Anionic Ring‐Opening Polymerization of a Germanium‐Bridged [1]Ferrocenophane: Synthesis and Morphology of Well‐Defined Polyferrocenylgermane Homopolymers and Block Copolymers

Abstract Well‐defined poly(ferrocenyldimethylgermane) homopolymers PFDMG [ $\overline M _{\rm n} $ = 18 800–33 700, degree of polymerization ( $\overline {DP} _{\rm n} $ ) = 66–117, polydispersity index (PDI) = 1.02–1.05] and polyisoprene‐ block ‐poly(ferrocenyldimethylgermane) diblock copolymers (PI x ‐ b ‐PFDMG y , for 6 , x / y = 359:23, volume fraction, ϕ PFDMG = 0.14, PDI = 1.04; for 7 , x / y = 337:56, ϕ PFDMG = 0.29, PDI = 1.04) have been prepared by anionic ring‐opening polymerization. The polymer morphology and thermal transition behaviour of PFDMG 5 ( $\overline M _{\rm n} $ = 18 800, $\overline {DP} _{\rm n} $ = 66, PDI = 1.02) have been investigated by wide‐angle X‐ray scattering (WAXS) and differential scanning calorimetry (DSC), respectively. Both studies suggest that PFDMG 5 possesses similar crystallization behaviour to its Group 14 analogue, poly(ferrocenyldimethylsilane). Transmission electron microscopy (TEM) images of the solid state thin films of the diblock copolymers 6 ( ϕ PFDMG = 0.14) and 7 ( ϕ PFDMG = 0.29) show microphase separated structures of spherical or cylindrical PFDMG domains in a PI matrix respectively. Furthermore, these morphologies can be preserved after selective plasma etching of the PI block. magnified image