Effect of Different Emulsifiers on the Preparation Process of Aloe-Emodin Microcapsules and Waterborne Coating Properties

Abstract

Using microencapsulation technology and the natural antimicrobial properties of aloe-emodin, the antimicrobial microcapsules were prepared by in situ polymerization using urea-formaldehyde resin as the wall material and aloe-emodin as the core material. The antimicrobial microcapsules were mixed into waterborne coatings to improve the antimicrobial ability of waterborne paint films against bacteria for better protection of substrates. The purpose of this study was to optimize the preparation process of aloe-emodin antibacterial microcapsules. With the variety and concentration of emulsifiers as the changing factors, three different emulsifiers, namely sodium dodecyl benzene sulfonate SDBS, OP-10, and Tween-80, were selected to explore the effects of emulsifier type and microcapsule loading on the physicochemical and the antibacterial properties of waterborne paint films, and the morphology, chemical composition, antibacterial properties, optical properties, and roughness of the paint films were tested and analyzed. The results showed that all the emulsifiers with 3.0% concentration in the microencapsulation preparation were better than 1.0%. The performance of the microencapsulated varnish films prepared with the addition of the three emulsifiers had advantages and disadvantages, with the highest antibacterial rates of 77.1%, 55.4%, and 65.9% for Escherichia coli and 70.0%, 63.9%, and 60.7% for Staphylococcus aureus, respectively. The antibacterial properties of the microencapsulated varnish film prepared by adding SDBS emulsifier were slightly above those of the other two groups. The three sets of paint films’ color differences rose, the gloss reduced, the rate of light loss increased, the rate of light transmission fell, and the roughness increased with an increase in microencapsulated content. Aloe-emodin microcapsules enable the water-based coating to have antibacterial properties, expanding the application range of water-based coatings.