pH-Modulated 1D Hierarchical Self-Assembly of a Brush-Like Poly-Para-Phenylene Homopolymer.

ABSTRACT

The controllable self-assembly of conjugated homopolymers, especially homopolymers without other segments (a prerequisite for phase separation), which can afford chances to achieve tunable optical/electronic properties, remains a great challenge due to their poor solubility and has remained rarely documented. Herein, a conjugated homopolymer (DPPP-COOH) is synthesized, which has a unique brush-like structure with a conjugated dendritic poly-para-phenylene (DPPP) backbone and alkyl-carboxyl side chains at both edges of the backbone. The introduction of carboxyl makes the brush-like homopolymer exhibit pH-modulated 1D hierarchical self-assembly behavior in dilute solution, and allows for flexible morphological regulation of the assemblies, forming some uncommon superstructures including ultralong nanowires (at pH 7), superhelices (at pH 10) and "single-wall" nanotubes (at pH 13), respectively. Furthermore, the good aqueous dispersibility and 1D feature endow the superstructures formed in a high-concentration neutral solution with high broad-spectrum antibacterial performance superior to that of many conventional 1D materials.