Continuous Polymerizations in Supercritical Carbon Dioxide
Bibliographic record
Abstract
We have developed a system for the continuous polymerization of various monomers in scCO 2 and the continuous removal of polymer particles from high-pressure to ambient conditions. Experiments have been performed with the surfactant-free precipitation polymerization of vinylidene fluoride (VF2) and acrylic acid (AA) utilizing diethyl peroxydicarbonate (DEPDC) as the free-radical initiator for VF2, and 2,2'-azobis(isobutyronitrile) (AIBN) as the freeradical initiator for AA. The PVDF and AA polymers were collected as dry, "free-flowing" powders. Tunable bimodal molecular weight distributions (MWDs) of poly(vinylidene fluoride) (PVDF) were achieved by varying the VF2 concentration. The conversion of VF2 in these polymerizations ranged from 7 to 26%, and the rate of polymerization (R p ) reached a maximum of 27 x 10 -5 mol/L-s at a VF2 feed monomer concentration of 2.5 mol/L at 75 °C. Homogeneous freeradical kinetics provided a good approximation for the rate of polymerization (R p ) of this heterogeneous polymerization. The PVDF material was characterized by gel permeation chromatography (GPC) and melt flow index (MFI) giving M w 's up to 104 kg/mol, and MFI's as low as 3.0 at 230 °C.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".