## 3 Results and Discussion
### Inhibitor Releasing Characteristics and Mechanism of OIMs@PAM
#### 3.2.4 GE-EP@OIMs Morphology After Inhibitor Release  
Figure 11 shows the macroscopic morphology of GE-EP@OIMs after immersion in NaCl solutions at 20 \({}^{\circ}\)C, 50 \({}^{\circ}\)C, and 80 \({}^{\circ}\)C for 60 days. The initial GE-EP@OIMs samples were yellow-brown cylindrical solid substances with a diameter and height of 20 mm and an average weight of 15.7377 g. The color of the solid corrosion inhibitor was primarily attributed to the organic corrosion inhibitor components. At 20 \({}^{\circ}\)C, the color of the GE-EP@OIMs sample gradually changed from yellow-brown to yellow over time, with no significant color change after 30 days. This indicates that the sample released the corrosion inhibitor slowly at low temperature (20 \({}^{\circ}\)C), and the effective release time was approximately 30 days.  
Figure 10: Release mechanism of GE-EP@OIMs under different temperature environments.  
At 50 \({}^{\circ}\)C, the sample initially faded from yellow-brown to yellow and then turned light yellow after 60 days. This indicates that the solid corrosion inhibitor was released continuously and stably, with an effective release time of approximately 60 days. In the 80 \({}^{\circ}\)C solution, the sample released the corrosion inhibitor quickly, fading to light yellow within 50 days. The sample exhibited cracks on the surface, and its mechanical strength decreased. By 60 days, the sample had completely turned pale white, with OIMs almost entirely released, and the cracks on the surface deepened. These macroscopic morphological changes suggest that the sample can rapidly release the OIM corrosion inhibitor in a high-temperature environment, leading to quick and effective corrosion protection for carbon steel in more corrosive conditions. However, the downside is that the effective protection time of the solid corrosion inhibitor is also shortened. This finding is consistent with the cumulative release curve of the solid corrosion inhibitor.  
Figure 12 presents the internal SEM image of GE-EP@OIMs after being released in NaCl solutions at 20 \({}^{\circ}\)C to 80 \({}^{\circ}\)C for 60 days. From the image, it can be observed that in the 20 \({}^{\circ}\)C solution, numerous pits appeared in the internal cross-section of the GE-EP@OIMs sample, with gel swelling observed at the edges of the pits. This swelling is due to the gelatin dispersed within the sample continuing to absorb water and swell at low temperatures. In contrast, the gelatin in the sample dissolves in medium- and high-temperature solutions [40]. In the 50 \({}^{\circ}\)C environment, the sample exhibits a \"honeycomb-like\" network structure with numerous micropores and small holes ranging from tens to hundreds of micrometers in diameter. As the gelatin dissolution rate increases with higher solution temperatures, the number of micropores below 100 \(\upmu\)m in the 80 \({}^{\circ}\)C environment is lower than in the 50 \({}^{\circ}\)C environment. However, the number of pores ranging from 100 to 500 \(\upmu\)m is significantly higher at 80 \({}^{\circ}\)C, and the pores extend deeper into the sample. This facilitates the rapid and extensive release of OIMs from GE-EP@OIMs at high temperatures, although it also reduces the effective release time.  
Figure 11: Macroscopic morphology of GE-EP@OIMs immersed in NaCl solution at 20 \({}^{\circ}\)C, 50 \({}^{\circ}\)C, and 80 \({}^{\circ}\)C for different time periods.