*3.1. Morphology*

Figure 1 shows the SEM images of the cross-section fracture surfaces of PBAT/Ti3C2TX nanocomposite films. In Figure 1a,b, PBAT-0 exhibits a relatively smooth surface due to its brittle fracture after immersion in liquid nitrogen [37]. With the addition of Ti3C2TX nanosheets, the surfaces of the PBAT/Ti3C2TX nanocomposites become gradually rough in Figure 1c–f when the Ti3C2TX content is lower than 2.0 wt%. This is due to the presence of Ti3C2TX, which served as a rigid filler to transfer the stress during facture. In addition, it can be seen that an agglomeration phenomenon existed on the surface of PBAT-2.0 (Figure 1g,h). In Figure 1, no pores and holes are observable between the exposed Ti3C2TX nanosheets on the surfaces (Figure 1f,h) and the PBAT matrix, indicating that Ti3C2TX nanosheets have good compatibility with the PBAT matrix. It is attributed to the large number of polar groups of Ti3C2TX that can react with the polyester groups of PBAT.

**Figure 1.** SEM images of the cross-section PBAT/Ti3C2TX nanocomposite films. (**a**,**b**) PBAT-0, (**c**,**d**) PBAT-0.5, (**e**,**f**) PBAT-1.0, and (**g**,**h**) PBAT-2.0.
