Nanopatterning and micropatterning of cobalt containing block copolymers via phase‐separation and lithographic techniques

Abstract

Reversible addition fragmentation transfer (RAFT) agent functionalized polydimethylsiloxane (PDMS-RAFT) was used as a macro-RAFT agent to polymerize a mixed sandwich cobaltocene containing monomer featuring g 5 -cyclopentadienyl-cobalt-g 4 -cyclobutadiene. High molecular weight block copolymers (BCP) consisting of a metallic block and a PDMS block with excellent control over molecular weight and polydispersity were prepared. Solid-state self-assembly of this BCP resulted in hexagonal domains of metallopolymer phaseseparated from PDMS. In solution, spherical micelles with a metallic core, stabilized by a PDMS corona were prepared. Pyrolysis of the BCP resulted in magnetic nanoparticles with 30% char yield. The BCP was used as an ink material for microcontact printing (lCP) to transfer long-ranged patterns.

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

“…Among the reported methods for the preparation of polymer−metal hybrids, 6,50−52 direct polymerization of metalcontaining monomers, 35,38,45,53 direct mixing of polymers and nanoparticles, 54,55 and in situ formation of metallic particles from polymer−metal complexes 56,57 have all been proven to be successful. For example, Cohen and co-workers have reported the synthesis of multiple types of nanoparticles within specific domains of polystyrene-block-polyvinylpyridine (PS−PVP) block copolymer templates through thermolysis of organometallic complexes coordinated to the PVP block.…”

“…As increasing computational needs require devices with greater storage density, new methods for the manipulation of magnetic particles at shorter length scales (∼10 nm) are needed. − Block copolymers, which can phase separate and self-assemble into ordered structures on the 10–100 nm length scale, − have attracted much research interest as vehicles for the ordering of magnetic particles. ,, If one or more blocks in a block copolymer are ligand-functionalized, the block copolymers have the potential to stabilize, locate, and organize metallic species (including nanoparticles and their precursors) within the ordered nanometer-scale domains. − For example, iron oxide nanodots have been arranged into hexagonal arrays through self-assembly of polystyrene- block -poly­(ethylene oxide) diblock copolymers . Thermolysis of cobalt-, iron-, and nickel-containing precursors within diblock copolymer matrices has yielded ordered arrays of magnetic nanoparticles. ,− Hybrid materials based upon biocompatible copolymers and metal species are also of great interest in the development of vehicles for bioimaging or drug delivery. − For example, encapsulation of magnetic nanoparticles within polymer micelles provides a method for using magnetic fields to control release of encapsulated drugs .…”

“…Among the reported methods for the preparation of polymer–metal hybrids, ,− direct polymerization of metal-containing monomers, ,,, direct mixing of polymers and nanoparticles, , and in situ formation of metallic particles from polymer–metal complexes , have all been proven to be successful. For example, Cohen and co-workers have reported the synthesis of multiple types of nanoparticles within specific domains of polystyrene- block -polyvinylpyridine (PS–PVP) block copolymer templates through thermolysis of organometallic complexes coordinated to the PVP block. , Previously, our group has shown that polystyrene- block -poly­(4-(phenyl­ethynyl)­styrene) diblock copolymers (PS x -PPES y ), in which the two blocks are relatively miscible because of their similar monomer structures, phase separate after the selective addition of cobalt carbonyl to the alkyne groups of the PPES block. , Thermolysis of these organometallic polymers at moderate temperatures (110–120 °C) results in the formation of cobalt nanoparticles within the PPES domains of the polymer matrix.…”

Simple Benchtop Approach to Polymer Brush Nanostructures Using Visible-Light-Mediated Metal-Free Atom Transfer Radical Polymerization

“…Recently, methods such as surface-initiated electrochemical ATRP ( e ATRP) − have been reported by several groups as versatile alternatives to traditional surface patterning procedures. While these techniques offer notable improvements in the field, they also pose certain challenges, including delayed response time for complete deactivation, requirement for copper-based catalysts, and the lack of easy access to arbitrarily patterned surfaces …”

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 . Cobalt-based nanomaterials have also been accessed using BCPs with cobalt-carbonyl clusters attached to ethynyl units − or half-sandwich cobaltocenium/(η 5 -cyclopentadienyl)­(η 4 -cyclobutadiene)­cobalt moieties. ,, Nanostructuring of the BCP through cylindrical domain formation has been shown to alter the magnetic properties of the resulting cobalt NPs . In addition, Pd-pincer complexes have been introduced to poly­(styrene- b -2-vinylpyridine) (PS- b -P2VP) via either coordination or through stacking interactions leading to morphological transitions and the formation of disk-shaped Pd NP aggregates organized into ordered hierarchical arrays …”