End Group Effect on the Thermal Response of Narrow-Disperse Poly(<i>N</i>-isopropylacrylamide) Prepared by Atom Transfer Radical Polymerization
Bibliographic record
Abstract
Four series of narrow-disperse poly( N -isopropylacrylamide) (PNIPAM) with well-controlled molecular weights and with end groups of varying hydrophobicity were synthesized by room temperature atom transfer radical polymerization in 2-propanol using the corresponding chloropropionate and chloropropionamide initiators. The thermal phase transitions of aqueous solutions of these PNIPAMs were studied by turbidimetry and high-sensitivity differential scanning calorimetry (HS-DSC) and showed an inverse molecular weight (MW) dependence of their cloud points. The magnitude of the MW dependence decreases when using more hydrophobic end groups. The choice of end group further affected the shape of the cloud point curves and the enthalpy of the phase transition. Above the cloud point, narrow-disperse PNIPAM sedimented more rapidly than polydisperse PNIPAM produced by conventional free radical polymerization, especially at concentrations above 1%. Thus, multiple HS-DSC scans of PNIPAM prepared by ATRP typically gave repeatable results only at lower concentrations.
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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 | 0.000 |
| 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".