Polymer inclusion membranes as substrates for controlled in-situ gold nanoparticle synthesis

Poly(vinyl chloride) (PVC)-based polymer inclusion membranes (PIMs) containing the commercial anionic extractant Aliquat 336 and in some cases also 1-dodecanol as plasticizer were used for the fabrication of PIM surface-confined Au nanoparticles (NPs) by reduction of Au(III), extracted into the membranes as the [AuCl4](-) complex. The experimental conditions controlling Au NP size and distribution were studied using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The former technique showed unique NP distributions dependent on the reducing agent used while XRD data were found to be consistent with those obtained by wideangle X-ray scattering (WAXS) and revealed that the Au crystallite size decreased when the reduction temperature, reduction time, or reducing agent strength were increased. Conditions for producing PIM supported Au NPs that could be appropriate for chemical sensing or catalytic applications and with an acceptable thermal stability, based on thermogravimetric analysis (TGA) measurements, were established. Loaded to saturation with Au(III) PVC -based PIMs containing 20 wt% Aliquat 336 and 10 wt% 1-dodecanol were found to be suitable for producing dense Au NP layers which could be appropriate for catalytic applications. Partially loaded with Au(III) PVC -based PIMs without a plasticizer and containing 30 wt% Aliquat 336 allowed the fabrication of discrete disperse Au NPs on the membrane surface which could be expected to be suitable for sensing applications. This study demonstrates that PIMs are attractive low-cost substrates for the synthesis and immobilization of Au NPs of controlled size, density and shape which can potentially be used in catalytic and chemical sensing applications.