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Issue 31, 2016
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Hydrophobic matrix-free graphene-oxide composites with isotropic and nematic states

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Abstract

We demonstrate a novel route to synthesise hydrophobic matrix-free composites of polymer-grafted graphene oxide (GO) showing isotropic or nematic alignment and shape-memory effects. For the first time, a cationic macroinitiator (MI) has been immobilised on anionic GO and subsequently grafted with hydrophobic polymer grafts. Dense grafts of PBA, PBMA and PMMA with a wide range of average graft lengths (MW: 1–440 kDa) were polymerised by surface-initiated controlled radical precipitation polymerisation from the statistical MI. The surface modification is designed similarly to bimodal graft systems, where the cationic MI generates nanoparticle repulsion, similar to dense short grafts, while the long grafts offer miscibility in non-polar environments and cohesion. The state-of-the-art dispersions of grafted GO were in the isotropic state. Transparent and translucent matrix-free GO-composites could be melt-processed directly using only grafted GO. After processing, birefringence due to nematic alignment of grafted GO was observed as a single giant Maltese cross, 3.4 cm across. Permeability models for composites containing aligned 2D-fillers were developed, which were compared with the experimental oxygen permeability data and found to be consistent with isotropic or nematic states. The storage modulus of the matrix-free GO-composites increased with GO content (50% increase at 0.67 wt%), while the significant increases in the thermal stability (up to 130 °C) and the glass transition temperature (up to 17 °C) were dependent on graft length. The tuneable matrix-free GO-composites with rapid thermo-responsive shape-memory effects are promising candidates for a vast range of applications, especially selective membranes and sensors.

Graphical abstract: Hydrophobic matrix-free graphene-oxide composites with isotropic and nematic states

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Publication details

The article was received on 22 Feb 2016, accepted on 17 May 2016 and first published on 18 May 2016


Article type: Paper
DOI: 10.1039/C6NR01502F
Citation: Nanoscale, 2016,8, 14730-14745
  • Open access: Creative Commons BY-NC license
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    Hydrophobic matrix-free graphene-oxide composites with isotropic and nematic states

    M. Wåhlander, F. Nilsson, A. Carlmark, U. W. Gedde, S. Edmondson and E. Malmström, Nanoscale, 2016, 8, 14730
    DOI: 10.1039/C6NR01502F

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