Nanostructure, Morphology, and Properties of Fluorous Copolymers Bearing Ionic Grafts
Bibliographic record
Abstract
In order to probe the effects of polymer microstructure on the properties of proton conducting polymer membranes, three series of fluorous−ionic graft copolymers, partially sulfonated poly([vinylidene difluoride- co -chlorotrifluoroethylene]- g -styrene) [P(VDF- co -CTFE)- g -SPS], comprising controlled graft lengths and degrees of sulfonation were synthesized. The parent building block was a poly(vinylidene difluoride- co -chlorotrifluoroethylene) [P(VDF- co -CTFE)] macroinitiator ( M n = 3.12 × 10 5 g/mol) synthesized to contain 1 chloro group per 17 repeat units, onto which polystyrene, having degrees of polymerization of 35, 88, and 154 units per graft, was grown by atom transfer radical polymerization (ATRP). These graft copolymers, termed short, medium, and long graft chains, were sulfonated to different extents to provide a series of polymers with varying ion exchange capacity (IEC). The resulting P(VDF- co -CTFE)- g -SPS copolymers were cast into proton exchange membranes, and their nanostructure, morphology, and properties were studied. TEM revealed that all three membrane series exhibit a disordered phase-separated morphology comprised of small interconnected ionic clusters varying from 2 to 4 nm in size. For a given IEC, membranes prepared from the short graft chain series possessed larger ionic domains due to their relatively higher degree of sulfonation (DS), which facilitates ion clustering. For short graft membranes, water contents and conductivities were less influenced by IEC. For high IEC membranes, ∼2.50 mmol/g, the short grafts remained water-insoluble, absorbed less water, and afforded higher conductivity than longer graft analogues. These results demonstrate the importance of polymer microstructure on the morphology of membranes, the size of ionic clusters and their ionic purity, and the microstructure’s role in water sorption and proton conductivity. From a technological viewpoint, it indicates that short ionic graft polymers enhance the elastic forces in the matrix and inhibit excessive swelling, allowing high IEC vinylic polymers to remain insoluble. As such, these architectures warrant further investigation as they reduce swelling and promote proton transport under reduced lambda values.
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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) | 0.000 | 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 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".