Interfacial Assembly of pH-Senstive Bottlebrush Copolymers at the Water-Oil Interface

We synthesized bottlebrush copolymers (BBCPs), specifically poly(tris(trimethylsilyl) silane)-block-poly(2-vinylpyridine) (PTTMSSA-b-P2VP). These BBCPs were fully dissolved in toluene, and the interfacial behavior of their droplets against water was investigated using a pendant drop tensiometer. Upon protonation, the P2VP block became hydrophilic, enhancing its water affinity. This protonation-induced change facilitated the reconfiguration of the BBCPs at the interface. By adjusting the pH, we controlled the degree of protonation. The lowest interfacial tension was observed at a pH below 2.15, although spontaneous wrinkling did not occur at these lower pH levels. Similar behavior to that seen with functionalized nanoparticles was noted. Furthermore, these BBCP solutions acted as surfactants, stabilizing water microdroplets within the oil phase to form emulsion-like systems that remained stable for several days.