## 3 Results and Discussion  
### SEM and FTIR Analysis  
The morphological changes to CO and PET fibers induced by impregnation with the PANI/TiO\({}_{2}\) nanocomposite were assessed by FESEM analysis. SEM images of control CO and PET fibers and of the fibers impregnated with nanocomposite once or twice are presented in Figure 2. SEM images of each sample were intentionally taken under three different magnifications (\(\times\)10,000, \(\times\)20,000, \(\times\)100,000) with an aim not only to confirm the presence of nanocomposite, but to estimate how much it covers the fiber surface and to gain insight into its morphological structure. Fibers are an integral part of the fabrics, and the coating efficiency of fibers either on the fabric surface or inside the yarns in inner parts of the fabrics should be uniform. In other words, the coating efficiency of fabrics is determined by the coating efficiency of the fibers. Imaging of fabrics under lower magnification cannot provide any information on the coating efficiency as it is impossible to distinguish since a very thin nanocomposite layer was formed. By proceeding with imaging under lower magnification it is possible only to get information on the construction of the fabrics. The SEM image of CO fiber reveals characteristic folds running parallel to the elongation direction of the pristine fiber. Single impregnation of CO fabric with PANI/TiO\({}_{2}\) nanocomposite (CO-PANI/TiO\({}_{2}\)-1) resulted in the formation of a relatively uneven and thinner layer of nanocomposite. In other words, some segments were not fully covered with nanocomposite. It was noticed that the uniformity of CO-PANI/TiO\({}_{2}\)-1 fiber impregnation significantly varied from fiber to fiber, and it was the least uniform when compared to other samples. There was also an obvious difference between the fibers on the thread surface and those positioned inside the threads. Double impregnation (CO-PANI/TiO\({}_{2}\)-2) induced the formation of a much thicker layer of nanocomposite which actually covered the whole surface of the fibers. Rod-like nanostructures of PANI/TiO\({}_{2}\) established a network on the PET fiber surface. The average diameter of the nanorods was approximately 50 nm. Such networked structures have been reported in literature, and they are a characteristic feature of PANI [29]. Eventually, the larger the amounts of generated nanocomposite, the larger the fiber diameter. As expected, the SEM images demonstrated the smooth surface of PET fibers. Our previous study implied that the morphology of the PET fiber surface impregnated with pure PANI significantly differs from that of PET fibers coated with PANI/TiO\({}_{2}\) nanocomposite [30]. No signs of a PANI layer could be observed on the PET-PANI fibers, with only small patches of polymer randomly deposited over the fiber surface instead. The SEM images presented in Figure 2 clearly show that the presence of TiO\({}_{2}\) NPs (mostly single crystalline, irregularly shaped NPs with average dimensions of 4.5 nm and anatase crystal structure [24]) strongly affected the polymerization of ANI, providing a completely different fiber surface morphology. The SEM image of PET-PANI/TiO\({}_{2}\)-1 fibers indicated that the amount of synthesized nanocomposite was considerably larger when compared to CO-PANI/TiO\({}_{2}\)-1 fibers modified under the same conditions. However, the thickness of nanocomposite varied even on a single fiber. The images taken under the highest magnification also revealed the appearance of a nanorodnetwork on the PET fiber surface which highly resembles the morphology of the CO-PANI/TiO\({}_{2}\)-2 sample. It is clear that the PET-PANI/TiO\({}_{2}\)-2 fibers were entirely covered with huge amounts of polymer but the shape of the fibers was preserved. Like in the case of CO fibers, double impregnation led to the formation of larger amounts of nanocomposite when compared to single impregnation. However, instead of a nanorod networked structure, a very porous structure with differently shaped nanoplates appeared.