Development and Characterization of Halochromic Polyolefin Films Modified With PEG and Starch for pH‐Sensitive Applications

This study presents the development of halochromic polymer films based on high‐density polyethylene (HDPE), low‐density polyethylene (LDPE), and polypropylene (PP), modified with polyethylene glycol (PEG), and starch (ST), for pH‐sensitive functional applications. The films were prepared through melt blending and compression molding, incorporating bromocresol purple (BCP) as the pH indicator dye. Colorimetric response to ammonia and acid vapors was evaluated alongside thermal, mechanical, morphological, and gas permeability properties. Results showed that PEG enhanced halochromic responsiveness by increasing amorphous regions, while ST improved color uniformity and mechanical integrity. Optimal performance was observed at moderate PEG concentrations (6%), with HDPE blends exhibiting the highest crystallinity and thermal stability. The combined effects of PEG and ST tuning provided control over flexibility, crystallinity, and permeability, underscoring their potential for intelligent packaging and environmental sensing applications.