Invalidity of deriving interparticle distance in clay–water systems using the experimental structure factor maximum obtained by small-angle scattering

Shang, Chaoqun; Rice, James A.

doi:10.1016/j.jcis.2004.06.032

Cited by 7 publications

(6 citation statements)

References 37 publications

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“…SAXS curves from a series of NIPAAM–Laponite solutions (with clay contents ≤2 wt %) are shown in Figure S5. As expected from dilute dispersions of randomly oriented thin discs, the scattering intensity in the middle- q range follows a power law (i.e., I ( q ) ∝ q –α , where α = 2) . The scattering curve from a 1.0 wt % Laponite–H 2 O solution without monomer, also present in Figure S5, practically overlaps with that of the 1.0 wt % solution with monomer, demonstrating the negligible contribution from the monomer to the overall SAXS signal.…”

Section: Resultssupporting

confidence: 59%

“…As expected from dilute dispersions of randomly oriented thin discs, the scattering intensity in the middle-q range follows a power law (i.e., I(q) ∝ q −α , where α = 2). 27 The scattering curve from a 1.0 wt % Laponite−H 2 O solution without monomer, also present in Figure S5, practically overlaps with that of the 1.0 wt % solution with monomer, demonstrating the negligible contribution from the monomer to the overall SAXS signal. Three of the curves, 1.0, 1.5, and 2.0 wt %, were fitted using the form factor for thin discs 28 (eq 1), where R and 2H are the radius and thickness of the particles, respectively, J 1 (x) is the first-order Bessel function, α is the angle between the axis of the disc and the scattering vector q, (ρ e,clay − ρ e,H 2 O ) is the electron density contrast between the Laponite platelets and water, N clay is the number of clay platelets per unit volume, and v clay is the volume of a single disc.…”

Section: Resultsmentioning

confidence: 86%

“…I(q) ∝ q -α , where α = 2. 27 The scattering curve from a 1.0 wt.% Laponite-H 2 O solution without monomer, also presented in Figure S5, is practically overlapping with that of the 1.0 wt.% solution with monomer, demonstrating the negligible contribution from the monomer to the overall SAXS signal. Three of the curves, 1.0, 1.5 and 2.0 wt.%, were fitted using the form factor for thin discs 28 (eq.…”

Section: Small Angle X-ray Scattering (Saxs)mentioning

confidence: 81%

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Oxygen-Controlled Phase Segregation in Poly(N-isopropylacrylamide)/Laponite Nanocomposite Hydrogels

et al. 2012

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The combination of nanoparticles and polymers into nanocomposite gels has been shown to be a promising route to create soft materials with new or improved properties. In the present work we have made use of Laponite nanoparticles in combination with a poly(N-isopropylacrylamide) (PNIPAAM) polymer, and describe a phenomenon taking place during polymerization and gelling of this system. The presence of small amounts of oxygen in the process induce two distinctly separated phases, one polymer rich and one polymer deficient water-clay phase. Complex interactions between clay, oxygen and the polymer are found to govern the behavior of these phases. It is also observed that the initial clay concentration can be used to directly control the volume fraction of the polymer-deficient phase. The dynamics of the phase boundary is found to be dependent on water penetration, and in general to present 2 a non-Fickian behavior. An approach using video recording for monitoring hydrogel swelling is also presented and its advantages addressed.

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Section: Resultssupporting

confidence: 59%

Section: Resultsmentioning

confidence: 86%

Section: Small Angle X-ray Scattering (Saxs)mentioning

confidence: 81%

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Oxygen-Controlled Phase Segregation in Poly(N-isopropylacrylamide)/Laponite Nanocomposite Hydrogels

et al. 2012

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“…∆ρ, P(q), and S exp (q) are the scattering length density difference between the clay particles and the matrix, the form factor of the clay particles, and the experimental structure factor, respectively [20][21][22][23][24]. Here the magnitude of the wavevector q is defined by the following equation.…”

