Fabrication of Thermochromic and Thermal-Energy Storage Microcapsules with a Novel Poly(methyl methacrylate-co-methacrylamide) Shell and Their Applications to Cotton Using Pad-Dry-Cure and Exhaustion Method

Abstract

This study focuses on the development of cotton fabrics that will be able to change color depending on the temperature variation and the thermo-regulation properties of the materials. A novel reversible thermochromic (RTC) microcapsule with poly(methyl methacrylate-co-methacrylamide) (P(MMA-co-MA)) shell was produced by encapsulating leuco-dye based on thermochromic materials (LDBTM) through oil-in-water emulsion polymerization, which exhibited outstanding thermochromic coloration, excellent thermal energy storage/release capacity, and thermo-regulation performance. The thermochromic and thermal characteristics of the microcapsules were examined, and their characterization, including surface morphology, particle-size distribution, and chemical structure, was investigated. Microcapsules presented spherical shape with an average particle size of 19.17 µm. The results obtained from UV–visible absorption spectra and photographs of the microcapsules showed that the microcapsules changed colors from blue to colorless when heated. Differential scanning calorimetry (DSC) and T-history analysis results indicated that microcapsules had high thermal energy storage/release performance (219.5 J/g) and thermo-regulation properties. The microcapsules were incorporated into the cotton fabrics through pad-dry-cure and exhaustion methods. According to the photographic images and colorimetric measurement results, microcapsule-treated fabrics by both application process showed excellent thermochromic performance. However, the microcapsule-treated Fabric 2 via the exhaustion process exhibited better performance compared to Fabric 1, which was prepared using the pad-dry-cure process. Based on the air permeability test results, both microcapsule application process resulted in filling of the fabric pores, which significantly reduced the permeability values. In addition, it was observed that both application methods increased the bending resistance of fabrics while reducing their tear strength.