New insights concerning the mechanism of reversible thermochromic mixtures
Bibliographic record
Abstract
Three-component organic thermochromic materials, consisting of a leuco dye, a weak acid acting as the colour developer, and a low-melting organic solvent, can change their colour in response to temperature changes. Although widely used in applications, their detailed thermochromic mechanism is not fully understood. The present study delineates the role of subtle changes in the solvent’s molecular structure and concentration in the crystal violet lactone (CVL, dye)/lauryl gallate (LG, developer)/1-alcohol (dodecanol (DD), tetradecanol (TD), hexadecanol (HD), or octadecanol (OD); solvent) system. Through inkjet printing of the components directly onto a substrate, combinatorial approaches reveal differences when the alkyl chain length of the alcohol solvent is changed slightly. During the process of heating to the melt, followed by cooling to room temperature, CVL/LG/DD showed no colour change. On the other hand, CVL/LG/TD exhibited reversible thermochromism with colour forming in the molten state and colour loss in the solid state. In the composition range investigated, the CVL/LG/HD system showed no colour change during heating, but on cooling from the molten state, at first a blue colour appeared just below the freezing point, and this was followed by a slow colour fading on further cooling. A significant new finding is that the orientationally disordered α-phase of the solvent is required to support the dye–developer complex that provides colour. Furthermore, there is an optimal solvent chain length for thermochromism: if too short, there is no disordered phase and no colour; if too long, the formation of the coloured developer–dye complex is prevented in the melt.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.003 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 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".