Study On Microencapsulation Of Reversible Thermochromic Materials

In this paper, the preparation of the RTM/EC thermochromic microencapsule and their application in coating and paint is presented. Using ethyl cellulose (EC), polyisobutylene (PIB) , cyclohexane (HC) and Span80 to prepare RTM/EC thermochromic microencapsule by oil phase separation method in which EC, PIB, HC and Span80 are used as shell material, phase stabilizer, solvent and emulsifier respectively. The roles which act on the embedding efficiency and particle size of the RTM/EC thermochromic microencapsule played by four factors: shell material content, stabilizer content, solvent content and emulsifier concentration and two techniques: the rate of stiring and the time of phase separation in the formation of the RTM/EC thermochromic microencapsule are investigated. The relation between the embedding efficiency and particle size and the thermochromism performance of the RTM/EC thermochromic microencapsule and the mechanism of oil phase separation are discussed. Microstructure of the RTM/EC thermochromic microencapsules are characterized by Biomicroscope, Scanning Electron Microscopy, Differential Scanning Calorimeter, Thermogravimetric Analysis and Transmission Electron Microscope. The structure and thermochromism performance of the RTM/EC thermochromic microencapsule are researched systematically. And the heat resistance, solvent resistance, chemical stability and polymer compatibility of the RTM/EC thermochromic microencapsule are investigated. Then the effects on thermochromism and project performance of the coating and paint in different content of the RTM/EC thermochromic microencapsule are discussed.The results presented here offer an outstanding RTM/EC thermochromic microencapsule and show that the reversible thermochromism, environment adaptability and polymer compatibility of the RTM/EC thermochromic microencapsule are improved by microencapsulation. The temperature of color changing of the RTM/EC thermochromic microencapsule is 41 ℃, while the time of color changing ,the time of color fading and the sensitivity of color changing of the RTM/EC thermochromic microencapsule are 15s, 10s and 0.6 respectively .And it's color changes reversibly from pink to sky blue. As a conclusion, the thermochromic coating and the thermochromic paint have high performances and prospected applications.