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Photochromic Microcapsules for Textile Materials by Spray Drying—Part 1: Production and Characterization of Photochromic Microcapsules

This study, which is the first in a three-part series, deals with the encapsulation of photochromic dyes by spray drying. An aqueous ethyl cellulose dispersion and a spirooxazine-based photochromic dye were used as a shell and core material, respectively. The effects of main encapsulation parameters, such as solvent type, inlet temperature, feed rate, solid content, and aspirator rate were investigated. The encapsulation results were evaluated by scanning electron microscopy (SEM) images, particle size measurements, thermogravimetric analysis (TGA) and X-ray diffraction (XRD). The microcapsules obtained from a water-ethanol mixture exhibited photochromic properties. For microcapsule production, the optimum feed rate, total solid content, and aspirator rate were determined. Capsule formation improved with increased inlet air temperature. Spray drying to produce photochromic microcapsules could be a practical method for production of photochromic smart textiles.