Organic-metalloblock copolymersvia photocontrolled living anionic ring-opening polymerization

Abstract

A new method for the preparation of organic-organometallic diblock copolymers including a polyferrocenylsilane (PFS) metalloblock through photocontrolled ring-opening polymerization (ROP) is reported. Polystyrene (PS) homopolymers end-capped with a cyclopentadienyl group (1) were used as macroinitiators for the photocontrolled ROP of sila[1]ferrocenophanes [Fe(η-C₅H₄)₂Si{C≡CtBu}₂] 3a and [Fe(η-C₅H₄)₂Si(Me)(C≡CSiMe₃)] 3b to afford diblock copolymers with controlled molecular weights and block ratios, as well as low polydispersities (PDI < 1.2). Block copolymer PS_m-b-[Fe(η-C₅H₄)₂Si{C≡C(t-Bu)}₂]_n4 was clusterized with [Co₂(CO)₈], forming the highly metallized PS_m-b-[Fe(η-C₅H₄)₂Si{Co₂(CO)₆C₂(t-Bu)}₂]_n (PS-bb-(Co-PFS), 7). The diblock PS_m-b-[Fe(η-C₅H₄)₂Si(Me)(C≡CH)]_n6 was prepared by selective desilylation of PS_m-b-[Fe(η-C₅H₄)₂Si(Me)(C≡CSiMe₃)]_n5 was then reacted with ClAuP(n-Bu)₃ in the presence of an amine as HCl acceptor to afford PS_m-b-[Fe(η-C₅H₄)₂Si(Me){C≡CAuP(n-Bu)₃}]_n (PS-bbb-(Au-PFS), 8). Preliminary studies on the self-assembly of these materials in thin films showed phase separation with metal-rich nanodomains within an organic matrix.