Diblock Copolymers with Amorphous Atactic Polyferrocenylsilane Blocks: Synthesis, Characterization, and Self-Assembly of Polystyrene-b lock-poly (ferrocenylethylmethylsilane) in the Bulk State
Living anionic ring-opening (ROP) polymerization of ethylmethylsilaferrocenophane yields atactic poly(ferrocenylethylmethylsilane) (PFEMS) homopolymers with controlled molecular weights (Mn = 4000−41 400) and narrow molecular weight distributions (PDI = 1.01−1.02). A series of well-defined polystyrene-block-poly(ferrocenylethylmethylsilane) (PS-b-PFEMS) diblock copolymers was synthesized from styrene and ethylmethylsilaferrocenophane via sequential anionic polymerization. The iron content was readily varied (PFEMS volume fraction = 0.07−0.68), affording high molecular weight (Mn = 38 700−149 000) iron-rich diblock copolymers with narrow molecular weight distributions (PDI = 1.00−1.07). Both the PFEMS homopolymers and the PS-b-PFEMS diblock copolymers were shown to be amorphous due to the atactic nature of the organometallic block. As a result, PS-b-PFEMS block copolymers readily undergo solid-state self-assembly in the bulk. A spectrum of nanometer-sized iron-rich morphologies has been accessed, and in many cases these arrays were found to be well-ordered over large areas.