Abstract
This study developed pH-indicator films by combining esterified cellulose nanocrystals (e-CNCs) with activated bromocresol purple (a-BCP) via covalent bonding for pH-sensitive color-changing applications. The e-CNC/a-BCP particles were incorporated into cellulose acetate polymer to prepare pH-sensitive color changing films. Binding of a-BCP to e-CNCs was proven by attenuated total reflection infrared (ATR-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Colorimetric analysis showed that films containing 10% or 15% e-CNC/a-BCP particles had critical color changes either at pH 4–5, or pH 7–8. The films with 10% e-CNC/a-BCP particles also revealed excellent leaching resistance under acidic conditions. Color changes were reversible between pH 2 and 10. These pH-indicator films had visible color changes in response to pH variations, color reversibility, leaching resistance, and sufficient rigidity even though mechanical properties decreased as the e-CNC/a-BCP content increased from 0% to 15%.
| Original language | English |
|---|---|
| Article number | 118550 |
| Journal | Carbohydrate Polymers |
| Volume | 273 |
| DOIs | |
| State | Published - 1 Dec 2021 |
Keywords
- Bromocresol purple
- Cellulose nanocrystals
- Color changing films
- pH-indicator films
- Reversibility