Fluorene-Based Poly(arylene ether sulfone)s Containing Clustered Flexible Pendant Sulfonic Acids as Proton Exchange Membranes
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Bibliographic record
Abstract
A new bisphenol monomer, 9,9-bis(3,5-dimethoxy-4-hydroxyphenyl) fluorene, was synthesized and polymerized to form fluorene-based poly(arylene ether sulfone) copolymers containing tetra-methoxy groups (MPAES). After converting the methoxy group to the reactive hydroxyl group, the respective side-chain type sulfonated copolymers (SPAES) were obtained by sulfobutylation. The polymers were characterized by 1 H NMR, thermogravimetric analysis (TGA), water uptake, and proton and methanol transport for fuel cell applications. These SPAES copolymers had good overall properties as polymer electrolyte membrane (PEM) materials, having high proton conductivity in the range of 0.061–0.209 and 0.146–0.365 S/cm at 30 and 80 °C (under hydrated conditions), respectively. SPAES-39 (IEC = 1.93 mequiv/g) showed higher or comparable proton conductivity than that of Nafion 117 at 50–95% RH (relative humidity). The methanol permeabilities of these membranes were in the range of 3.22 to 13.1 × 10 –7 cm 2 /s, which is lower than Nafion (15.5 × 10 –7 cm 2 /s). In comparison with some reported sulfonated poly(arylene ether sulfone)s containing pendent sulfophenyl groups, the present fluorene-based SPAES containing clustered flexible pendent aliphatic sulfonic acid groups displayed better properties, such as lower water uptake and higher proton conductivities. A combination of high proton conductivities, low water uptake, and low methanol permeabilities for selected SPAES indicates that they are good candidate proton exchange membrane materials for evaluation in fuel cell applications.
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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) | 0.002 | 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 it