Reactivity of Polyolefins toward Cumyloxy Radical: Yields and Regioselectivity of Hydrogen Atom Transfer
Bibliographic record
Abstract
Hydrogen atom abstraction from a series of homopolymers by cumyloxy radicals is examined under solvent-free conditions at temperatures that are relevant to radical-mediated polymer modifications. Abstraction efficiency data acquired for the thermolysis of dicumyl peroxide (DCP) within pure polymer samples establish an order of reactivity: poly(butadiene) (PBD) > poly(ethylene oxide) (PEO) > poly(ethylene) (PE) > poly(propylene) (PP) > poly(isobutylene) (PIB). The regioselectivity of hydrogen transfer from PE, PP, and PIB is assessed by model hydrocarbon experiments involving nitroxyl trapping of the alkyl radicals generated from pentane, 2,4-dimethylpentane, and 2,2,4,4-tetramethylpentane, respectively. Taken together, abstraction efficiency and regioselectivity data are discussed in terms of enthalpic and entropic contributions to H atom transfer rates, with particular emphasis on steric hindrance imposed by methyl substituents on secondary positions within PP and PIB. The utility of polymer oxidizability as a predictive measure of the reactivity of a polymer toward cumyloxyl and vinyltriethoxysilane graft modification is evaluated and discussed.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 teacher head, 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".