Synthesis and pH-Dependent Micellization of a Novel Block Copolymer Containing s- Triazine Linkage

Novel pH-sensitive moieties containing an s-triazine ring were synthesized with sulfonamide and secondary amino groups. The synthesized pH-sensitive moieties were used for the synthesis of a pH-sensitive amphiphilic ABA triblock copolymer. The pH-sensitive triblock copolymer was composed of diblock copolymers, methoxy poly(ethylene glycol)-poly ($\varepsilon$-caprolactone-co-D,L-lactide) (MPEG-PCLA), and pH-sensitive moiety. These copolymers could be dissolved molecularly in both acidic and basic aqueous media at room temperature due to secondary amino and sulfonamide groups. The synthesized s-triazine rings containing pH-sensitive compounds were characterized by ${^1}H-NMR,\;{^13}C-NMR$, and LC/MSD spectral data. The synthesized diblock and triblock copolymers were also characterized by ${^1}H-NMR$ and GPC analyses. The critical micelle concentrations at various pH conditions were determined by fluorescence technique using pyrene as a probe. Furthermore, the micellization and demicellization study of the triblock copolymer was done with pH-sensitive groups. The sensitivity towards pH change was further established by acid-base titration.