Picosecond Fluorescence Studies of the Surface Morphology of Charged Polystyrene Latex Particles
Bibliographic record
Abstract
Two negatively charged polystyrene latex dispersions with particles of similar diameter (around 100 nm) but different surface charge density (1.7 μC/cm 2 for CG18 and 2.3 μC/cm 2 for CG5) were compared in terms of their surface morphology. Since they were synthesized in the presence of a redox initiator (potassium persulfate/sodium metabisulfite), particles bore sulfate and sulfonate charged groups at the surface. Fluorescence decay measurements were performed in situ on these latex samples, using a pair of fluorescent cationic dyes adsorbed onto the surface: Rhodamine 6G (R6G) as the energy transfer donor and malachite green carbinol hydrochloride (MG) as the acceptor. Since the kinetics of the direct nonradiative energy transfer process between the dyes is sensitive to the donor and acceptor distributions, fluorescence decay measurements provide information about the binding distribution of the cationic dyes, which reflects the distribution of the negative charges at the latex particle surface. For the highly charged sample (CG5), we found a dye distribution reflecting an interface thickness with an average value of δ = 2.9 ± 0.2 nm. For the CG18 sample, having a lower surface charge density, a thinner dye distribution was evidenced, with an interface thickness δ = 2.0 ± 0.1 nm. The broadening of the distribution with the increase of surface charge density was interpreted in terms of the steric hindrance and the electrostatic repulsion between the charged polymer chain ends extending into the aqueous medium.
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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".