The effects of counter anions on the dynamic mechanical response in polymer networks crosslinked by metal–ligand coordination
Bibliographic record
Abstract
ABSTRACT Metal–ligand coordination has been proven to be an attractive strategy to tune a polymer network's dynamic mechanical properties, such as self‐healing ability. Nonetheless, the role of counter anions is often overlooked. To address this, a series of polydimethylsiloxane (PDMS) films crosslinked through lanthanide metal cations (Eu 3+ , Tb 3+ )–bipyridine interactions have been prepared and studied. Neutral 2,2'‐bipyridine ligands were embedded into the linear polydimethylsiloxane (PDMS) chain through polycondensation. With nitrate ( ) as the coordinating anions, metal salts Eu(NO 3 ) 3 and Tb(NO 3 ) 3 were found to be ineffective crosslinkers. With noncoordinating anions, such as triflate (OTf ‐ : CF 3 ), metal salts Eu(OTf) 3 and Tb(OTf) 3 showed improved interaction strength with bipyridine ligands. Surprisingly, the addition of Eu(OTf) 3 and Tb(OTf) 3 salts also increased the d‐spacing distances of the phase‐segregated domains between metal–ligand complexes and the PDMS polymer backbone. For the Eu(OTf) 3 ‐, Tb(OTf) 3 ‐PDMS films, the much‐improved self‐healing abilities are attributed to the crosslinker dynamics and the enhanced chain mobility. This work underlines the importance of counter anions on the mechanical properties, and provides further guidance on the future design of self‐healing metal−ligand crosslinked polymers.) © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3110–3116
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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 | 0.004 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.003 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".