Effect of Hexafluoro-2-propanol Substituents in Polymers on Gas Permeability and Fractional Free Volume
Bibliographic record
Abstract
A series of polymers were synthesized containing hexafluoro-2-propanol (HFP) pendant groups by facile reaction of lithiated polymers with hexafluoroacetone (HFA). The purpose of the study was to evaluate the effect of the HFP group in potential membrane gas separation materials. Dibromobisphenol A polysulfone (PSf-Br 2 ), tetramethylbisphenol A polysulfone (TMPSf), dibromohexafluorobisphenol A polysulfone (6FPSf-Br 2 ), tetramethylhexafluorobisphenol A polysulfone (TM6FPSf), and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) were modified by using n -butyllithium to form lithiated intermediates and then treated with HFA to form the corresponding modified polymers PSf-HFP, TMPSf-HFP, 6FPSf-HFP, TM6FPSf-HFP, and PPO-HFP. Polymers with various degree of substitution per repeat unit of HFP were obtained, depending upon the extent of polymer lithiation and reactivity. PSf-HFP, TM6FPSf-HFP, and PPO-HFP were further derivatized at the hydroxyl group using iodomethane to obtain the respective methylated derivatives (HFM). The polymer structures were characterized by NMR spectroscopy, and thermal properties were investigated by differential scanning calorimetry and thermogravimetric analysis. The gas permeability coefficients of these polymers were measured for the gases He, O 2, CO 2, and N 2 . The gas transport properties of PSf-HFP, PSf-HFM, and TMPSf-HFP for He/N 2, He/CO 2, O 2 /N 2, and CO 2 /N 2 gas pairs were all improved in comparison with PSf and TMPSf. The permeabilities for all gases increased 2−3-fold, while the permselectivities of the four gas pairs increased as well. All the HFP derivatives showed improvements of this magnitude only for the He/CO 2 gas pair.
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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".