Gas-Phase Conformations of Synthetic Polymers: Poly(ethylene glycol), Poly(propylene glycol), and Poly(tetramethylene glycol)
Bibliographic record
Abstract
Effects of chain flexibility and cationizing agent on the gas-phase conformations of a series of polyethers were studied. Collision cross-sections of poly(propylene glycol) (PPG) and poly(tetramethylene glycol) (PTMEG) oligomers (from the 5-mer to 14-mer) cationized by sodium were measured using ion mobility methods and compared to earlier work on sodiated poly(ethylene glycol) (PEG). Molecular mechanics/dynamics calculations show that all three polyethers form a ring of oxygen atoms around Na +, coordinating additional oxygens to the cation from above and/or below this ring. However, the number and arrangement of these oxygens are system dependent. Up to 8 oxygens in PEG coordinate Na +, but that number drops to 7 for PPG and 6 for PTMEG. The difference is attributed to changes in the structural details of the ring as well as the position of the Na + ion in that ring. Molecular mechanics/dynamics calculations were also used to investigate the structures of neutral PPG and PTMEG oligomers. In these cases, the oligomers are relatively compact below 200 K but they suddenly unfold into more extended structures between 200 and 300 K.
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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".