Diffusion Limited Chain Transfer in Styrene Emulsion Polymerization: Use of n‐Dodecanethiol to Regulate Molecular Weight
Bibliographic record
Abstract
Low volatility chain transfer agents such as n‐dodecanethiol (n‐DDT) are important for controlling molecular weight in the production of polymers containing styrene. The high reactivity of n‐DDT towards the styrenic radical, coupled with its low solubility in the aqueous phase, often leads to conditions of diffusion limited chain transfer in which the transport rate of n‐DDT from the monomer droplets to the polymerizing particles is inadequate to maintain equilibrium concentration in the particles. The extent to which the particles are “starved” of n‐DDT has been studied by measuring n‐DDT consumption and molecular weight during styrene emulsion polymerizations. Varying surfactant and/or initiator concentration is shown to alter the n‐DDT consumption and the molecular weight profiles. The two‐film diffusion theory was applied to our data using monomer droplet and polymer particle measurements. Experimental data and theoretical considerations support the existence of monomer droplets beyond the expected end of Interval II for styrene emulsion polymerization.
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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 | 0.001 |
| 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 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".