Interaction between Surfactants and Colloidal Latexes in Nonpolar Solvents Studied Using Contrast-Variation Small-Angle Neutron Scattering

Smith, G. Frederick; Alexander, Shirin; Brown, Paul; Gillespie, David A. J.; Grillo, Isabelle; Heenan, Richard K.; James, Craig; Kemp, Roger; Rogers, Sarah E.; Eastoe, Julian

doi:10.1021/la500331u

Cited by 25 publications

(59 citation statements)

References 52 publications

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“…A fit to these data gives an SLD for the latexes of ρ n =(1.1 ± 0.1) × 10 −6Å−2 . This is consistent with recent experimental measurements of the SLD of a similar PMMA latex [74] and the values used in other studies [58,69,70]. The scattering of the latexes has been analyzed using a model for core-shell spheres under different contrast conditions, and this confirmed that the scattering length density is higher in the center of the latex than in the stabilizer shell [73,82,83].…”

Section: Nm Diameter Latexessupporting

confidence: 90%

“…Fluorescence energy-transfer studies have shown that small molecules can distribute throughout the cores [103][104][105]. Other small molecules, such as residual hexane solvent [106] or surfactant charging agents [74,76], can also be distributed throughout the cores of the latexes. Given that molecules are able to partition throughout the volume of the latexes, the core polymers could be highly porous and therefore significantly less dense than the pure polymer.…”

Section: Discussionmentioning

confidence: 99%

“…As an example, in dilute dispersions, the small amount of scattering from the PHSA shells is not significant in contrast-matched solvent [73,74], whereas in concentrated dispersions, whether in contrast-matched solvent or for SESANS measurements [79], the scattering from the stabilizer shells can be significant. The results in this study show how complementary structural information of colloids of different sizes in nonpolar solvents can be obtained.…”

Section: Discussionmentioning

confidence: 99%

“…Small-angle neutron scattering (SANS) has been used to study the composition and interaction of latexes by the Ottewill group at the University of Bristol [51,58,[67][68][69][70] and others [71,72] as well as to study the distribution of surfactants in charged latexes [73][74][75][76]. Small-angle X-ray scattering (SAXS) has also been used to study the interaction of such PMMA latexes [77,78].…”

Section: Nm Diameter Latexesmentioning

confidence: 99%

See 3 more Smart Citations

The internal structure of poly(methyl methacrylate) latexes in nonpolar solvents

Smith

Finlayson

Gillespie

et al. 2016

Journal of Colloid and Interface Science

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Section: Nm Diameter Latexessupporting

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Nm Diameter Latexesmentioning

confidence: 99%

See 2 more Smart Citations

The internal structure of poly(methyl methacrylate) latexes in nonpolar solvents

Smith

Finlayson

Gillespie

et al. 2016

Journal of Colloid and Interface Science

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“…Instead, x-ray scattering studies [23] showed a fascinating phase behavior of Wigner crystals, including a body-centered-cubic (bcc) phase at low concentration, and a solid-solid transition to a face-centered-cubic (fcc) phase at higher densities [15][16][17][18]24,25]. It is also possible to induce charge on particles in nonaqueous solvents through the addition of charge control agents [21,[26][27][28]. However, in this case, there is strong coupling between the charge on the particle surface and the ions in solution.…”

mentioning

confidence: 99%

Crystallization and reentrant melting of charged colloids in nonpolar solvents

Kanai

Boon

et al. 2015

Phys. Rev. E

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We explore the crystallization of charged colloidal particles in a nonpolar solvent mixture. We simultaneously charge the particles and add counterions to the solution with aerosol-OT (AOT) reverse micelles. At low AOT concentrations, the charged particles crystallize into body-centered-cubic (bcc) or face-centered-cubic (fcc) Wigner crystals; at high AOT concentrations, the increased screening drives a thus far unobserved reentrant melting transition. We observe an unexpected scaling of the data with particle size, and account for all behavior with a model that quantitatively predicts both the reentrant melting and the data collapse. Colloidal particles can spontaneously form structures that exhibit long-range ordered states, making them a fascinating system for fundamental studies of crystal phase behavior [1][2][3][4]. The majority of studies focus on colloids which model the hard-sphere interaction, a strong repulsion that prevents particles from overlapping, whose range is restricted to contact [5]. Hard-sphere crystallization is driven through purely entropic effects, and the phase behavior is well studied [5][6][7][8][9]. Typically, the colloids used for these studies are stericallystabilized polymeric particles in nonaqueous solvents, which can match both the density ρ and refractive index n of the particles, enabling confocal microscopy to be used for these investigations. Even earlier studies focused on charged particles, where crystallization is driven by strong long-range repulsive interactions arising from Coulombic charges on the particles [1,[10][11][12][13][14][15][16][17][18][19][20][21][22]. These studies were performed on particles in aqueous solvents, which makes charge effects much easier to induce, but precludes index matching, limiting the use of optical techniques except at very low densities. Instead, x-ray scattering studies [23] showed a fascinating phase behavior of Wigner crystals, including a body-centered-cubic (bcc) phase at low concentration, and a solid-solid transition to a face-centered-cubic (fcc) phase at higher densities [15][16][17][18]24,25]. It is also possible to induce charge on particles in nonaqueous solvents through the addition of charge control agents [21,[26][27][28]. However, in this case, there is strong coupling between the charge on the particle surface and the ions in solution. Charge-induced crystallization should still be expected, although new behavior may also occur as a consequence of this coupling. Nevertheless, these systems have never been investigated experimentally, and the range of potential behavior has not yet been explored.In this Rapid Communication, we investigate the crystallization behavior of colloidal particles in nonpolar solvents. By adding aerosol-OT (AOT) reverse micelles, we both charge the particles and add ions to the solution. As AOT concentration increases from zero, the system undergoes a first transition from fluid to a charge-stabilized bcc Wigner crystal, and * Corresponding author: plu@fas.harvard.edu then a second solid-sol...

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Structure and conductivity of AOT solutions in n‐hexadecane‐chloroform mixtures

et al. 2020

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The structure and conductivity of AOT (sodium bis(2-ethylhexyl) sulfosuccinate) solutions (2.5 × 10 −4-2.5 × 10 −1 M) in n-hexadecane-chloroform mixture at the chloroform concentration from 50 to 100 vol% were studied. The diffusion ordered spectroscopy NMR study revealed that in the indicated range, the observed hydrodynamic diameter of micelles depends only on the AOT concentration and does not depend on the chloroform content. Molar fractions of free AOT molecules and those aggregated into micelles were calculated using the Lindman's law: at concentrations above 2.5 × 10 −1 М, the solutions contain mostly the micelles, whereas at concentrations below 2.5 × 10 −4 M, the solutions contain AOT molecules. The transition region contains both the AOT molecules and the micelles. Conductivity measurements were used to determine free charge carriers in the bulk of solutions and their contributions to conductivity.

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Interaction between Surfactants and Colloidal Latexes in Nonpolar Solvents Studied Using Contrast-Variation Small-Angle Neutron Scattering

Cited by 25 publications

References 52 publications

The internal structure of poly(methyl methacrylate) latexes in nonpolar solvents

The internal structure of poly(methyl methacrylate) latexes in nonpolar solvents

Crystallization and reentrant melting of charged colloids in nonpolar solvents

Structure and conductivity of AOT solutions in n‐hexadecane‐chloroform mixtures

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