Integrating Green Chemistry and Materials Science: A Blueberry Anthocyanin-Based pH Indicator Film Experiment for Undergraduate Laboratory Education

This laboratory experiment provides undergraduate students with an introduction to functional film materials (FFMs) through the design and fabrication of pH-responsive indicator films. In this experiment, blueberry anthocyanins (BA) are incorporated into a carboxymethyl cellulose (CMC) and xanthan gum (XG) matrix stabilized by citric acid, resulting in films that display distinct and pH-responsive color change from pink (pH 2) to purple (pH 7) and to brown (pH 12). The 3 h module provides a hands-on investigation of structure–property relationships, allowing students to correlate molecular transformations with macroscopic color changes. The experiment incorporates green chemistry principles by employing natural pigments and reducing reagent consumption, while simultaneously fostering core competencies in material synthesis, mechanical testing, and analytical applications. The films exhibit robust mechanical properties, ensuring durability during student handling, and their extension to ammonia gas sensing further illustrates cross-disciplinary adaptability. Implemented in the Functional Materials curriculum (semesters 3–4), this low-cost, simple-equipment approach connects theoretical concepts from Materials Science and Smart Materials courses, fostering system-level thinking and industry-relevant problem-solving skills.