CO2-responsive TX-100 emulsion for selective synthesis of 1D or 3D gold

The effect of CO2 on the properties of water/poly(oxyethylene)iso-octylphenyl ether (TX-100)/isooctane emulsions was investigated by direct observation, small angle X-ray scattering (SAXS), and UV-vis spectroscopy at 303.2 K in the pressure range 0-5 MPa. It was demonstrated that the droplet size of the emulsion was sensitive to the pressure of CO2, and the droplet size can be tuned in a wide range from the micron to the nanometre scale. When the CO2 pressure was 3.90 MPa, the droplet size reached a minimum value of 92 nm. To demonstrate the utilization of the CO2-responsive water/TX-100/isooctane emulsion, gold particles were synthesized using HAuCl4 as a gold precursor and TX-100 as a reducing reagent. It was shown that gold particles with different morphologies, such as nanowires, nanorods, and polyhedral nanocrystals could be synthesized by controlling the pressure of CO2.