Hydrophobic and Elastic Forces Experienced by a Series of Pyrene End-Labeled Poly(ethylene oxide)s Interacting with Sodium Dodecyl Sulfate Micelles
Bibliographic record
Abstract
A series of pyrene end-labeled poly(ethylene oxide)s (Py 2 -PEO( x ) with x equal to 2, 3.4, 5, 6, 7.8, and 10 kg mol –1 ) were synthesized, and their interactions with SDS micelles were characterized by steady-state and time-resolved fluorescence. Pyrene excimer formation (PEF) indicated that both pyrenyl ends were located in the same SDS micelle whereas the absence of PEF reflected bridging of two SDS micelles by a Py 2 -PEO molecule having its pyrenyl end groups in separate micelles. PEF efficiency was characterized from the excimer-to-monomer fluorescence intensity ratio ( I E / I M ) which was determined as a function of PEO chain length and salt concentration. More detailed information about the PEF process was obtained by fitting the monomer and excimer fluorescence decays globally according to the model free analysis (MFA). MFA yielded the average rate constant ⟨ k ⟩ of PEF and the molar fraction ( f free ) of pyrenyl labels that did not form excimer, thus reflecting the extent of bridging undergone by the Py 2 -PEO constructs. Bridging was inferred for the two longest Py 2 -PEO constructs but not for the shorter Py 2 -PEO(2K) sample, since f free was large and small for the former and latter constructs, respectively. The most interesting behavior was observed for Py 2 -PEO(6K) where a substantial increase in f free was detected upon addition of a minute amount of NaCl. The Py 2 -PEO(6K) construct marked the boundary between the regimes where bridging would or would not occur with or without salt, respectively. This observation led to a quantitative analysis of the energies involved in restraining the two end groups of a Py 2 -PEO construct in the same SDS micelle and in extending a PEO chain to bridge two SDS micelles occupied by one pyrenyl end of a Py 2 -PEO construct. The theoretical energy calculations were found to predict fairly accurately the f free trends obtained experimentally by the MFA of the Py 2 -PEO fluorescence decays.
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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".