Functionalization and wear behavior of organic coatings correlated by confocal Raman microscopy

Organic powder coatings are increasingly being used as environmentally friendly protective materials, and advanced characterization can provide information on their performance and durability in service. Epoxy-polyester (EP-PE) hybrid powder coatings were functionalized for the first time with Zn-containing hydrotalcite particles (1% and 3% by weight) to improve their mechanical properties and wear durability. A non-functionalized EP-PE coating was used as a reference. The main novelty of this research consists of the demonstration of using confocal Raman microscopy to correlate the structure-property relationships in organic coatings, extending its application beyond conventional phase identification. Comprehensive characterization was performed to relate the influence of functionalization to polymer chain mobility, mechanical performance and tribological behavior of the coatings. The results showed that the addition of hydrotalcite partially restricts polymer chain mobility, as evidenced by the slight increase in glass transition temperature (T g ) and coating stiffness, resulting in a 45% improvement in wear resistance, measured as wear track depth. The changes in characteristic Raman bands related to aromatic stretching vibrations (C H and C C, at ∼3071 and ∼ 1615 cm −1 , respectively), showing a blue-shift after the addition of hydrotalcite, confirm a more rigid molecular environment. Raman band shifts reflected the polymer stiffening induced by functionalization. Raman measurements on the wear tracks also reveal changes in Raman band positions, demonstrating that the non-functionalized coating experienced more severe structural degradation due to wear. Furthermore, the ∼3071 cm −1 Raman band was identified as a particularly sensitive marker of both functionalization and wear-induced damage. This approach highlights the potential of confocal Raman microscopy to monitor wear-induced chemical transformations and contributes to understanding the relationship between molecular structure and macroscopic performance in advanced organic-inorganic coatings.