Real-Time Mid-IR Monitoring of the Initiation and Propagation in Epoxi-Initiated Living Isobutylene Polymerizations
Bibliographic record
Abstract
The initiation and propagation of isobutylene (IB) polymerization initiated by 1,2-epoxi-2,4,4-trimethylpentane (TMPO-1)/TiCl 4 was monitored by a new fiber-optic transmission mid-IR probe. The real-time IR data provided insight into the initiation mechanism. Polyether formation, isomerization of the TMPO-1 into 2,4,4-trimethylpentanal, and its complexation by TiCl 4 were observed, which occurred simultaneously with initiation of IB polymerization. The proposed initiating mechanism involves the formation of tertiary carbocations, which has been claimed to occur in the cationic polymerization of epoxides by the S N 1 mechanism. On the basis of our results, the competitive occurrence of both S N 1 and S N 2 pathways is proposed. Interestingly, ketone/TiCl 4 systems were found to initiate IB polymerization, albeit with very low efficiency. IR monitoring of these systems gave additional insight into the initiating mechanism. IB polymerization was monitored by following the disappearance of the second overtone of the C−H wag in the CH 2 group in IB at 1780 cm -1 and the C C stretch at 1655 cm -1 . The linearity of first-order monomer consumption plots and the production of nearly uniform polyisobutylenes (PIBs) ( M w / M n = 1.06−1.13) indicated living conditions.
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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 | 0.001 |
| 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".