Modification of surfactant chemical structure for graphene/biopolymer conductive nanocomposites
This research aimed to modify and examine the role of new graphene-compatiblesurfactants and the mechanism in the stabilisation of graphene incorporated intobiopolymer matrix namely natural rubber latex (NRL) and cellulose for thepreparation of conductive nanocomposites. The surfactants were systema...
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| Format: | thesis |
| Language: | eng |
| Published: |
2019
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| Subjects: | |
| Online Access: | https://ir.upsi.edu.my/detailsg.php?det=5363 |
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| Summary: | This research aimed to modify and examine the role of new graphene-compatiblesurfactants and the mechanism in the stabilisation of graphene incorporated intobiopolymer matrix namely natural rubber latex (NRL) and cellulose for thepreparation of conductive nanocomposites. The surfactants were systematicallydesigned and synthesised to have enhanced compatibility with graphene as compared to commerciallyavailable common surfactants. The modifications are centred on variation of surfactantchain degree as well as aromatic numbers on surfactant tail, aromatisation on surfactantheadgroup, ion exchange of hydrophilic headgroup, and metal incorporation on surfactantheadgroup. The graphene-compatible surfactants have been investigated by a range oftechniques including proton nuclear magnetic resonance (H NMR) spectroscopy, air water(a/w) surface tension measurement, and zeta potential measurement. The performance of thesynthesised surfactants for the dispersion of graphene in biopolymer was studied by fieldemission scanning electron microscopy (FESEM), high-resolution transmission electronmicroscopy (HRTEM), Raman spectroscopy, and atomic force microscopy (AFM). The electricalconductivities of the nanocomposites were also measured using four point probemeasurement. The aggregated structures of surfactants in aqueous phase and in graphenedispersion were examined using small-angle neutron scattering (SANS) analysis. Researchfinding showed that aromatisation is a crucial factor influencing surfactant compatibility withgraphene surfaces where the intensity is enhanced with increasing the number of aromaticgroups on surfactant molecular structure. The synthesised surfactants exhibit more uniformdispersion of graphene compared to commercial surfactants used in this study. Thehighest electrical conductivity achieved for nanocomposite with NRL was 1.08 x 10? S cm?while for cellulose was2.71 x 10?? S cm?. Analysis using SANS showed that the most efficient surfactants for bothnanocomposites exhibited micelle shape similar with graphene which are stacked-disk andlayered structure. In conclusion, the presence of higher aromatic groups in thesurfactant structure gives rise to relative graphene-compatibility and thus thenanocomposites final properties. In implication, the results obtained are beneficial forthe development efficient surfactants for carbon nanomaterial and low-dimensional nanomaterial based technology. |
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