Bibliographic record
Abstract
A method for the preparation of arborescent polystyrenes based on acetyl coupling sites is described. The acetyl functionalities are randomly introduced on the grafting substrate by reacting polystyrene with acetyl chloride in the presence of anhydrous AlCl 3 in nitrobenzene. Anionic polymerization of styrene with sec -butyllithium yields polystyryllithium serving as side chains; coupling of the side chains with the acetylated substrate generates the graft polymers. Direct coupling of polystyryllithium with acetylated polystyrene suffers from a low grafting yield (∼65% for a linear substrate), due to deactivation of the macroanions by side reactions. End-capping of polystyryllithium with a few isoprene or 2-vinylpyridine units, along with the addition of LiCl, increases the grafting yield to >95%. Repetition of acetylation and anionic grafting cycles leads to generations of arborescent polymers with a low polydispersity index ( M w / M n = 1.07−1.09). The polymers are characterized by a very compact structure and by a branching functionality and molecular weight increasing geometrically for successive generations. Tailor-designed arborescent architectures are attainable by this “graft-on-graft” procedure, by controlling the acetylation level and the molecular weight of the side chains used for each grafting reaction.
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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) | 0.001 | 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 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.002 |
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".