Periodic Mesoporous Organosilicas with Phenylene Bridging Groups, 1,4-(CH<sub>2</sub>)<i><sub>n</sub></i>C<sub>6</sub>H<sub>4</sub> (<i>n</i> = 0−2)
Bibliographic record
Abstract
Periodic mesoporous organosilicas (PMOs) were prepared by polymerizing phenylene-bridged silsesquioxane precursors containing an incremental increase in methylene spacers [1,4-(CH 2 ) n C 6 H 4 ( n = 0−2)] in combination with polyoxyethylene(10) cetyl ether (Brij 56) oligomers as structure-directing species under acid catalysis. Surfactant templates were removed from the nanoporous inorganic−organic hybrids using acidified ethanol extractions. Mesoporous organosilicas were characterized by powder X-ray diffraction, nitrogen gas sorption, 13 C and 29 Si solid-state NMR, scanning and transmission electron microscopy, and thermogravimetric analysis. Organosilica materials formed uniform arrays of 2D-hexagonal mesopores with pore diameters ranging from 2 to 3 nm and corresponding surface areas of 750−1200 m 2 g - 1 . Addition of two methylene groups to the phenylene bridge resulted in a substantial decrease in the pore size, surface area, and pore volume. The thermal stability of the materials decreases in the following order: phenylene > 4-benzyl > p -xylene. Aryl−silicon bonded networks display greater thermal stability than methylene−silica covalently bound frameworks. Decomposition of aryl−silica units occurred between 450 and 750 °C, whereas methylene−silica moieties decomposed in the range 300−600 °C. These hybrid mesoporous materials represent the first introduction of precursors with two-structural organic-bridging units as an integral part of the organosilicate-bonded matrix.
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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 | 0.003 | 0.001 |
| Meta-epidemiology (narrow) | 0.003 | 0.003 |
| Meta-epidemiology (broad) | 0.004 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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; both teacher heads agree on what is shown here.
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".