Interactions between cationically modified hydroxyethyl cellulose and oppositely charged surfactants studied by gel swelling experiments—effects of surfactant type, hydrophobic modification and added salt

Employing extensive Monte Carlo computer simulations, we investigate in detail the properties of multichain adsorption of charged flexible polyelectrolytes (PEs) onto oppositely charged spherical nanoparticles (SNPs). We quantify the conditions of critical adsorption—the phase-separation curve between the adsorbed and desorbed states of the PEs—as a function of the SNP surface-charge density and the concentration of added salt. We study the degree of fluctuations of the PE–SNP electrostatic binding energy, which we use to quantify the emergence of the phase subtransitions, including a series of partially adsorbed PE configurations. We demonstrate how the phase-separation adsorption–desorption boundary shifts and splits into multiple subtransitions at low-salt conditions, thereby generalizing and extending the results for critical adsorption of a single PE onto the SNP. The current findings are relevant for finite concentrations of PEs around the attracting SNP, such as the conditions for PE adsorption onto globular proteins carrying opposite electric charges.

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Charge Modification as a Mechanism for Tunable Properties in Polymer–Surfactant Complexes

Polymers ◽

10.3390/polym13162800 ◽

2021 ◽

Vol 13 (16) ◽

pp. 2800

Author(s):

Christopher Hill ◽

Wasiu Abdullahi ◽

Robert Dalgliesh ◽

Martin Crossman ◽

Peter Charles Griffiths

Keyword(s):

Phase Space ◽

Sodium Dodecylsulfate ◽

Phase Behaviour ◽

Hydroxyethyl Cellulose ◽

Charge Ratio ◽

Modified Polymers ◽

Novel Approach ◽

Charged Polymer ◽

Polymer Surfactant ◽

Oppositely Charged

Oppositely charged polymer–surfactant complexes are frequently explored as a function of phase space defined by the charge ratio Z, (where Z = [+polymer]/[−surfactant]), commonly accessed through the surfactant concentration. Tuning the phase behaviour and related properties of these complexes is an important tool for optimising commercial formulations; hence, understanding the relationship between Z and bulk properties is pertinent. Here, within a homologous series of cationic hydroxyethyl cellulose (cat-HEC) polymers with minor perturbations in the degree of side chain charge modification, phase space is instead explored through [+polymer] at fixed Cpolymer. The nanostructures were characterised by small-angle neutron scattering (SANS) in D2O solutions and in combination with the oppositely charged surfactant sodium dodecylsulfate (h- or d-SDS). Scattering consistent with thin rods with an average radius of ∼7.7 Å and length of ∼85 Å was observed for all cat-HEC polymers and no significant interactions were shown between the neutral HEC polymer and SDS (CSDS < CMC). For the charge-modified polymers, interactions with SDS were evident and the radius of the formed complexes grew up to ∼15 Å with increasing Z. This study demonstrates a novel approach in which the Z phase space of oppositely charged polymer–surfactant complexes can be controlled at fixed concentrations.

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Mechanisms of ethyl(hydroxyethyl) cellulose–solid interaction: Influence of hydrophobic modification

Journal of Colloid and Interface Science ◽

10.1016/j.jcis.2005.06.072 ◽

2006 ◽

Vol 293 (2) ◽

pp. 322-332 ◽

Cited By ~ 32

Author(s):

Jing Wang ◽

P. Somasundaran

Keyword(s):

Hydroxyethyl Cellulose ◽

Hydrophobic Modification ◽

Ethyl Hydroxyethyl Cellulose

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Effect of Hydrophobic Modification on Phase Behavior and Rheology in Mixtures of Oppositely Charged Polyelectrolytes

Langmuir ◽

10.1021/la941003q ◽

1996 ◽

Vol 12 (2) ◽

pp. 530-537 ◽

Cited By ~ 53

Author(s):

Krister Thuresson ◽

Svante Nilsson ◽

Björn Lindman

Keyword(s):

Phase Behavior ◽

Hydrophobic Modification ◽

Oppositely Charged

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Binding of SDS to Ethyl(hydroxyethyl)cellulose. Effect of Hydrophobic Modification of the Polymer

The Journal of Physical Chemistry ◽

10.1021/jp9520411 ◽

1996 ◽

Vol 100 (12) ◽

pp. 4909-4918 ◽

Cited By ~ 53

Author(s):

Krister Thuresson ◽

Olle Söderman ◽

Per Hansson ◽

Geng Wang

Keyword(s):

Hydroxyethyl Cellulose ◽

Hydrophobic Modification ◽

Ethyl Hydroxyethyl Cellulose

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Network Formation of Catanionic Vesicles and Oppositely Charged Polyelectrolytes. Effect of Polymer Charge Density and Hydrophobic Modification

Langmuir ◽

10.1021/la049783i ◽

2004 ◽

Vol 20 (11) ◽

pp. 4647-4656 ◽

Cited By ~ 57

Author(s):

Filipe E. Antunes ◽

Eduardo F. Marques ◽

Ricardo Gomes ◽

Krister Thuresson ◽

Björn Lindman ◽

...

Keyword(s):

Charge Density ◽

Network Formation ◽

Hydrophobic Modification ◽

Catanionic Vesicles ◽

Oppositely Charged

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Surfactant Impurities Can Explain the Jones-Ray Effect

10.26434/chemrxiv.5732976 ◽

2018 ◽

Author(s):

Timothy Duignan ◽

Marcel Baer ◽

Christopher Mundy

Keyword(s):

Surface Tension ◽

Electrostatic Potential ◽

Driving Forces ◽

Salt Water ◽

Fundamental Property ◽

Apparent Contradiction ◽

Low Salt ◽

Air Water Interface ◽

Added Salt ◽

Effect Of Surface

<div> <p> </p><div> <div> <div> <p>The surface tension of dilute salt water is a fundamental property that is crucial to understanding the complexity of many aqueous phase processes. Small ions are known to be repelled from the air-water surface leading to an increase in the surface tension in accordance with the Gibbs adsorption isotherm. The Jones-Ray effect refers to the observation that at extremely low salt concentration the surface tension decreases in apparent contradiction with thermodynamics. Determining the mechanism that is responsible for this Jones-Ray effect is important for theoretically predicting the distribution of ions near surfaces. Here we show that this surface tension decrease can be explained by surfactant impurities in water that create a substantial negative electrostatic potential at the air-water interface. This potential strongly attracts positive cations in water to the interface lowering the surface tension and thus explaining the signature of the Jones-Ray effect. At higher salt concentrations, this electrostatic potential is screened by the added salt reducing the magnitude of this effect. The effect of surface curvature on this behavior is also examined and the implications for unexplained bubble phenomena is discussed. This work suggests that the purity standards for water may be inadequate and that the interactions between ions with background impurities are important to incorporate into our understanding of the driving forces that give rise to the speciation of ions at interfaces. </p> </div> </div> </div> </div>

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