Multifunctional Block Copolymer: Where Polymetallic and Polyelectrolyte Blocks Meet

Sequential reversible addition–fragmentation transfer (RAFT) polymerization of a mixed sandwich cobaltocene monomer (η⁵-cyclopentadienyl-cobalt-η⁴-cyclobutadiene (CpCoCb)) and a phosphonium salt functionalized styrene monomer resulted in the first example of a unique multifunctional block copolymer consisting of a metallopolymer block and a polyelectrolyte block. The polyelectrolyte block was decorated with a gold anion (AuCl₄^–) via salt metathesis, resulting in a heterobimetallic block copolymer with distinct gold and cobalt sections. Solution self-assembly behavior of this unique metallopolymer-<i>b</i>-polyelectrolyte copolymer before and after salt metathesis was studied. Heterobimetallic micelles with a gold containing core and a cobalt-containing corona were obtained, and then the core was reduced to form gold nanoparticles (AuNPs). Studies on the solid-state self-assembly of this unique block copolymer showed that it phase separated into hexagonally packed cylinders. Salt metathesis of the phase-separated block copolymers was utilized as the first example of a nonstandard selective staining method to exclusively stain the polyelectrolyte domains with the AuCl₄^– anion. Staining the metallopolymer domain by RuO₄ provided the complementary pattern. Pyrolysis of the self-assembled block copolymers resulted in magnetic cobalt-phosphate nanoparticles with 17% char yield

Hierarchical Templating of a BiFeO₃–CoFe₂O₄ Multiferroic Nanocomposite by a Triblock Terpolymer Film

A process route to fabricate templated BiFeO₃/CoFe₂O₄ (BFO/CFO) vertical nanocomposites is presented in which the self-assembly of the BFO/CFO is guided using a self-assembled triblock terpolymer. A linear triblock terpolymer was selected instead of a diblock copolymer in order to produce a square-symmetry template, which had a period of 44 nm. The triblock terpolymer pattern was transferred to a (001) Nb:SrTiO₃ substrate to produce pits that formed preferential sites for the nucleation of CFO crystals, in contrast to the BFO, which wetted the flat regions of the substrate. The crystallographic orientation and magnetic properties of the templated BFO/CFO were characterized

Uniform, High Aspect Ratio Fiber-like Micelles and Block Co-micelles with a Crystalline π‑Conjugated Polythiophene Core by Self-Seeding

Monodisperse fiber-like micelles with a crystalline π-conjugated poly­thiophene core with lengths up to ca. 700 nm were successfully prepared from the diblock co­polymer poly­(3-hexyl­thiophene)-<i>block</i>-poly­styrene using a one-dimensional self-seeding technique. Addition of a poly­thiophene block co­polymer with a different corona-forming block to the resulting nanofibers led to the formation of segmented B-A-B triblock co-micelles by crystallization-driven seeded growth. The key to these advances appears to be the formation of a relatively defect-free crystalline micelle core under the self-seeding conditions