Modified Natural Rubber Induced Aqueous to Toluene Phase Transfer of Gold and Platinum Colloids

Citrate‐stabilized gold and platinum particles were prepared in aqueous phase and transferred to toluene phase by employing 2‐propanol as the transfer agent. It was found that the modified natural rubber (ENR) induced the phase transfer and assisted the dispersion of the citrate‐free metal particles into the organic phase. The amounts of gold and platinum transferred are 93.4% and 86.1%, respectively. This phase transfer technique produced organosols of smaller particle sizes and narrower size distribution with self‐assembly arrangements when compared to those prepared via the previous in situ preparations. The respective average particle size and standard deviation of gold before and after phase transfer were 6.3 ± 1.7 nm and 7.2 ± 1.3 nm, while for platinum they were 4.0 ± 0.7 nm and 4.2 ± 0.8 nm. The slight increase in the average sizes and overall size distributions in both metals after transfer was attributed to multiparticle aggregation in the organic phase.