Of these different surfactants, the tri-chain aromatic surfactant TC3Ph3 (sodium 1,5-dioxo-1,5-bis(3-phenylpropoxy)-3-((3phenylpropoxy)carbonyl) pentane-2-sulfonate) was shown to be highly graphene-compatible (nanocomposite electrical conductivity = 2.22 × 10 S cm), demonstrating enhanced electrical conductivity over nine orders of magnitude higher than neat natural rubber-latex matrix (1.51 × 10 S cm). Varying the number of aromatic moieties in the surfactants appears to cause significant differences to the final properties of the nanocomposites.

Here is presented a systematic study of the dispersibility of multiwall carbon nanotubes (MWCNTs) in natural rubber latex (NR-latex) assisted by a series of single-, double-, and triple-sulfosuccinate anionic surfactants containing phenyl ring moieties. Optical polarising microscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Raman spectroscopy have been performed to obtain the dispersion-level profiles of the MWCNTs in the nanocomposites. Interestingly, a triple-chain, phenyl-containing surfactant, namely sodium 1,5-dioxo-1,5-bis(3-phenylpropoxy)-3-((3-phenylpropoxy)carbonyl) pentane-2-sulfonate (TCPh), has a greater capacity the stabilisation of MWCNTs than a commercially available single-chain sodium dodecylbenzenesulfonate (SDBS) surfactant. TCPh provides significant enhancements in the electrical conductivity of nanocomposites, up to ∼10(-2) S cm(-1), as measured by a four-point probe instrument. These results have allowed compilation of a road map for the design of surfactant architectures capable of providing the homogeneous dispersion of MWCNTs required for the next generation of polymer-carbon-nanotube materials, specifically those used in aerospace technology.

Graphene is the newest member of the carbon family, and has revolutionized materials science especially in the field of polymer nanocomposites. However, agglomeration and uniform dispersion remains an Achilles" heel (even an elephant in the room), hampering the optimization of this material for practical applications. Chemical functionalization of graphene can overcome these hurdles but is often rather disruptive to the extended piconjugation, altering the desired physical and electronic properties. Employing surfactants as stabilizing agents in latex technology circumvents the need for chemical modification allowing for the formation of nanocomposites with retained graphene properties. This article reviews the recent progress in the use of surfactants and polymers to prepare graphene/polymer nanocomposites via latex technology. Of special interest here are surfactant structure-performance relationships, as well as background on the roles surfactantgraphene interactions for promoting stabilization.

The article addresses an interesting issue in the development of hybrid surfactants for waterin-CO2 (w/c) microemulsion stabilisation: the role of surfactant headgroup on the surfactant performance. The synthetic procedure, aqueous properties, and phase behaviour of a new hybrid sulfoglutarate surfactant are described. The compound resembles sulfosuccinate surfactants, commonly used to stabilize w/c phases, but with an extra methylene group incorporated into the hydrophilic headgroup. For comparison purposes, the related hydrocarbon (AOT14 and AOT14GLU) and fluorocarbon (di-CF2 and di-CF2GLU) surfactants are used to form w/c microemulsions. In general, the aqueous properties and w/c phase stability of both sulfoglutarates and sulfosuccinates are found to be similar, which shows the secondary role of the hydrophilic headgroup. Interestingly, the newly synthesised hybrid CF2/AOT14GLU (sodium (4H,4H,5H,5H,5H-pentafluoropentyl-2,2-dimethyl-1-propyl)-2-sulfoglutarate) proved to be more efficient than the normal sulfosuccinate, hybrid CF2/AOT14 (Ptrans = 383 bar, γcmc = 26.8 mN m -1 ) in terms of the aqueous behaviour and w/c phase stability.Switching to the sulfoglutarate compound, hybrid CF2/AOT14GLU (Ptrans = 232 bar, γcmc = 20.6 mN m -1 ) more effectively decreases the air-water surface tension by about ~ 5 mN m -1 as compared to the sulfosuccinate. High-pressure phase behaviour studies show significant improvements in stabilising w/c microemulsions at much lower cloud pressures. The results indicate distinct effects of the headgroup structure on the phase behaviour and physicochemical properties, particularly for this hybrid surfactant.

Citation: T Ardyani et al. "Surfactants with aromatic headgroups for optimizing properties of graphene/natural rubber latex composites (NRL): Surfactants with aromatic amine polar heads.

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. that microemulsions droplets had a rod-like morphology with a radius commensurate with the surfactant tail length and an aspect ratio between 6 and 35. In the presence of a large magnetic field (6.7 T) no reorientation of the droplets was observed by SANS.

A facile electrochemical exfoliation method was established to efficiently prepare conductive paper containing reduced graphene oxide (RGO) with the help of single chain anionic surfactant ionic liquids (SAILs). The surfactant ionic liquids are synthesized from conventional organic surfactant anions and a 1-butyl-3-methyl-imidazolium cation. For the first time the combination of SAILs and cellulose was used to directly exfoliate graphite. The ionic liquid 1-butyl-3-methyl-imidazolium dodecylbenzenesulfonate (BMIM-DBS) was shown to have notable affinity for graphene, demonstrating improved electrical properties of the conductive cellulose paper. The presence of BMIM-DBS in the system promotes five orders of magnitude enhancement of the paper electrical conductivity (2.71 × 10 S cm) compared to the native cellulose (1.97 × 10 S cm). A thorough investigation using electron microscopy and Raman spectroscopy highlights the presence of uniform graphene incorporated inside the matrices. Studies into aqueous aggregation behavior using small-angle neutron scattering (SANS) point to the ability of this compound to act as a bridge between graphene and cellulose, and is responsible for the enhanced exfoliation level and stabilization of the resulting dispersion. The simple and feasible process for producing conductive paper described here is attractive for the possibility of scaling-up this technique for mass production of conductive composites containing graphene or other layered materials.

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms AbstractThe article addresses the role of surfactant headgroup structure on hybrid surfactant performance for water-in-CO2 (w/c) microemulsion stabilisation. The synthetic procedure, aqueous properties, and phase behaviour of a new hybrid sulfoglutarate surfactant are described. The sulfoglutarate version has an extra methylene group incorporated into the hydrophilic headgroup. The related hydrocarbon (AOT14 and AOT14GLU) and fluorocarbon (di-CF2 and di-CF2GLU) surfactants were used to form w/c microemulsions. For these two groups, the aqueous properties and w/c phase stability of both sulfoglutarates and sulfosuccinates were found to be similar. The newly synthesized hybrid CF2/AOT14GLU (sodium (4H,4H,5H,5H,5H-pentafluoropentyl-2,2-dimethyl-1-propyl)-2-sulfoglutarate)proved to be more efficient than the normal sulfosuccinate, hybrid CF2/AOT14 in terms of the aqueous behaviour and w/c phase stability. Hybrid CF2/AOT14GLU more effectively decreased the air-water surface tension by ~ 2 mN m -1 and lowering the cloud pressures on CO2 by ~150 bar.