Thermodynamic Stability and the Origins of Incongruent and Strongly Coupled Diffusion in Solutions of Micelles, Solubilizates, and Microemulsions
Bibliographic record
Abstract
Ternary mutual diffusion coefficients ( D ik ) are reported for aqueous solutions of dodecylsulfobetaine (1) + hexadecylsulfobetaine (2) mixed zwitterionic micelles. Cross-coefficient D 12 reaches values almost as large as the main D ii coefficients, indicating strongly coupled fluxes. As the surfactant concentrations are raised and the extent of micelle formation increases, values of the determinant D 11 D 22 − D 12 D 21 of the D ik matrix drop sharply. Previous studies have shown that the thermodynamic stability constraint μ 11 μ 22 − μ 12 μ 21 ≥ 0 on the concentration derivatives μ ik = ∂μ i /∂ C k of the chemical potentials causes D 11 D 22 − D 12 D 21 to vanish at critical points and phase separation boundaries. Consequently, the cross-coefficients become similar in magnitude to the main coefficients. Prompted by the insight that might be gained by demonstrating an analogy between diffusion in micelle solutions and diffusion near phase separation, a model of mixed-micelle formation based on multiple monomer association equilibria [ n A 1 + m B 1 = A n B m ] is used to show that μ 11 μ 22 − μ 12 μ 21 drops almost to zero with increasing extent of micelle formation. This result, which is generalized to other association colloids, points to thermodynamics as the underlying cause of strongly coupled fluxes, incongruent diffusion, and other remarkable features of diffusion in solutions of mixed micelles, solubilizates, and microemulsions. A molecular interpretation of diffusion in these systems, consistent with the Gibbs−Duhem and Onsager reciprocal relations, is developed by relating the D ik coefficients and the Onsager L ik transport coefficients to the concentrations and the mobilities of the free monomers and various A n B m species.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".