PDMS–Fluorous Polyoxetane–PDMS Triblock Hybrid Elastomers: Tough and Transparent with Novel Bulk Morphologies
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Bibliographic record
Abstract
PDMS-3F-1.1-PDMS and PDMS-3F-4.5-PDMS triblock hybrid elastomers are investigated, wherein (1) 3F-1.1 and 3F-4.5 are poly(3-methyl-3-trifluoroethoxymethyl)-1,3-propylene oxide with M n = 1.1 or 4.5 kDa, (2) segments are linked by urethane/urea forming reactions, and (3) the intermediate PDMS-3F-PDMS aminopropyl end segments are end-capped with isocyanatopropyltriethoxysilane. After condensation cure, PDMS-3F-PDMS triblock hybrids (A-1.1 and A-4.5) form robust elastomers. In a second set, bis(triethoxysilylethane), BTESE, was incorporated to probe effects of increased siliceous domain content (B-1.1, B-4.5). All compositions are optically transparent due to nearly identical refractive indexes for 3F and PDMS segments. TM-AFM images for A-4.5, A-1.1, and B-4.5 fracture surfaces reveal microscale bulk phase separation. The A-4.5 triblock hybrid shows a particularly interesting morphology comprised of 2–3 μm ovaloids (low modulus) surrounded by a higher modulus matrix. A model is proposed for this microscale morphology based on the relative rates of physical network formation (PN, H-bonding) and chemical network formation (CN, SiO 1.5 ) during coating deposition Despite low hard segment weight percents (2.6–3.5) the hybrid triblocks have moderate toughness with strain at break ranging from 260 to 492%. Triblock hybrid elastomer B-1.1 has the highest −SiO 1.5 wt % (mostly from BTESE) and lowest 3F wt % (3F-1.1). No sign of microscale phase separation is observed by TM-AFM imaging, and a separate T g for the 3F segment is not detected by DMA; these findings are ascribed to network constrained phase separation of that results in 3F being incorporated in an “interphase”. The absence of a separate T g for 3F leads to a gradual decrease in storage modulus (8 to 1.4 MPa) from −90 to 150 °C. In contrast to the complex bulk morphology, TM-AFM imaging shows the hybrid surfaces are devoid of microstructural features attributable to phase separation. Based on contact angle measurements and XPS analysis, the outermost surface for all PDMS-3F-PDMS hybrid triblocks elastomers is dominated by PDMS.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 it