Long-Range, Polymer Chain Dynamics of a “Stiff” Polymer. Fluorescence from Poly(isobutylene-<i>alt</i>-maleic anhydride) with <i>N</i>-(1-Pyrenylmethyl)succinimide Groups
Bibliographic record
Abstract
The steady-state fluorescence (SSF) spectra and time-resolved fluorescence (TRF) decays of five poly(isobutylene- alt -maleic anhydride) copolymers (PIMA), randomly labeled with N- (1-pyrenylmethyl)succinimide groups (Py-PIMA), have been analyzed in order to describe their long-range, polymer chain dynamics (LRPCD) and to assess the stiffness of the PIMA backbone compared to that of a series of poly(alkyl methacrylate)s whose LRPCD had already been investigated. The SSF spectra, recorded under dilute concentration conditions where only intra chain events are important, show that the intensity ratio of pyrenyl excimer to pyrenyl monomer emission (i.e., ( I E / I M ) SSF ) increases linearly with increasing pyrenyl content as a result of increased pyrenyl–pyrenyl contacts and diffusive encounters. The slope of the straight line, m ( I E / I M ), that reflected the efficiency of pyrenyl excimer formation for Py-PIMA, was found to be 60% smaller than for even poly(octadecyl methacrylate) (PC18MA), a polymer exhibiting slow LRPCD due to its long, bulky side chain. Analyses of the SSF spectra allowed separation of the averaged behavior of five different pyrenyl species in the Py-PIMA polymers, although only two of them were reflected in the LRPCD of PIMA. In addition, the fluorescence decays of the pyrenyl monomer and excimer, when fitted globally according to the model free analysis (MFA), yielded the average rate constant ⟨ k MF ⟩ blob of pyrenyl excimer formation that directly represents the LRPCD of Py-PIMA. After having conducted two tests that confirmed the validity of the parameters retrieved from the MFA of the TRF decays, ⟨ k MF ⟩ blob for Py-PIMA was compared to ⟨ k MF ⟩ blob of nine other polymers. The result of this comparison leads us to conclude that the PIMA backbone is extremely stiff in THF. This study demonstrates the ability of the MFA of fluorescence decays acquired from polymers randomly labeled with pyrenyl groups to characterize quantitatively the LRPCD of even extremely stiff polymers.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.002 | 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 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".