Section: Structures Of Clay/paas Hydrogelsmentioning

confidence: 99%

Mechanical, Swelling, and Structural Properties of Mechanically Tough Clay-Sodium Polyacrylate Blend Hydrogels

Takeno

Kimura

Nakamura

2017

Gels

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Abstract:We investigated the mechanical, swelling, and structural properties of mechanically tough clay/sodium polyacrylate (PAAS) hydrogels prepared by simple mixing. The gels had large swelling ratios, reflecting the characteristics of the constituent polymer. The swelling ratios initially increased with the increase of the swelling time, and then attained maximum values. Afterwards, they decreased with an increase of the swelling time and finally became constant. An increase in the clay concentration lead to a decrease in the swelling ratios, whereas an increase in the PAAS concentration lead to an increase in the swelling ratios. Tensile measurements indicated that the toughness for clay/PAAS (M w = 3.50 × 10 6 ) gels was several hundred times larger than that of clay/PAAS (M w = 5.07 × 10 5 ) gels, i.e., the use of ultra-high molecular weight PAAS is essential for fabricating mechanically tough clay/PAAS blend hydrogels. Synchrotron small-angle X-ray scattering (SAXS) results showed that the SAXS intensity measured at small scattering angles decreased with an increase in the clay concentration, indicating that the interparticle interactions were more repulsive at higher concentrations. The decrease of the scattering intensity at high clay concentrations was larger for the clay/PAAS (M w = 5.07 × 10 5 ) gel system than for the clay/PAAS (M w = 3.50 × 10 6 ) gel system.

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“…The values, in general, decreased by increasing the polyP dose and remained negative in the entire concentration range studied. This tendency can be explained by referring to previous studies on LRD-phosphate systems. , It was also suggested that the progressive adsorption of polyP on the positively charged edges of LRD (as illustrated in Scheme , middle), leads to an increase in the overall negative particle charge at higher polyP doses . Variations in the degree of polymerization did not yield any significant changes in the electrophoretic mobilities.…”

Section: Resultsmentioning

confidence: 63%

The Impact of Polyphosphates on the Colloidal Stability of Laponite Particles

Katana,

Baptista,

Schneider

et al. 2024

J. Phys. Chem. B

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The effect of polyphosphate (polyP) adsorption on the colloidal properties of disc-shaped laponite (LRD) particles was examined in aqueous dispersions with a focus on elucidating the interparticle forces that govern the colloidal stability of the systems. The charge and aggregation rate data of bare LRD exhibited an ionic strength-dependent trend, confirming the presence of double-layer repulsion and van der Waals attraction as major surface interactions. The charge of LRD particles significantly increased in magnitude at elevated polyP concentrations as a result of polyP adsorption and subsequent overcharging of the positively charged sites on the edges of the LRD discs. A transition from stable to unstable LRD colloids was observed with increasing polyP doses indicating the formation of aggregates in the latter systems due to depletion forces and/or bridging interactions induced by dissolved or adsorbed polyP, respectively. The degree of phosphate polymerization influenced neither the charge nor the aggregation mechanism. The findings clearly confirm that polyP adsorption was the driving phenomenon to induce particle aggregation in contrast to other clay types, where phosphate derivatives act as dispersion stabilizing agents. This study provides valuable insights into the early stages of aggregation in colloidal systems involving LRD and polyPs, which have a crucial role in predicting further material properties that are important to designing LRD-polyP composites for applications such as potential phosphate sources in chemical fertilizers.

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Invalidity of deriving interparticle distance in clay–water systems using the experimental structure factor maximum obtained by small-angle scattering

Cited by 7 publications

References 37 publications

Oxygen-Controlled Phase Segregation in Poly(N-isopropylacrylamide)/Laponite Nanocomposite Hydrogels

Oxygen-Controlled Phase Segregation in Poly(N-isopropylacrylamide)/Laponite Nanocomposite Hydrogels

Mechanical, Swelling, and Structural Properties of Mechanically Tough Clay-Sodium Polyacrylate Blend Hydrogels

The Impact of Polyphosphates on the Colloidal Stability of Laponite Particles

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