Complexes between sodium alginate and cetyltrimethylammonium <i>p</i> -toluenesulfonate: a multi-technique investigation of their formation in solution as a function of pH
Bibliographic record
Abstract
The interaction between the cationic surfactant cetyltrimethylammonium p-toluenesulfonate (CTAT) and a carbohydrate-based biopolymer (sodium alginate) has been investigated at several pH values using surface tension measurements, isothermal calorimetry, turbidimetry, and fluorescence probing experiments. The results indicate that CTAT interacts strongly with sodium alginate at a surfactant concentration that is at least an order of magnitude lower than the critical micelle concentration of pure CTAT in water. Further addition of CTAT leads to fully saturated complexes at a concentration that is not significantly dependent on the solution pH and is surprisingly not much different than the critical micelle concentration (CMC) value of pure CTAT. The excess CMCs (CMC e values) reflect the concentration at which the saturated complex equilibrates with free surfactant and pure surfactant micelles; these values, determined from isothermal calorimetry and surface tension measurements, increase when the solution pH is increased consistent with the expected changes in the degree of ionization of the biopolymer as pH rises. In agreement with our previous paper, the data presented here indicate that the condensation of the surfactant onto the anionic polymer is a complex processes encompassing strong electrostatic interactions, cooperative binding of the amphiphile ions to the polymer backbone, and multiple equilibria among spherical micelles, rod-like micelles, free surfactant ions, and the polymer–surfactant complex.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| 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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".