is larger than the correlation length, x, of the crosslinks, a structure factor S ex that takes into account of the scattering excess can be added to the Ornstein-Zernike contribution: 37…”

Section: Resultsmentioning

confidence: 92%

Physico-chemical and structural properties of hydrogels formed by chitosan, in the presence and absence of poly(vinylpyrrolidone) and sodium decylsulfate

Mangiapia

Frielinghaus

D’Errico

et al. 2007

Phys. Chem. Chem. Phys.

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The structure of chemically-crosslinked chitosan and chitosan-poly(vinylpyrrolidone) (PVP) hydrogels is investigated by means of the combined use of small-angle neutron scattering (SANS), electron paramagnetic resonance spectroscopy (EPR), intradiffusion, and swelling degree measurements. These hydrogels may be described in terms of an inhomogeneous structure composed by polymer-rich and polymer-poor regions. The polymer-rich regions, whose correlation distance zeta is ranged between approximately 600 and approximately 850 A, are, in turn, characterized by the presence of a network formed by the chemical crosslinks, with a mean correlation distance xi approximately 90 A. The structures of chitosan and chitosan-PVP hydrogels have also been analyzed in the presence of sodium decylsulfate micelles that could provide a multidomain system useful, in principle, for drug delivery applications. Both SANS and EPR measurements show that sodium decylsulfate micelles do not significantly interact with both the gels. Finally, intradiffusion and swelling degree measurements show an improved hydrophilicity of chitosan-PVP gels, even further magnified by the presence of C10OS surfactant.

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Section: Resultsmentioning

confidence: 92%

Physico-chemical and structural properties of hydrogels formed by chitosan, in the presence and absence of poly(vinylpyrrolidone) and sodium decylsulfate

Mangiapia

Frielinghaus

D’Errico

et al. 2007

Phys. Chem. Chem. Phys.

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“…Similar inhomogeneities were also observed in SAXS measurements on moderately concentrated polystyrene solutions in dioctylphthalate 51 and in cyclohexane. 52 The slow mode was also observed by Burchard 53 and Brown et al 54 Although the origin of this mode is not fully understood, it may reflect an association between chains. The phenomenon is probably unrelated to the block copolymer nature of the chains, instead it may be related to the entangled transient network in concentrated solutions.…”

Section: Figurementioning

confidence: 80%

Dynamics of solutions of triblock copolymers in a selective solvent: Effect of varying copolymer concentration

Koňák

Fleischer

Tuzar

et al. 2000

J. Polym. Sci. B Polym. Phys.

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“…Details of the normalization and deconvolution process will be discussed in another paper. 18 4.1. Equilibrium Measurements.…”

Section: Data Analysis and Resultsmentioning

confidence: 99%

“…Deviations from the Ornstein-Zernicke function have been repeatedly reported in equilibrium studies of semidilute polymer solutions. A number of experiments [14][15][16][17][18] revealed an "excess scattering" at low wavenumbers in semidilute polymer solutions which indicates enhanced concentration fluctuations in these systems. Although many attempts have been made to account for this effect, no conclusive explanation has been reached.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Time-Resolved Small-Angle X-ray Scattering Studies of Spinodal Decomposition Kinetics in a Semidilute Polystyrene−Dioctyl Phthalate Solution

et al. 1996

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Synchrotron-based time-resolved small-angle X-ray scattering was used to measure the early-stage spinodal decomposition kinetics in a highly viscous semidilute solution of polystyrene in dioctyl phthalate. Although strong nonlinearities in the kinetics were observed, a linear theory analysis could fit the evolution of the structure factor at short times and low wavenumbers. Nonlinearities become significant earlier at higher wavenumbers, which is consistent with recent computer simulation studies. From the linear theory analysis, the exponential relaxation rate of the structure factor R(q) was found to be linear in q 2 in the low-wavenumber region of the experiments, in agreement with mean-field theory for spinodal decomposition in polymer solutions. The wavenumber-dependent Onsager transport coefficient Λ(q), which is the Fourier transform of the nonlocal mobility in a polymer system, was determined to scale as q -4 . This q dependence, which is stronger than that predicted by existing theory, may be related to entanglement effects.

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Small-angle X-ray scattering studies of semidilute polystyrene-cyclohexane solutions

Cited by 13 publications

References 29 publications

Physico-chemical and structural properties of hydrogels formed by chitosan, in the presence and absence of poly(vinylpyrrolidone) and sodium decylsulfate

Physico-chemical and structural properties of hydrogels formed by chitosan, in the presence and absence of poly(vinylpyrrolidone) and sodium decylsulfate

Dynamics of solutions of triblock copolymers in a selective solvent: Effect of varying copolymer concentration

Time-Resolved Small-Angle X-ray Scattering Studies of Spinodal Decomposition Kinetics in a Semidilute Polystyrene−Dioctyl Phthalate Solution

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