Smart organic/inorganic hybrid nanoobjects with controlled shapes by self-assembly of gelable block copolymers

A series of well-defined functional gelable diblock copolymers, poly(3-(triethoxysilyl)propyl methacrylate)-block-poly(2-vinylpyridine) (PTEPM-b-P2VP), were synthesized by a two-step reversible addition-fragmentation chain transfer (RAFT) mediated radical polymerization procedure. The self-assembly of PTEPMb-P2VP diblock copolymers in the bulk was studied by a combination of small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). With change of the copolymer composition, three different microphase-separated morphologies, i.e., lamellae, hexagonally packed cylinders, and spheres, were obtained. The in-situ self-gelation was subsequently carried out under hydrochloric acid vapor to lock the PTEPM phases. By dispersing the gelated bulk materials with ordered structures in an acidic water solution (pH = 3), the isolated organic/inorganic hybrid nanoobjects with controlled shapes including plates, cylinders, and spheres bearing protonated P2VP hairs were prepared. By deprotonation of the P2VP hairs, these novel nanoobjects may precipitate from the solution, and therefore, they are pH-sensitive. Furthermore, when applying these hybrid nanoobjects with P2VP hairs as the templates for supporting gold nanoparticles, novel pH-responsive functional nanoobjects with Au nanoparticles organized in different dimension were obtained.