## 3 Results
### Transparency and Tensile Strength  
The transparency of ADIP-PS sheets was assessed using a transmittance measurement device. The highest-yield sample, AD-23K, was blended with GPPS at various ratios and molded into sheets. Figure 3a shows the sheets having the thicknesses listed in Table 3. \"Neat PS\" refers to sheets formed from virgin GPPS pellets, whereas \"PS\" refers to sheets formed from GPPS pellets after heat blending. Sheets made solely from ADIP-PS (100% AD-23K) were brittle and unsuitable for forming the 2 cm diameter sheets required for transparency evaluation. Other sheets were successfully molded to a uniform thickness of 1.9 mm.  
As the ADIP content increased, moderate absorption occurred on the blue side of the visible light region, resulting in a yellow color (Figure 3a). The yellow color is due to the absorption in the UV region (around 250 nm) of imidazolium, as shown by reported absorption spectra [34]. Further, in the 25%_AD-23K samples, absorption occurred across the entire visible light range, and the material became cloudy because of molecular-level insufficient kneading originating from the significant difference in the molecular weights of GPPS and ADIP-PS (Figure 3b). In the 25%_AD-23K samples, absorption across the visible light range and insufficient molecular-level mixing were caused by the significant difference in the molecular weights of GPPS and ADIP-PS, resulting in cloudiness (Figure 3b). Comparing \"Neat PS\" with \"PS\", the heat treatment of GPPS slightly reduced the light absorbance without significantly altering the appearance (Figure 3a), indicating minimal effects from heating. Therefore, the reduction in absorbance observed in the >25% ADIP-PS blends is primarily because of ADIP-induced discoloration and insufficient blending from molecular-weight differences. When the ADIP-PS content was 10% or less, there were no significant changes in appearance compared to \"Neat PS\" or \"PS\", and the light absorbance was unaffected (Figure 3). Additionally, no noticeable changes were observed in the appearance of each sheet even 8 months after molding (Figure S3).  
The tensile strength of the PS blended with ADIP-PS was also measured. Both 100%_AD-23K and 25%_AD-23K samples were too brittle for tensile testing because of the lower \(M_{\text{w}}\) of AD-23K compared to that of GPPS. Previous studies demonstrated that the factors contributing to the decrease in strength were the reduced entanglement between molecules owing to the smaller molecular weight [35; 36] and the decreased interactions between polystyrene molecules because of the hydrophilic functional groups of ADIP [37; 38]. Figure 4 shows the stress-strain curves, and the tensile strength, fracture strain, and Young's modulus values are listed in Table 4. No significant changes in strength were observed between \"Neat PS\" and \"PS\" after blending, indicating that blending had no impact on PS strength. The tensile strength and Young's modulus of 5%_AD-23K and 10%_AD-23K were only slightly lower than those of pure PS, indicating minimal impact on mechanical strength from blending ADIP-PS with GPPS. Based on the transmittance and tensile  
Figure 2: Antibacterial activity of 100%_ADIP-PS sheets against _S. aureus_. Error bars represent the standard deviation (SD) with \(n=3\).  
strength results, blending ADIP-PS with GPPS at ratios of 10% or lower is optimal for maintaining the transparency and mechanical integrity of polystyrene.  
Figure 4: Stress–strain curves of PS and ADIP-PS (AD-23K) resins.  
Figure 3: Transparency of ADIP-PS (AD-23K) sheets. (**a**) Representative appearance of PS and ADIP-PS sheets. (**b**) Transmittance spectra of PS and ADIP-PS sheets.