Solution Properties of Hydrophobically Modified Copolymers of <i>N</i>-Isopropylacrylamide and <i>N</i>-Glycine Acrylamide: A Study by Microcalorimetry and Fluorescence Spectroscopy
Bibliographic record
Abstract
The temperature- and pH-induced coil−globule transition has been studied in dilute aqueous solutions for different copolymers of N -isopropylacrylamide (NIPAM) and N -glycine acrylamide (Gly) using turbidimetry, scanning microcalorimetry, fluorescence spectroscopy, and dynamic light scattering. The four different samples prepared are a copolymer of NIPAM and Gly (PNIPAM−Gly), a copolymer of NIPAM, Gly, and N -(1-pyrenyl)methylacrylamide (PNIPAM−Gly−Py), and their hydrophobically modified (HM) derivatives, namely a copolymer of NIPAM, Gly, and N -( n -octadecylacrylamide) (PNIPAM−Gly−C 18 ) and a copolymer of NIPAM, Gly, and N -[4-(1-pyrenyl)butyl]- N - n -octadecylacrylamide (PNIPAM−Gly−C 18 Py). Polymeric micelles 16 ± 2 nm in diameter were detected in cold solutions of the hydrophobically modified polymers. All polymers underwent pH-dependent phase separation upon heating. Endotherms with enthalpies on the order of the strength of hydrogen bonds were observed at temperatures concurring, in the case of PNIPAM−Gly and PNIPAM−Gly−Py, with the transition temperatures detected by classical cloud-point measurements. Discrepancies between the two values were detected in the case of the hydrophobically modified polymers. Evidence from fluorescence spectroscopy, corroborated by dynamic light scattering and microcalorimetry data, suggests that the pH- or temperature-stimulated coil to globule collapse of the polymer main chain does not trigger the disruption of the hydrophobic core of HM-polymer micelles.
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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".