Sulfonated Poly(aryl ether ketone)s Containing the Hexafluoroisopropylidene Diphenyl Moiety Prepared by Direct Copolymerization, as Proton Exchange Membranes for Fuel Cell Application
Bibliographic record
Abstract
A series of sulfonated poly(aryl ether ketone) (SPAEK-6F) copolymers were prepared by aromatic nucleophilic polycondensation of hexafluoroisopropylidene diphenol with 5,5‘-carbonylbis(2-fluorobenzenesulfonate) and 4,4‘-difluorobenzophenone (DFBP) at various molar ratios. The synthesized SPAEK-6F polymers possessed high molecular weights revealed by their high viscosity, and tough and flexible membranes were obtained by casting from DMAc solution. The sulfonate or sulfonic acid content (SC) of the polymers, expressed as a number per repeat unit of polymer, was determined by 1 H NMR spectroscopy and was in good agreement with the initial monomer ratios. The membranes exhibited increased water uptake and swelling with increasing SC and temperature. SPAEK-6F membranes with SC ranging from 0.6 to 1.14 maintained adequate mechanical strength after immersion in water at 80 °C for 24 h. Fenton's reagent test revealed that the SPAEK-6F membranes had good stability to oxidation. The proton conductivities of the SPAEK-6F films increased with SC and temperature, reaching values above 3 × 10 -2 S/cm at 80 °C for SC ≥ 0.75. The tensile test indicated that the SPAEK-6F membranes with SC 0.75, 0.98, and 1.14 are tough and strong at ambient conditions. Consequently, these materials proved to be promising as proton exchange membranes and may be potentially useful for application in fuel cells operated at medium temperatures.
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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".