Thermochromic and/or photochromic properties of electrospun cellulose acetate microfibers for application as sensors in smart packing

There is growing demand for smart materials whose chemical structure, shape, and/or color, among other properties could be modified for use in applied packaging in the food industry, pharmacy, textiles, and so forth. These variations results from external stimuli, whether chemical, physical, and/or environmental (humidity, heat, light, and so forth), which has created promising materials for use in various areas of engineering, such as the production of ultrasensitive sensors with the capacity that the said variations are perceptible to the naked eye. The production of nanostructured sensor membranes obtained by electrospinning is one interesting alternative that has been attracting the attention of researchers in recent years. However, many studies related to the application of photosensors supported in electrospun cellulose acetate (CA) have not been found in the literature. Among the most used materials in electrospinning, CA stands out due to its wide availability and low cost that reflects in several applications. Two commercial sensitive pigments were used, a thermosensitive and a photosensitive one, in concentrations between 0 and 10% (m/v), to evaluate the best amount in the nanosensors they could be seen through naked eye. Variation on the fibers morphology was characterized by scanning electron microscopy. The stability and thermal transitions were evaluated using thermogravimetric analysis/differential thermogravimetric analysis and differential scanning calorimetry. The composition of chemical fibers was studied using FTIR-ATR. Finally, the thermal and/or UV light response was performed by qualitative test.