Persistence Length of Poly( <i>n</i> -butyl methacrylate- <i>co</i> - <i>n</i> -stearyl methacrylate)s Determined by Pyrene Excimer Formation
Bibliographic record
Abstract
A series of poly( n -butyl methacrylate- co -stearyl methacrylate) copolymers randomly labeled with 1-pyrenebutanol and referred to as PyC 4 –P(C 4 MA- co -C 18 MA) were synthesized by free radical copolymerization of 1-pyrenebutyl methacrylate, n -butyl methacrylate, and stearyl methacrylate. Their persistence length ( l p ) was determined experimentally by pyrene excimer formation (PEF) between an excited and a ground-state pyrenyl label attached to the copolymers to validate theoretical predictions relating l p to the molar fraction of the comonomers in the copolymer. To this end, the chemical composition of the copolymers was characterized by a combination of 1 H NMR and UV–vis spectrophotometry and their molecular weight distribution was determined by gel permeation chromatography. The fluorescence decays of the pyrene monomer and excimer were acquired for the copolymers in o -xylene and fitted globally according to the fluorescence blob model (FBM) to determine the number ( N blob ) of structural units inside a blob representing the volume probed by an excited pyrenyl label. N blob decreased with increasing molar fraction ( x 18 ) of stearyl methacrylate in the PyC 4 –P(C 4 MA- co -C 18 MA) copolymers reflecting the extension of the main chain induced by increased steric hindrance between the longer stearyl side chains. The N blob values obtained for the PyC 4 –P(C 4 MA- co -C 18 MA) copolymers were then used to determine their l p based on a modified Kratky–Porod equation. l p increased linearly as x C18 17/8, as predicted theoretically. The l p determined for the copolymers matched those obtained by PEF and viscometry for other methacrylate homopolymers with a side chain length matching the number-average side chain length of the copolymers. The agreement between theory and experiments validates the theoretical predictions for determining l p and PEF for characterizing macromolecular conformations.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 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".