## 2 Results and Discussion  
### Structure and Morphology Analysis  
Figure 1 and Table 1 show the FTIR spectra and absorption peaks of TTO, P(St-BMA) microspheres, and TTO microspheres. For P(St-BMA) microspheres, the strong peak observed at 688 cm\({}^{-1}\) and 763 cm\({}^{-1}\) corresponded to the characteristic absorption signals of monosubstituted benzene. The peaks at 2926 cm\({}^{-1}\), 1450 cm\({}^{-1}\), and 1600 cm\({}^{-1}\) could be ascribed to the stretching vibration of the C-H and C-C bonds of the benzene ring, respectively. The peak at 1729 cm\({}^{-1}\) corresponded to the carbonyl stretching vibration absorption peak. There was no obvious absorption peak near 910 cm\({}^{-1}\), indicating that the C=C bond of St and BMA were already cleaved. For TTO, the stretching vibration peak corresponding to the C-H bond appeared at 2965 cm\({}^{-1}\). The peak at 1127 cm\({}^{-1}\) was ascribed to the stretching vibration absorption peak of the C-O bond of the tertiary alcohol in terpen and terpineol, respectively. The peak at 910 cm\({}^{-1}\) corresponded to the bending vibration absorption peak of an unsaturated double bond. For TTO microspheres, the peak at 1729 cm\({}^{-1}\) corresponded to the characteristic peak of TTO [23], covered by a carbonyl absorption peak of TTO microspheres. Compared to P(St-BMA) microspheres, three new absorption peaks for TTO microspheres appeared at 2965 cm\({}^{-1}\), 1127 cm\({}^{-1}\), and 910 cm\({}^{-1}\), corresponding to the characteristic peaks of TTO and further indicating that TTO was adsorbed by the P(St-BMA) microspheres.  
Figure 2(a\({}_{1}\),b\({}_{1}\)) shows particle size diagrams of microspheres before and after TTO absorption. Figure 2a\({}_{1}\) shows that 10 P(St-BMA) microspheres were 0.5 mm long, and the average particle size was about 500 \(\upmu\)m. As shown in Figure 2b\({}_{1}\), after adsorption of TTO the length of 10 TTO microspheres was approximately 14.5 mm, and the average particle size was about 1450 \(\upmu\)m. Figure 2(a\({}_{2}\),b\({}_{2}\)) shows the morphology of P(St-BMA) microspheres and TTO microspheres in an optical microscope. The P(St-BMA) microspheres and TTO microspheres exhibited a spherical shape, and the particle size of the two corresponded to the data shown in Figure 2(a\({}_{1}\),b\({}_{1}\)). As shown in Figure 2(a\({}_{3}\),a\({}_{4}\)), the surface of P(St-BMA) microspheres was rough and concave, because the monomers of St and BMA cross-linked to form a three-dimensional network scaffold in the presence of a DVB crosslinking agent. As shown in Figure 2(b\({}_{3}\),b\({}_{4}\)), compared to the P(St-BMA) microspheres, the surface of TTO microspheres was convex instead of concave. Most likely, this latter finding was due to the three-dimensional network of the P(St-BMA) microspheres forming a porous structure. Furthermore, the density difference between air and TTO was large and the surface tension of TTO was low. As a result, during adsorption of TTO by the P(St-BMA) microspheres, part of the air inside the pores was not completely consumed, resulting in the formation of a liquid film on the surface.  
Figure 1: FTIR spectra of TTO, P(St-BMA) microspheres, and TTO microspheres.