Sulfur-Functionalized Graphenes as Macro-Chain-Transfer and RAFT Agents for Producing Graphene Polymer Brushes and Polystyrene Nanocomposites

Abstract

Novel families of polystyrene carbon nanocomposites and graphene brushes were prepared by means of free radical styrene grafting using sulfur-functionalized graphene (S-FG) as macro-chain-transfer agent. Two strategies were examined for growing polystyrene chains onto graphite oxide (GO), stearylamine-modified GO (Stearyl-GO), and thermally reduced GO (TRGO): (i) chain transfer with novel thiolfunctionalized graphenes and (ii) RAFT-mediated polymerization using dithiourethane-, dithioester-and dithiocarbonate-functionalized graphenes. Novel thiol-functionalized graphenes were obtained from FG either by esterification with 3-mercaptopropionic acid or by reaction with propylene sulfide. The styrene graft polymerization was initiated either with AIBN at 65 °C or by thermal styrene self-initiation at 130 °C. The graphene content, varying between 0 and 5.2 wt %, was determined by means of thermogravimetric analysis (TGA). Upon hydrolytic cleavage of the dithiocarbonate linker, the stability of the S-FG dispersion in polystyrene was lost, and the nonbonded S-FG was separated quantitatively from polystyrene by solvent extraction. During melt processing the graphene brushes self-assembled to produce nanoribbons and skeleton-like carbon superstructures, as determined by means of transmission electron microscopy (TEM). Both grafting effectiveness and superstructure formation were monitored by means of melt rheology.

The “Grafting‐to” of Well‐Defined Polystyrene on Graphene Oxide via Nitroxide‐Mediated Polymerization

“…Using a combination of atom transfer nitroxide radical coupling chemistry with the “grafting onto” strategy, Deng et al reported an efficient way to functionalize the GO surface with presynthesized polymers. Sulfur‐functionalized graphenes were used as macrochain‐transfer and RAFT agents for producing G polymer brushes and PS NCs …”

Hybrid materials of platinum nanoparticles and thiol-functionalized graphene derivatives

“…The synthesis of the thiol-functionalized TRGO was carried out according to our recently published procedure [36]. TRGO (2.0 g) was dispersed in toluene (200 mL) by means of high pressure homogenization (1500 bar).…”

Nitrogen‐Doped Multilayer Graphene as Functional Filler for Carbon/Polyamide 12 Nanocomposites

“…Owing to the presence of functional groups, both dispersion and interfacial adhesion of graphene fillers are substantially improved. For instance, functionalized graphene was incorporated into polyethylene, polypropylene, polyurethanes, rubber, polystyrene, and polyamide . In contrast to micronized graphite and graphene nanoplatelets containing a large number of stacked graphene layers, single and few‐layer graphenes afford far superior mechanical, electrical, and thermal properties of the corresponding graphene/polymer nanocomposites.…”