Tailoring the morphology in partially and fully miscible mixtures of PEEK and PEI
Bibliographic record
Abstract
Over the last three decades, the vast body of work related to the control of the morphology of multiphase polymers has concentrated on systems that are inherently immiscible. On the other hand, detailed morphological studies of phase separation in miscible blends have been limited by the highly unstable nature of the structures generated as a function of time and temperature. In this work, we present one basic polymer system, with a slight variation in chemical structure, that allows for a high level of morphological tailoring and control in the miscible to partially miscible region. Two close isomeric forms of polyetherimides (PEI) yield fundamentally different types of morphologies in polyetheretherketone (PEEK)/PEI melt-processed multiphase systems: a partially miscible, phase-separated microstructure for the barely studied PEEK/ para -PEI ( p -PEI) system, and the typically reported fully miscible PEEK/ meta -PEI system ( m -PEI). The PEEK/ p -PEI system displays sub-μm, matrix/dispersed phase or co-continuous types of morphologies, with the latter quickly coarsening over tens of μm in length scale under quiescent annealing conditions due to the PEEK/ p -PEI interfacial tension, which was measured by the breaking thread method at 0.14 mN/m, one of the lowest values ever reported for a polymer pair. On the other hand, for the PEEK/ m -PEI system, controlling the thermal annealing temperature promotes PEEK recrystallization and the formation of a nanostructured PEI-rich phase. Considering both types of blends, it is then possible to control the morphological length scale of PEEK and PEI domains over nearly 4 orders of magnitude, from ≈5 nm to over 15 μm. This is the smallest domain size ever reported for co-continuous systems. The selective extraction of the PEI phase then results in porous PEEK monoliths with full pore interconnectivity, with an average pore size spanning the same considerable range – without any interfacial modifier or block copolymer. • PEEK/ para -PEI displays partial miscibility, compared to full miscibility for PEEK/ meta -PEI. • PEEK/ para -PEI has a very low interfacial tension (0.14 mN/m), amongst the lowest reported. • PEEK/ para -PEI can display a fine co-continuous morphology (≈0.3 μm), coarsening upon annealing. • Porous PEEK with tunable pore size (5 nm–15 μm) are obtained without interfacial modifiers.
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How this classification was reachedexpand
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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".