Temperature- and Tension-Induced Coil−Globule Transition of Poly(<i>N</i>-isopropylacrylamide) Chains in Water and Mixed Solvent of Water/Methanol
Bibliographic record
Abstract
The concept of cooperative dehydration, defined as the simultaneous dissociation of the water molecules bound in correlated sequences to a polymer chain, has been applied to study the collapse of a poly( N -isopropylacrylamide) (PNIPAM) chain upon heating in aqueous solutions. We examined the applicability of this concept in three situations: (i) PNIPAM in water (in the absence of added force), (ii) PNIPAM in water subjected to a tension applied to the chain ends, and (iii) PNIPAM in a mixed solvent of water and a second water-miscible solvent. The transition becomes sharper as the cooperativity parameter of hydration increases. The tension−elongation curve of a hydrated chain at various temperatures, calculated following an approach similar to the classical theory of coil−helix transition, presents a flat plateau corresponding to the tension for which collapsed segments reel out of the globules. The reeled-out segments are hydrated immediately upon exposure to water. The calculations suggest a possible shift to higher temperatures of the cloud points of aqueous PNIPAM solutions under shear flow. The reentrant coil−globule−coil transition in mixed solvent of water and methanol is studied from the viewpoint of competitive hydrogen bonds between polymer−water and polymer−methanol.
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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) | 0.000 | 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 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".