Water-Dispersible, Colloidally Stable, Surface-Functionalizable Uniform Fiberlike Micelles Containing A Pi-Conjugated Oligo(P-Phenylenevinylene) Core Of Controlled Length

pi-Conjugated-polymer-based fiberlike nanostructures show promising potential in applications ranging from biomedicine to microelectronic devices as a consequence of their shape and their intrinsic optoelectronic characteristics. However, these structures can be fragile and subject to dissociation at elevated temperatures or in the presence of certain solvents, and they can be difficult to functionalize. To address these problems, we have synthesized a diblock copolymer containing a pi-conjugated crystalline oligo(pi-phenylene vinylene) (OPV) segment and a poly(3-(triethoxysilyl)propyl methacrylate) (PTESPMA) block (OPV5-b-PTESPMA(35), the subscripts represent the (mean) number of repeat units of each block). Uniform fiberlike micelles of controlled length from 50 nm to similar to 1.2 mu m with an OPV core were obtained by self-seeding in ethanol. The PTESPMA corona was then cross-linked by an in situ siloxane condensation without micelle aggregation or degradation. The integrity and colloidal stability of micelles were preserved in a good solvent for the OPV block, in a THF/ethanol mixture (v/v = 4/1), and also upon heating in ethanol at 80 degrees C. Amino groups were installed onto the surface of shell-cross-linked micelles via second-step siloxane condensation by employing the Si-OH groups of the shell as anchoring sites. The amino groups can be used for further introduction of desired functionalities, e.g., Rhodamine B. In addition, trimethylammonium groups were incorporated onto the surface of micelles. These cationic groups not only endow the micelles with excellent colloidal stability in water without micelle aggregation and fragmentation but also enable the micelles to bind double-stranded DNA. In this way, they may possibly serve as vectors for gene therapy. This work opens a new avenue toward pi-conjugated-polymer-based fiberlike nanostructures with excellent length tunability, mechanical and colloidal stability, and a capacity for surface functionalization.