Arborescent polystyrene-graft-poly(2-vinylpyridine) copolymers: solution polyelectrolyte behavior
Bibliographic record
Abstract
Branched polyelectrolyte precursors were obtained on a 100 g scale by coupling ‘living’ poly(2-vinylpyridine) (P2VP) macroanions with linear polystyrene and arborescent polystyrene substrates of generations G0 or G1, functionalized with acetyl groups. Arborescent copolymers with Mn ≈ 5000 or 30 000 side-chains and containing 87–98 mol% of P2VP were thus synthesized. These materials are characterized by a very compact structure, a narrow molecular weight distribution (Mw/Mn = 1.08–1.10), and a roughly geometric increase in branching functionality and molecular weight for successive generations. The copolymers are freely soluble in water and in polar organic solvents such as methanol and N,N-dimethylformamide (DMF) upon protonation by trifluoroacetic acid (TFA), a strong acid. The solutions obtained display properties typical of polyelectrolytes, including strong curvature in plots of reduced viscosity (ηsp/C) versus concentration (C) at low concentrations. The copolymers exhibit larger reduced viscosity increases in methanol than in DMF, and coil expansion apparently varies in the order G1 > G0 > G2. The reduced viscosity of the arborescent polyelectrolyte solutions is much lower than for linear P2VP samples of comparable molecular weights, however, due to the small dimensions and increased structural rigidity of the molecules. The addition of salts to the branched polyelectrolyte solutions further decreases their viscosity and the curvature of the reduced viscosity plots, presumably as a result of charge screening.
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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".