Photocontrolled living anionic polymerization of phosphorus-bridged [l]ferrocenophanes: A route to well-defined polyferrocenylphosphine (PFP) homopolymers and block copolymers

Phosphorus-bridged strained [1]ferrocenophanes [Fe{(η-C5H4)2P(CH2CMe3))] (2) and [Fe((η-C5H4)2P(CH2SiMe3)]] (3) with neopentyl and (trimethylsilyl)methyl substituents on phosphorus, respectively, have been synthesized and characterized. Photocontrolled living anionic ring-opening polymerization (ROP) of the known phosphorus-bridged [l]ferrocenophane [Fe{(η-C5H4)2P(CMe3)}] (1) and the new monomers 2 and 3, initiated by Na[C5H5] in THF at 5°C, yielded welldefined polyferrocenylphosphines (PFPs), [Fe{(η-C5H4)2PR}]., (R=CMe3(4), CH2CMe3(5), and CH2SiMe3(6)), with controlled molecular weights (up to ca. 60x103Da) and narrow molecular weight distributions. The PFPs 4-6 were characterized by multinuclear NMR spectroscopy, DSC, and by GPC analysis of the corresponding poly(ferrocenylphosphine sulfides) obtained by sulfurization of the phosphorus(III) centers. The living nature of the photocontrolled anionic ROP allowed the synthesis of well-defined all-organometallic PFP-b-PFSF(7a and 7b) (PFSF= polyferrocenylmethyl(3,3,3,-trifluoropropyl)silane) diblock copolymers through sequential monomer addition. TEM studies of the thin films of the diblock copolymer 7 b showed microphase separation to form cylindrical PFSF domains in a PFP matrix. KGaA.