Synthesis and solution self-assembly of polyferrocene diblock copolymers: A route to organometallic nanospheres and nanowires.

摘要

Narrow polydispersed diblock copolymers containing either amorphous polyferrocenylphenylphosphine (PFP) or semicrystalline polyferrocenyldimethylsilane (PFDMS) segments were synthesized by sequential living anionic polymerization. These block copolymers form novel micellar aggregates in block selective solvents. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) were used to characterize these nanostructures. It was found that diblock copolymers with PFP blocks formed spherical micelles, as expected from the amorphous nature of the core-forming block. These spherical micellar structures could be further derivatized by using the reactive groups present in the aggregates. On the other hand, diblock copolymers with PFDMS segments formed either cylindrical or lamellar aggregates, depending on the block length of the corona-forming block. These results suggest that the interplay of the crystallization of the core-forming block and chain stretching of the corona-forming block is responsible for the micellar morphologies observed from semicrystalline diblock copolymers in dilute solution. It was also demonstrated that continuous ceramic nanolines on semiconducting substrates with lengths of micrometers and widths of as small as 8 nm could be fabricated by selective etching of cylindrical polyferrocenyldimethylsilane block copolymer micelles.