Complex Formations between Surfactants and Polyelectrolytes of the Same Charge on a Water Surface
Bibliographic record
Abstract
The mechanism of complex formation between surfactants and polyelectrolytes with the same charge on the water surface was investigated using molecular dynamics simulations and phase-sensitive sum-frequency generation vibrational spectroscopy. Although complex formation between highly charged surfactants and polyelectrolytes of the same charge is generally expected to be prohibited by the electrostatic repulsive force, our study shows that it is possible to form thermodynamically stable complexes when excess ions are present in the solution. We found that anionic partially hydrolyzed polyacrylamide (HPAM) could interact with anionic sodium dodecyl sulfate (SDS) on a water surface in the presence of salts. With excess Na + ions in the solution, the charge screening effect allows HPAM to weakly interact with SDS via hydrogen bonds. In the presence of divalent Ca 2+ ions, the surfactant and the polymer are strongly coupled by forming Ca 2+ ion bridges and hydrogen bonds. Our calculation shows that the presence of Ca 2+ ions creates a steep binding energy of ∼30 kJ/mol near the water surface. These results were qualitatively verified using phase-sensitive sum-frequency generation vibrational spectroscopy.
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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".