Synthesis and Solubility of Linear Poly(tetrafluoroethylene-<i>co</i>-vinyl acetate) in Dense CO<sub>2</sub>: Experimental and Molecular Modeling Results
Bibliographic record
Abstract
Supercritical carbon dioxide was used as a reaction medium to synthesize statistically random (i.e., no specific correlation between the location of the monomers on the polymer) copolymers of tetrafluoroethylene (TFE) and vinyl acetate (VAc) with similar molar mass and 11.6−63.3 mol % TFE content. The solubility of the copolymers at 25 °C in CO 2 reduced after reaching a maximum value at a TFE molar concentration of 19.3 mol %. The 46.7 mol % TFE copolymer only dissolved in CO 2 at elevated temperatures, whereas the 63.3 mol % TFE copolymer did not dissolve in CO 2 even at temperatures in excess of 144 °C and pressures of 210 MPa. The molecular modeling results show that the interaction of CO 2 with acetate side group was not affected by presence of fluorine in the polymer backbone; therefore, the enhanced solubility of the semifluorinated copolymers is attributable to the enhanced binding between CO 2 and the semifluorinated backbone of the copolymer when the CO 2 molecule can access both the fluorinated (Lewis base) and hydrogenated (Lewis acid) parts of the backbone simultaneously.
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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".