Large Scale Crystallinity in Kinetically Stable Polythiophene-Based Langmuir−Blodgett Films
Bibliographic record
Abstract
The first direct observation of large scale molecular level ordering in a complex poly(3-alkylthiophene)-based thin film is reported. The fabrication and characterization of highly ordered thin films made from the regioregular, amphiphilic polythiophene derivative poly(3-(11-(2-tetrahydropyranyloxy)undecyl)thiophene) (PTHPUDT) are described. PTHPUDT affords kinetically stable, high optical quality films deposited layer-by-layer using the Langmuir-Blodgett (LB) method. X-ray diffraction studies confirm the deposition of a film with long-range order normal to the surface, characterized by bilayer separations of approximately 30 A. The films display in-plane anisotropy, associated with the preferential alignment of the polymer main chain in the dipping direction. Molecular resolution atomic force microscopy shows the presence of highly ordered crystalline domains within the plane, consistent with an ordered array of parallel, closed-packed, polythiophene chains. Polarized optical microscopy confirms the formation of large scale domains that display uniform optical retardation across macroscopic length scales. FeCl(3)-doped films yield anisotropic conduction behavior, suggesting higher rates of transport perpendicular to the main chain direction. The kinetic stability of these films is distinct from films of other polythiophenes, other deposition methods, and simpler amphiphiles, all of which tend toward their bulk, thermodynamically stable structures. This stability and long-range order are attributed to the amphiphilic nature of the polymer and the dimensional restrictions of the polymer's main chain, which limits the extent of structural defect-based reorganization, and the limited number of local structures of the alkyl chains. The degree and nature of the ordering in these semicrystalline films make them an ideal model system in which to elucidate the connection between morphology and physical property in complex pi-conjugated polymers.
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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".