CMC and CNF-based alizarin incorporated reversible pH-responsive color indicator films

Area of Science:

• Materials Science
• Polymer Chemistry
• Analytical Chemistry

Background:

• Cellulose derivatives like carboxymethyl cellulose (CMC) and cellulose nanofibrils (CNF) are versatile biomaterials.
• pH-sensitive dyes, such as alizarin, can undergo color changes in response to varying acidity levels.
• Developing smart materials with tunable properties is crucial for advanced sensing applications.

Purpose of the Study:

• To develop novel pH-responsive color-changing indicator films.
• To investigate the structural and functional properties of these cellulose-based films.
• To evaluate the potential application of these films as gas sensors.

Main Methods:

• Preparation of indicator films using CMC, CNF, and the pH-sensitive dye alizarin.
• Characterization of film structure using X-ray diffraction (XRD).
• Assessment of UV-vis light screening, radical scavenging activity, thermal stability, and pH-dependent color changes.

Main Results:

• The films exhibited a semi-crystalline structure with alizarin incorporation.
• The indicator films demonstrated UV-vis light screening, radical scavenging, and enhanced thermal stability.
• A distinct and reversible color change from yellow to purple was observed in the pH range of 2-12.

Conclusions:

• The developed cellulose-based indicator films are effective pH sensors.
• The films show stable and reversible color changes, suitable for repeated use.
• These pH-responsive films hold promise for use as acid or base gas sensors in packaging environments.