Synthesis of poly(3-hexylthiophene)-block-poly(phenylisocyanide) copolymers and their self-assembly in solution

Self-assembly of block copolymers (BCPs) is a widely utilized method to prepare different kinds of nano-objects in solution. Herein, poly(3-hexylthiophene)-block-poly(phenylisocyanide) (P3HT-b-PPI) copolymers were synthesized via nickel-catalyzed living polymerization, and 3-phenylpropyl l-valinate of the second PPI block was successfully introduced into the P3HT-based backbone as verified by NMR, FT-IR spectroscopy and SEC analysis. The self-assembly behaviour of these block copolymers was thoroughly explored via a combination of atomic force microscopy (AFM), transmission electron microscopy (TEM) and other optical property measurements in the new polymeric system. Various polymer nano-assemblies with three main morphologies from spheres and short rods to nanofibers were obtained, and the existence of valine-based 3-phenylpropyl attachments endues the block copolymer with the ability to accomplish judicious self-assembling processes. Moreover, these readily-synthesised and assembled pi-conjugated copolymers are valuable scaffolds for the potential usage of circularly polarised luminescence and liquid crystalline alignment medium.