Fourier transform infrared spectroscopy analysis
The microcapsules, which had undergone pretreatment with HPH emulsion and MF emulsion, were analyzed using Fourier-transform infrared spectroscopy (FTIR) with a Thermo Nicolet instrument located in Waltham, Massachusetts, USA. To facilitate analysis, all samples were mixed with solid KBr powder, and the transmission of wave numbers within the range of 4000 to 500 cm−1 was recorded.