Phase Transitions in Spread Monolayers of Cellulose Ethers
Bibliographic record
Abstract
Cellulose ethers containing alkyl side chains of varying length were prepared from (2-hydroxypropyl)cellulose and alkyl bromides. Two different synthetic methods were employed. The average degree of alkyl substitution of the product polymers ranges from 1.8 to 2.8, as determined from 1 H NMR spectroscopy. Surface pressure−area isotherms recorded for spread monolayers depend on temperature, side-chain length, and degree of substitution. Most striking is the temperature dependence. For certain samples, a constant pressure transition is clearly evident in isotherms recorded at higher temperatures. Upon modest cooling, the plateau vanishes, although changes in slope indicate that a phase transition persists. Results are interpreted in terms of partial crystallization in interdigitated side chains. For samples that exhibit a constant pressure transition, the plateau pressure increases with decreasing the subphase temperature. Thermodynamic analysis yields positive entropy and enthalpy changes for the transition, consistent with a transition from a monolayer to a less ordered bilayer. An energy change associated with the transition is calculated as ΔE = 60 ± 15 kJ mol - 1 . LB films transferred to solid substrates were characterized by polarized infrared spectroscopy. These results suggest that the alkyl side chains exist in a predominately all-trans conformation in the LB films.
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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) | 0.000 | 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) | 0.001 | 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".