Pressure- and Temperature-Induced Association of Arborescent Polystyrene-<i>graft</i>-poly(ethylene oxide) Copolymers at the Air−Water Interface
Bibliographic record
Abstract
The influence of surface pressure and subphase temperature on the association of arborescent polystyrene- graft-poly(ethylene oxide) (PS- g-PEO) copolymers at the air-water interface was investigated using the Langmuir balance and atomic force microscopy (AFM) techniques. These dendritic molecules form stable condensed monolayers with surface compressional moduli >250 mN/m. The variation in film thickness observed as a function of surface pressure suggests that at low surface pressures (gaslike phase) the PEO chains remain adsorbed at the air-water interface. At higher surface pressures (condensed phase), the PEO chains partially desorb into the subphase and adopt a more brushlike conformation. Large islandlike clusters with a broad size distribution were observed for samples with PEO contents of up to 15% by weight. In contrast, copolymers with PEO contents of 22-43% displayed enhanced side-by-side association into ribbonlike superstructures upon compression. The same effect was observed even in the absence of compression when the subphase temperature was increased from 12 to 27 degrees C. The temperature-induced association was attributed to increased van der Waals attractive forces between the PS cores relative to the steric repulsive forces between PEO chains in the coronas because the solvent quality for the PEO segments decreased at higher temperatures. The restricted number of superstructures observed for arborescent copolymers as compared with linear- and star-branched PS-PEO block copolymers is attributed to the enhanced structural rigidity of the molecules due to branching.
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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".