Interface Thickness of a Styrene−Methyl Methacrylate Block Copolymer in the Lamella Phase by Direct Nonradiative Energy Transfer
Bibliographic record
Abstract
This paper examines the use of direct nonradiative energy transfer (DET) experiments to determine the interface thickness in films of symmetric poly(styrene- b -methyl methacrylate) (PS−PMMA) block copolymers. The films were prepared from mixtures of two polymers of identical length and compositions, labeled at their junctions with either a 9-phenanthryl or 2-anthryl group. The fluorescence decays were analyzed in terms of a model that takes account of the Helfand−Tagami distribution profile of polymer segments at the interface. Reliable data analysis required careful subtraction of a background fluorescence from the measured decay profiles. Unlike neutron reflectivity experiments, DET measurements are insensitive to capillary waves at the interface. This advantage is offset by a strong sensitivity to the characteristic distance for energy transfer R 0, which has to be determined separately. When we take R 0 = 2.3 nm, we recover an interface thickness of 4.8 nm. We obtain a theoretical value of 4.2 nm when using the Semenov's finite-chain correction to Helfand−Tagami prediction and the Flory−Huggins χ FH parameter recovered by Russell for partially deuterated d-PS−PMMA copolymer. When we employ the Callaghan and Paul χ FH value for undeuterated PS + PMMA blends, we obtain δ = 4.9 nm.
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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".