Fig 6.

(A) Microscopic images of polyester composite coating surfaces (4.5% SiO₂NPs) before and after 3 years of environmental exposure to tropical (Singapore) and sub-tropical (Queensland) climates (from top to bottom). (B) Low-resolution synchrotron macro ATR-FTIR chemical maps of the ν(C = O) band at 1725 cm^-1, acquired on the same area shown in the corresponding microscopic images. (C) High-resolution synchrotron macro ATR-FTIR 3D chemical maps of the ν(C = O) band at 1725 cm^-1, acquired on specific areas of interest as indicated in (B).