Preparation of poly(methyl methacrylate) photochromic microcapsules containing spiro-pyran by solvent volatilization

Abstract

In this study, poly(methyl methacrylate) (PMMA) microcapsules containing photochromic spiro-pyran dyes were prepared by the solvent volatilization method. The effects of different core-to-shell ratios, emulsifier dosage and temperature on the yield, size and morphology of PMMA microcapsules were investigated. The results showed that the highest yield was achieved when the core-to-shell ratio was 2:1, the amount of emulsifier was about 2% of the aqueous phase, and the volatilization temperature should be controlled at about 35 °C. Scanning electron microscopy (SEM) images and particle size analysis showed that spherical microcapsules were formed with an average particle size of about 2 μm. The photochromic microcapsules have excellent thermal stability and can withstand a temperature of 300 ℃; the color change response performance is excellent and the color can reach saturation within 14 s. The prepared photochromic microcapsules were screen printed on cotton fabric, and scanning electron microscope (SEM) images showed that there was an attachment between the photochromic microcapsules and the fibers. The K/S values of the printed cotton fabrics were almost unchanged by UV light cyclic irradiation for 30 consecutive times, indicating that the printed cotton fabrics have excellent color change and fatigue resistance. The photochromic fabric responds quickly to color change under UV light irradiation and reaches saturation color depth after 30 s.