# Evidence: critical entanglement molecular weight

Parent: — · class: solution behaviour · names merged here: critical entanglement molecular weight; critical molecular weight for entanglement

2 papers measured or used it, 0 only mentioned it (of 207 kept papers). Papers in year order; each section heading ends with the paper's category / subcategory. Generated by tools/build_evidence.py from registry/concepts.csv and the cards; do not edit.

## 2023 Bapat — Does Media Choice Matter When Evaluating the Performance of Hydroxypropyl Methylcellulose Acetate Succinate-Based Amorphous Solid Dispersions? · Dissolution / A. Release mechanism and LoC

[2023-bapat-hpmcas-asd-media-choice-buffer-capacity-release](../../../cards/2023-bapat-hpmcas-asd-media-choice-buffer-capacity-release/paper.html) · Dissolution / A. Release mechanism and LoC · used · as: critical molecular weight for entanglement

| id | kind | content | locator |
|---|---|---|---|
| C34 | claim, prior hypothesis, authors: "expected"; "may" | Polymers above the critical molecular weight for entanglement form a gel layer in a good solvent because solvent penetrates faster than chains disentangle; polymers near or below it may still form a swollen gel through viscosity effects [rests on: cited: ref 59] | p.5720 |
| C45 | claim, mechanism, authors: "unlikely"; "likely"; "consistent with"; "further support"; "certainly for the case of the neat polymer" | HPMCAS-MF, although it forms a thin removable gel layer in some media, is unlikely to form molecular entanglements: its MW (∼18,000 Da) is below estimated critical values of other polysaccharides, and no plateau appears in rate versus rotation speed^0.5 even for the pre-ionized salt, so dissolution is diffusion- rather than disentanglement-controlled, certainly for neat polymer [rests on: R14, R18, R19, R27; cited: ref 69] | p.5724 |
| R27 | record, cited | estimated critical molecular weight for entanglement of other polysaccharides — pullulan, curdlan, xanthan (no reference given) — ∼22, 24 and 34 kDa | p.5724 |

## 2024 Deac — Dissolution mechanisms of amorphous solid dispersions: Role of polymer molecular weight and identification of a new failure mode · Dissolution / A. Release mechanism and LoC

[2024-deac-asd-polymer-molecular-weight-failure-mode-loc](../../../cards/2024-deac-asd-polymer-molecular-weight-failure-mode-loc/paper.html) · Dissolution / A. Release mechanism and LoC · used · as: critical entanglement molecular weight

| id | kind | content | locator |
|---|---|---|---|
| E1 | equation | critical molecular weight for chain entanglement (Wool): Mc ≈ 30 C∞ M0 | p.4 |
| R12 | record, derived (P5) | LoC per PVP grade, LoC = highest DL at which drug release exceeded 80% — R1; grades M2-M7 — sub-table below; Fig. 7 also draws the Mc line (dashed red) between K25 and K29/32, labels the grades left of it "Failure Mode I" and right of it "Failure Mode II", and shades a "Phase Inversion Region" from 30 to 40% DL across all grades (caption: inferred for K17, K25, K60 and K90 from K12 and K29/32 data); text: LoC below 5% for K12 and K17, rising to over 30% across a narrow MW threshold close to Mc, with minimal further increase above it | Fig. 7, p.9; text p.9 |
| C37 | claim, conclusion, authors: asserted ("surprising") | Polymer molecular weight had a surprising effect on the LoC: below 5% for K12 and K17, then a rapid rise to over 30% DL across a narrow MW threshold close to Mc, with minimal further increase above it [rests on: R12, R1, M2-M7] | p.9 |