Solvent separation by amphiphiles: Heads and tails synergies
Bibliographic record
Abstract
• Tetrahydrofuran (THF) is miscible in water due to hydrogen bonding. • Fatty acids and alcohols are miscible in THF and separate it from water. • Carboxylic acid heads interact with THF more strongly than OH heads. • Fatty acids are more effective than fatty alcohols at separation. • The tails are important because they impede water-amphiphile interactions. Tetrahydrofuran (THF) is miscible in water due to hydrogen (H) bonding. Fatty acids and alcohols are miscible in THF and separate it from water, yielding bulk layers or emulsions. Separation is more effective with fatty alcohols and acids having intermediate solubility in THF-water mixtures. Fatty acids are more effective than fatty alcohols at separation, because carboxylic acid heads interact with THF more strongly than OH heads, as highlighted by activity coefficients estimated using COSMO RS (Conductor-like Screening Model for Realistic Solvents). These are lower with fatty acids than fatty alcohols. Infrared spectroscopy shows that THF disrupts H bonding of fatty alcohols, while enhancing H bonding of fatty acids. Moreover, activity coefficients are lower for acetic acid (representative of the heads) than alkanes (representative of the tails), indicating that THF interacts more strongly with the carboxylic heads than the tails. Therefore, we propose that fatty alcohols self-assemble into micelles with the heads pointing outwards and reside in the THF phase to prevent mixing with water. Small angle X ray scattering shows that oleic acid (unsaturated) self-assembles into micelles, similar to stearic acid (saturated), but is more disordered. While fatty acids interact with THF primarily through their heads, tails matter because they impede water-fatty acid interactions. Acetic acid does not induce separation. Fatty alcohols also self-assemble into micelles, which swell with water. Water H bonds the alcohol heads more strongly than THF, which instead interacts with the tails. With no or little water, longer tails enhance fatty alcohol solubility, yielding smaller clusters.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".