Development of photo-modulated non-toxic and adhesive smart gel films

Novel technologies combined with sustainable polymers have great importance for future developments. Polysaccharide gel and films present advantages of safety, renewability, and biodegradability. In this study, unmodified alginate was formulated with non-toxic components to be utilized in UV-induced printing and presented as an eco-friendly visual intelligent device. Riboflavin (RF) degradation upon UV and pH exposure was utilized to achieve photo-modulated specific patterns at 405 nm in SLA (Stereolithography) printer. They were successfully fabricated through an acid-induced ionic gelation process and printed via a UV-induced patterning process. 0.01% (w/v) riboflavin, 60:120 mM CaCO 3 : GDL concentration, printing time as 90 min, and sample volume as 15 ml/petri dish area led to a satisfied performance on UV-induced writing property giving contrast between written and blank regions as well as good texture. Due to the importance of pH and NH 3 sensitivity of the gel films in food packaging, the colorimetric measurements proceeded. The results gave a tendency to more rapid color loss in alkaline conditions than in acidic environments indicating potential food storage applications. According to ammonia vapor sensitivity S (%), the films gave approximately half the value of S compared with the gels. Microstructural changes after the gelation process were also confirmed by FTIR. Photopatterning process on the pH responsive riboflavin enabled multipurpose photopatterning such as monitoring real-time freshness attaching to the inside or outside of the food storage material.