Phase Behavior of Alkyne-Functionalized Styrenic Block Copolymer/Cobalt Carbonyl Adducts and in Situ Formation of Magnetic Nanoparticles by Thermolysis

Abstract

A series of polystyrene-block-poly­(4-(phenyl­ethynyl)­styrene) (PS-b-PPES) diblock copolymers with a range of compositions were prepared by reversible addition–fragmentation chain transfer (RAFT) polymerization. Block copolymer/cobalt carbonyl adducts (PS x -PPES y [Co2(CO)6] n ) were subsequently prepared by reaction of Co2(CO)8 with the alkyne groups of the PPES block. Phase behavior of the block copolymer/cobalt carbonyl adducts (PS x -PPES y [Co2(CO)6] n , 8% ≤ wt % PS ≤ 68%) was studied by small-angle X-ray scattering and transmission electron microscopy (TEM). As the composition of PS x -PPES y [Co2(CO)6] n copolymers was shifted from PS as the majority block to PPES y [Co2(CO)6] n as the majority block, the morphology was observed to shift from lamellar with larger PS domains to cylindrical with PS as the minority component and then to spherical with PS as the minority component. These observations have been used to map out a partial phase diagram for PS x -PPES y [Co2(CO)6] n diblock copolymers. Heating of PS x -PPES y [Co2(CO)6] n samples at relatively low temperatures (120 °C) results in the formation of nanoparticles containing crystalline cobalt and cobalt oxide domains within the PPES y [Co2(CO)6] n regions as characterized by TEM, X-ray diffraction (XRD), and X-ray scattering.

Magnetic Hydrogels from Alkyne/Cobalt Carbonyl-Functionalized ABA Triblock Copolymers

“…Because the ultimate goal of this work was the preparation of hydrogels containing cobalt nanoparticles, a relatively high molecular weight PEO block (M n ≈ 35 kg/mol) was used as a constant center block and the alkyne-functionalized PPES block lengths were varied (n from 19 to 374) to enable coverage of a range of morphologies after addition of cobalt carbonyl. 8 were used in the reaction to maximize the extent of functionalization of the alkyne groups. 1 H NMR spectra of polymer/Co 2 (CO) 6 adducts showed slight peak broadening but no apparent change in peak areas when compared with 1 H NMR spectra of the corresponding triblock copolymers (Figure S8).…”

“…[12][13][14][15][16] Moreover, heating of such diblock copolymer assemblies at a mild temperature (120 °C) can lead to formation of crystalline cobalt/cobalt oxide nanoparticles within the organometallic domains. 8 Because the nanoparticle formation temperature is well below the decomposition temperature of most organic polymers, 17 the non-metallic block within such block copolymers is likely to retain its properties after heating and formation of nanoparticles. By designing similar block copolymers in which the organometallic block is combined with a block other than polystyrene, it should be possible to prepare a broad range of materials in which the properties of the cobalt nanoparticles are combined with those of the organic block.…”

Nanostructured Bimetallic Block Copolymers as Precursors to Magnetic FePt Nanoparticles

“…While the current work described in this manuscript was in progress, the formation of FeRu NPs for potential catalytic applications from the pyrolysis of a BCP containing Fe and Ru was described. 35 Cobalt-based nanomaterials have also been accessed using BCPs with cobalt-carbonyl clusters attached to ethynyl units [36][37][38] or half-sandwich cobaltocenium/ (η 5 -cyclopentadienyl)(η 4 -cyclobutadiene)cobalt moieties. 16,[39][40] Nanostructuring of the BCP through cylindrical domain formation has been shown to alter the magnetic properties of the resulting cobalt NPs.…”

Synthesis of PS-b-PPOA-b-PS triblock copolymer via sequential free radical polymerization and ATRP

“…Generally, block copolymers can be synthesized via two common strategies of sequential feeding and site transformation. The sequential feeding method means that block copolymer can be obtained by the sequential feeding of different monomers under the same kind of living polymerization mechanism such as anionic, cationic, group transfer, and living radical polymerization . The site transformation approach refers to synthesizing the block copolymers via different polymerization mechanisms, for which bi‐ and multifunctional initiators have been designed and prepared for attaining different polymerization mechanism demands of the monomers with different chemical structures .…”