Synthesis of α,ω-Dimercapto Poly(<i>N</i>-isopropylacrylamides) by RAFT Polymerization with a Hydrophilic Difunctional Chain Transfer Agent
Bibliographic record
Abstract
A new hydrophilic difunctional reversible addition−fragmentation chain transfer (RAFT) agent, diethylene glycol di(2-(1-isobutyl)sulfanylthiocarbonylsulfanyl-2-methylpropionate) (DEGDIM ) was synthesized and shown to be effective in imparting living characteristics to the radical polymerization of N -isopropylacrylamide (NIPAM), providing a route to telechelic poly( N -isopropylacrylamides) (PNIPAM) of predictable molecular weights and narrow molecular weight distributions. The thiocarbonylthio end groups were transformed into thiol groups via aminolysis with near quantitative yields, as determined by a thiol-specific quantitative UV absorbance assay. By using a pyrene-substituted initiator, bis( N -(1-pyrenylbutyl))-4,4‘-azobis-(4-cyanopentanamide) (BPAC), it was found that the amount of initiator-derived polymer chains in the DEGDIM mediated polymerization of NIPAM was negligible (∼1%) compared to the amount of polymer chains derived from DEGDIM, the difunctional chain transfer agent. These results support the theoretical calculations and confirm the high purity of α,ω-dithiol telechelic hydrosoluble polymers prepared by the RAFT polymerization process.
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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 | 0.001 |
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; 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".