Effects of replacing carbamate with alkyl side chains on the properties and temperature sensing performance of hemi-isoindigo-based polymers
Bibliographic record
Abstract
Abstract Previously, we developed several carbamate side chain-substituted hemi-isoindigo (HID)-based π-conjugated polymers, which demonstrated excellent sensitivity and stability as the sensing layers in chemiresistive temperature sensors. This work investigated the effects of the side chains on the HID units by changing the carbamate to alkyl side chains. Specifically, a series of 2-ethylhexyl-substituted HID polymers, poly(3-((3'',4'-bis(dodecyloxy)-[2,2':5',2''-terthiophen]-5-yl) methylene)-1-(2-ethylhexyl)indolin-2-one-6,5”-diyl) (PTAB), poly(3-((3'',4'-bis(dodecyloxy)-3,4-dimethoxy-[2,2':5',2''-terthiophen]-5-yl) methylene)-1-(2-ethylhexyl)indolin-2-one-6,5”-diyl) (PMAB), and poly(3-((7-(3,3'-bis(dodecyloxy)-[2,2'-bithiophen]-5-yl)-2,3-dihydrothieno[3,4-b] [1,4]dioxin-5-yl)methylene)-1-(2-ethylhexyl)indolin-2-one-6,5”-diyl) (PEAB) were synthesized, and their properties and temperature sensing performance were compared with their counterpart carbamate-substituted HID polymers, poly(2-ethylhexyl-3-((3'',4'-bis(dodecyloxy)-[2,2':5',2''-terthiophen]-5-yl)methylene)-2-oxoindoline-1-carboxylate-6,5”-diyl) (PTEB), poly(2-ethylhexyl-3-((3'',4'-bis(dodecyloxy)-3,4-dimethoxy-[2,2':5',2''-terthiophen]-5-yl)methylene)-2-oxoindoline-1-carboxylate-6,5”-diyl) (PMEB), and poly(2-ethylhexyl-3-((7-(3,3'-bis(dodecyloxy)-[2,2'-bithiophen]-5-yl)-2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)methylene)-2-oxoindoline-1-carboxylate-6,5”-diyl) (PEEB), and their thermally annealed products, poly(3-((3'',4'-bis(dodecyloxy)-[2,2':5',2''-terthiophen]-5-yl)methylene)indolin-2-one-6,5”-diyl) (PTNB), poly(3-((3'',4'-bis(dodecyloxy)-3,4-dimethoxy-[2,2':5',2''-terthiophen]-5-yl)methylene)indolin-2-one-6,5”-diyl) (PMNB), and poly(3-((7-(3,3'-bis(dodecyloxy)-[2,2'-bithiophen]-5-yl)-2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)methylene)indolin-2-one-6,5”-diyl) (PENB). The highest occupied molecular orbital energy (E HOMO) level and crystallinity of PEAB are very similar compared to PEEB. Chemiresistor devices with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) (PEAB:F4TCNQ) fabricated on flexible plastic substrates exhibited a high temperature coefficient of resistance (TCR) of −1.09% °C−1, although the value is lower than that (−1.92% °C−1) of the device based on PENB:F4TCNQ. The device based on PEAB:F4TCNQ also showed excellent stability with no performance degradation over 1 month, which is similar to the device based on PENB:F4TCNQ. On the other hand, PTAB and PMAB showed significantly higher E HOMO levels and crystallinity compared to their counterpart polymers. Sensors based on PTAB:F4TCNQ and PMAB:F4TCNQ showed TCR values of −1.02% °C−1 and −1.15% °C−1, respectively, which are lower than their corresponding annealed carbamate-substituted HID polymers. PTAB has a much lower E HOMO level (−4.95 eV) than that of PTNB (−4.69 eV) and is more crystalline than the latter, which should lead to poorer stability of the doped complex PTAB:F4TCNQ. Surprisingly, PTAB:F4TCNQ showed much better long-term stability than PTNB:F4TCNQ. It was considered that the hydrophobic alkyl side chains in PTAB can help prevent the interaction of water in the air with the PTAB:F4TCNQ complex, thereby stabilizing the complex. This study provided new insights into the design principles of conjugated polymers for printed and flexible temperature sensors.
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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".