Fig. 4. (A) Comparison between FTIR-ATR spectra of: BER (blue line); H-SMA (black line); H-SMA-BER (red line); (B) comparison between FTIR-ATR spectra of: NR16 (blue line); H-SMA (black line); H-SMA-NR16 (red line); the starting materials used to form the encapsulated systems (H-SMA and BER), subjected to FTIR-ATR analysis, showed spectroscopic characteristics identical to those reported in the literature.^35,36 In the H-SMA copolymer, the carboxyl band appeared at 1703 cm⁻¹ and a strong absorption band was observed at 1454 cm⁻¹ (COO⁻ symmetric vibrations), while a weak band (C–H stretching of the aromatic rings) was present at 3028 cm⁻¹ (Fig. 4A).