Homogeneous and Segmented Nanofibers with a Conjugated Poly[3-(2′-ethylhexyl)thiophene] Core via Living Crystallization-Driven Self-Assembly
Bibliographic record
Abstract
The ambient temperature living crystallization-driven self-assembly (CDSA) seeded growth method for polymeric amphiphiles with a crystallizable core-forming block has emerged as a promising approach to morphologically pure samples of uniform, length-controlled one-dimensional nanofibers as well as more complex architectures such as segmented assemblies. Access to nanofibers with poly(3-hexylthiophene) (P3HT) as the core-forming block is highly desirable as a result of their optoelectronic properties. However, application of the living CDSA method to P3HT diblock copolymers has proven to be a challenge due to rapid P3HT crystallization. This causes uncontrolled homogeneous nucleation and defect formation, resulting in a loss of length control and increased nanofiber length dispersity. Herein, we have explored the replacement of the P3HT core-forming block with a more soluble poly[3-(2′-ethylhexyl)thiophene] (P3EHT) core and demonstrate improved control over nanofiber formation. Specifically, we have studied two P3EHT-containing diblock copolymers, P3EHT 23 - b -PEG 113 [PEG = poly(ethylene glycol)] and P3EHT 19 - b -P2VP 138 [P2VP = poly(2-vinylpyridine)]. Seeded growth of P3EHT 19 - b -P2VP 138 nanofibers at 22 °C produced low dispersity nanofibers with length control up to ∼1 μm, while P3EHT 23 - b -PEG 113 only provided length control up to ∼300 nm under similar conditions. Self-nucleation was postulated to impair efficient seeded growth of P3EHT 23 - b -PEG 113 and solution-state variable temperature UV–vis spectroscopy was used to locate temperatures where self-nucleation was suppressed. These studies revealed that homogeneous nucleation is suppressed for at least 24 h at or above 30 °C for P3EHT 23 - b -PEG 113 in a 1:1 n -butanol:methanol solution. In the case of P3EHT 23 - b -PEG 113, this allowed us to efficiently perform seeded growth under conditions (≥30 °C) that resulted in the formation of near-uniform nanofibers with controlled lengths of up to ∼1 μm. Self-nucleation suppression was also successfully utilized during thermal self-seeding experiments, wherein P3EHT 23 - b -PEG 113 nanofibers with controlled lengths up to 2.8 μm and low length dispersities were formed. Seeded growth of P3EHT 19 - b -P2VP 138 from the termini of P3EHT 23 - b -PEG 113 seeds at 22 °C provided access to well-defined B-A-B triblock comicelles with a segmented coronal structure.
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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) | 0.000 | 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 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".