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

Well-defined poly(ferrocenyldimethylgermane) homopolymers PFDMG [(M) over bar (n)=18 800-33 700, degree of polymerization ((DP) over bar (n))=66-117, polydispersity index (PDI)=1.02-1.05] and polyisoprene-block-poly(ferrocenyldimethylgermane) diblock copolymers (PIx-b-PFDMG(y), for 6, x/y=359:23, volume fraction, phi(PFDMG)=0.14, PDI=1.04; for 7, x/y=337:56, phi(PFDMG)=0.29, PDI =1.04) have been prepared by anionic ring-opening polymerization. The polymer morphology and thermal transition behaviour of PFDMG 5 ((M) over bar (n)=18 800, (DP) over bar (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 (phi(PFDMG)=0.14) and 7 (phi(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.