Preparation and self-assembly of polyferrocenyldimethylsilane-containing tri- and pentablock terpolymers

Abstract

Functional block copolymers (BCPs) featuring metal moieties are a unique class of materials because of their switching capabilities and pronounced microphase separation behaviour. Within this work, ABC and CBABC tri- and pentablock terpolymers consisting of polystyrene (PS), poly(1,1′-dimethylsilaferrocenophane) (PFS) and a third block segment C either consisting of poly(methyl methacrylate) (PMMA) or poly(2-vinylpyridine) (P2VP) were synthesized via sequential living anionic polymerization. Well-defined polymers having molar masses up to 90 kg mol−1 and low dispersity index values, Đ, below 1.10 were obtained. The multi-functional BCPs were characterized with respect to their constitution and composition by size-exclusion chromatography (SEC) measurements and NMR spectroscopy. Focus of this work was to study the microphase separation of the metal-containing tri- and pentablock terpolymers by (scanning) transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) measurements. Highly ordered structures at the nanoscale were observed comprising lamellar or cylindrical morphologies with more complex core-shell cylindrical morphologies for the organometallic block segment. This structure formation was more pronounced in case of P2VP-containing ABC terblock copolymers. Finally, synthetic approaches for the preparation of CBABC pentablock terpolymers were presented and the obtained bulk morphologies of these polymers were investigated by TEM and SAXS measurements.