<sup>13</sup>C MAS NMR Study of Poly(methacrylic acid)–Polyether Complexes and Multilayers
Bibliographic record
Abstract
Hydrogen-bonded interpolymer complexes are widely used as stimuli-responsive materials. This solid-state 13 C MAS NMR spectroscopy study examines the influence of water and temperature on the hydrogen bond structures of 13 C-labeled poly(methacrylic acid) (PMAA) complexes with poly(ethylene oxide) (PEO) and poly(vinyl methyl ether) (PVME). The spatial variation of the inter- and intrapolymer hydrogen bonds in the dried bulk complexes and supported multilayers was measured by 2D 13 C exchange (EXSY) NMR. In contrast to earlier studies of PAA complexes, the cross-peak intensities of the PMAA complexes are primarily due to 13 C spin exchange rather than H-bond exchange due to the use of 13 C-labeled PMAA and slower dynamics. The 13 C– 13 C spin diffusion between the carbonyl groups with intra- versus interpolymer hydrogen bonds indicates interatomic distances of <7 Å, consistent with interpolymer and the different intra-PMAA hydrogen bonds occurring together along the PMAA chain segments or in nanodomains in close proximity rather than isolated clusters. The fractional population involved in the spin diffusion corresponded to the population of the stronger cyclic dimer, such that PMAA–PEO complex > PVME complex > PEO supported multilayers > PVME supported multilayers. For the multilayer films, there are fewer of the stronger, more ordered cyclic dimer hydrogen bonds due to the disordering effect of the interfaces.
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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".