Heat-Induced Phase Transition and Crystallization of Hydrophobically End-Capped Poly(2-isopropyl-2-oxazoline)s in Water
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Bibliographic record
Abstract
The phase diagrams of semitelechelic and telechelic hydrophobically modified poly(2-isopropyl-2-oxazolines) (HM-PiPrOx) in water were characterized in terms of an extensive set of parameters: the cloud point ( T cp ), obtained from turbidity measurements, the transition temperature ( T M ) and enthalpy (Δ H ), derived from high-sensitivity differential scanning calorimetry (HS-DSC), the coefficient of thermal volume expansion, α, measured by pressure perturbation calorimetry (PPC), together with assessment by X-ray diffraction of the extent of polymer crystallization from hot water. Data were recorded as a function of the molecular weight of the polymers (7000, 10 000, and 13 000 g mol −1 ), the end-group functionality (α- n -octadecyl-ω-hydroxyl- or α,ω-di- n -octadecyl-), the polymer concentration (0.1−10 g L −1 ), and the solvent (H 2 O or D 2 O). For all polymer solutions, the cloud point temperature was lower than the transition temperature, in agreement with previous studies of telechelic HM-poly(ethylene oxides) and HM-poly( N -isopropylacrylamides) aqueous solutions. In solutions of all telechelic HM-PiPrOx and of the semitelechelic HM-PiPrOx 7000 and 10 000 g mol −1, the onset of turbidity was accompanied by an endotherm attributed to a rigid-to-fluid phase transition of the hydrophobic core of the polymeric micelles formed in aqueous solutions kept below T cp . Semitelechelic HM-PiPrOx samples crystallized from water upon prolonged heating at 70 °C, whereas telechelic HM-PiPrOx samples remained amorphous under these conditions. The results are discussed in terms of the dipole−dipole interactions between adjacent PiPrOx chains in the micelle corona which restrict the motion of n -octadecyl chains in the micellar core and favor intermicellar interactions. Water molecules acting as hydrogen-bound cross-linker between polymer chains also contribute to intra- and intermicellar PiPrOx chain association.
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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 | 0.000 | 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) | 0.000 | 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 it