**3. Results and Discussion**

*3.1. Characterization of Bi-MIPs, Bi-NIPs, Si-MIPs and Si-NIPs* 3.1.1. SEM

The surfaces of Bi-MIPs, Bi-NIPs, Si-MIPs and Si-NIPs were analyzed using a scanning electron microscope. The most representative SEM images of all particles including Bi-MIPs, Bi-NIPs, Si-MIPs and Si-NIPs are shown in Figure 2. The SEM results show that were differences in the polymerization process in the presence of the template or without it. From Figure 2a–d, the as-synthesized polymers products present a regular and spherical structure with a diameter size of about 1–2 μm. The pore volume and surface area of the Bi-MIPs are 4.459 × <sup>10</sup>−<sup>3</sup> cm3/g and 2.8488 ± 0.1059 m2/g, respectively. The Bi-MIPs and Bi-NIPs particles are the same, but the Bi-MIPs have more surface folds, which can provide more adsorption sites [19,42]. The results show that the chrysin occupies a position on the polymer surface during the synthesis process. After elution with methanol and acetic acid, the surface of the Bi-MIPs becomes more wrinkled than that of Bi-NIPs. However, some clustered small particles remain on the surface of the Bi-MIPs, which shows that the template molecules had a remarkable effect on the shape and adsorption properties. This is due to the addition of template molecules in the synthesis of Bi-MIPs, which have a larger particle size and more surface adsorption sites due to the presence of template molecules that give the crosslinking agent and functional monomers a fuller skeleton. The Si-MIP particles are smaller than the Bi-MIP particles, which indicates that the number of functional monomers has a significant influence on the formation of particles and the final particle size. These results suggest that the Bi-MIPs are successfully synthesized.
