Molar Mass Effect on the Rate of Polymer Diffusion in Poly(vinyl acetate-<i>co</i>-butyl acrylate) Latex Films
Bibliographic record
Abstract
The effect of molar mass and gel content on the rate of polymer diffusion in film based on poly(vinyl acetate- co -butyl acrylate) P(VAc-BA) latex particles with a 4:1 weight ratio of VAc and BA is examined by fluorescence decay measurements of nonradiative energy transfer (ET). P(VAc-BA) latex particles labeled with phenanthrene (Phe) as the donor and with 4‘-(dimethylamino)benzophenone (NBen) as the acceptor were prepared by semicontinuous emulsion polymerization in the presence of different amounts of chain transfer agent to modify the mean molar mass and gel content of the latex particles. We synthesized three sets of samples, which we refer to as high M, medium M, and low M . The high M sample had about 40% gel content, and the sol fraction extracted from the polymer had a nominal M w (GPC) of 125 000. The medium M and low M samples had a negligible gel content and corresponding values of M w ≈ 75 000 and 42 000, with a broad size distribution. The rate of polymer diffusion in these films was found to increase strongly with decreasing mean molar mass. The diffusion rate increased with annealing temperature. For the high M sample, we found that the diffusion rate was characterized by an apparent activation energy E a = 37 kcal/mol. This value is somewhat larger than that ( E a = 34 kcal/mol) reported previously for the medium M sample determined both by ET experiments and by viscoelastic relaxation measurements. The extent of mixing parameter f m showed a power law dependence on diffusion time, with f m ∼ t z, with z values on the order of 0.12−0.18.
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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) | 0.001 | 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 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".