# Formula: Δχ effect

Parent: — · class: mixing and phase equilibria · names as written: solvent Δχ effect (ternary Flory–Huggins); Δχ effect; Δχ effect (solvent-interaction asymmetry)

3 instances in 3 papers (of 207 kept papers). Each section heading ends with the paper's category / subcategory. Generated by tools/build_evidence.py from registry/formulas.csv; do not edit.

## 2010 Marsac · E1 · Δχ effect (solvent-interaction asymmetry) · Solid state stability / Physical stability

[2010-marsac-temperature-moisture-miscibility-felodipine-pvp-asd](../../../cards/2010-marsac-temperature-moisture-miscibility-felodipine-pvp-asd/paper.html) · Solid state stability / Physical stability

- expression: abs(Δχ) = abs(χ12 − χ13) (printed with absolute-value bars)
- symbols and units: χ12 Flory–Huggins interaction parameter water–felodipine; χ13 water–PVP; dimensionless; index 1 = water (solvent), 2 = felodipine, 3 = PVP (χ23 = felodipine–PVP)
- assumptions stated: phase separation is promoted when the two components interact asymmetrically with the solvent (refs 39, 40)
- used for: R22
- status: printed, checked against page image · recomputed: not applicable (no Δχ value printed; the printed inputs give abs(3.3 − 0.5) = 2.8)
- locator: p.182

## 2017 Purohit · E4 · Δχ effect · Dissolution / A. Release mechanism and LoC

[2017-purohit-ritonavir-asd-hydration-dissolution-phase-behavior](../../../cards/2017-purohit-ritonavir-asd-hydration-dissolution-phase-behavior/paper.html) · Dissolution / A. Release mechanism and LoC

- expression: Δχ = abs(χ_WD − χ_WP), stated in words as the magnitude of the difference between χ_WD and χ_WP; the larger Δχ, the higher the tendency for phase separation
- symbols and units: χ_WD water-drug and χ_WP water-polymer interaction parameters
- assumptions stated: named effect of ref 31
- used for: none (argument only; C43, C46)
- status: printed in words · recomputed: not applicable (no χ values stated)
- locator: pdf p.15

## 2021 Yang · E2 · solvent Δχ effect (ternary Flory–Huggins) · Dissolution / A. Release mechanism and LoC

[2021-yang-asd-nanodroplet-release-drug-properties-polymer-selection](../../../cards/2021-yang-asd-nanodroplet-release-drug-properties-polymer-selection/paper.html) · Dissolution / A. Release mechanism and LoC

- expression: abs(Δχ) = abs(χ12 − χ13) (printed with absolute-value bars)
- symbols and units: 1 solvent; 2 and 3 the two blend components; χ12, χ13 Flory–Huggins interaction parameters of solvent with each component; χ23 interaction parameter of the two components without solvent
- assumptions stated: phase separation predicted when abs(Δχ) is large enough, even if χ23 is negative or small (ref 45)
- used for: C21 (no record)
- status: printed, checked against page image · recomputed: inputs not printed (no χ values)
- locator: Eq. 2, p.2077