Influence of TX-100 on the size controlled synthesis of gold colloid

Gold colloids were synthesized via mixing the aqueous solution of HAuCl₄ and Triton X-100 at room temperature. The gold sol samples were quickly obtained during first 2 h then the samples were placed for 8 h to ensure they were completely stable. The colour of most samples turned to violet red. But the sample with 0.5 ml TX-100 remained colorless. During synthesizing, UV-vis absorption spectra were recorded every 10 s. By studying the synthesis time-dependent surface plasmon resonance (SPR), we found that the growth of gold colloids presented an exponential increase form. By analyzing the TX-100 concentration dependence of absorption peak, the effect of TX-100 concentration on gold colloid diameter was studied and the gold colloid's final dimension was resulted from competition between reducing speed and coating speed.