Influence of Single versus Double Hydrogen-Bonding Motif on the Crystallization and Morphology of Self-Assembling Carbamates with Alkyl Side Chains: Model System for Polyurethanes
Bibliographic record
Abstract
The difference in the morphology and crystallization aspects of hydrogen-bond-mediated self-assembling systems with single and double hydrogen-bonding motifs is studied here with carbamates as an example. These carbamates have alkyl side chains of various lengths, from C(4) to C(18). The biscarbamates with double hydrogen-bonding sites and symmetric substitution of alkyl segments show a significantly different morphological behavior as compared to the N-octadecyl carbamate alkyl esters (ref 5, referred to as simple carbamates henceforth) with a single hydrogen-bond motif and asymmetric substitution of alkyl side chains. In contrast to the simple carbamates in which no significant difference was found in the spherulite size from C(4) to C(12), with the biscarbamates we find that the spherulitic size, rate of growth of spherulites, and rate of crystallization show a maximum with an alkyl chain length of C(8). This is rationalized in terms of the relative contributions of the hydrogen-bond and van der Waals interaction energies. Oriented X-ray diffraction patterns from the fibrils of the spherulites lead to a model for the growth patterns of the hydrogen-bond planes and the molecular orientation in the spherulites.
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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) | 0.000 | 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 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".