PHYS01200704032 Debes Ray - Homi Bhabha National Institute

Absorbance
Chapter 4: Optimization of the Block Copolymer-mediated Synthesis of Gold Nanoparticles
(b)
2.0
1.6
1.2
2 wt% P85
2 wt% P85 + 0.002 wt% HAuCl4.3H2O
2 wt% P85 + 0.004 wt% HAuCl4.3H2O
2 wt% P85 + 0.006 wt% HAuCl4.3H2O
2 wt% P85 + 0.008 wt% HAuCl4.3H2O
2 wt% P85 + 0.01 wt% HAuCl4.3H2O
2 wt% P85 + 0.012 wt% HAuCl4.3H2O
2 wt% P85 + 0.014 wt% HAuCl4.3H2O
2 wt% P85 + 0.016 wt% HAuCl4.3H2O
2 wt% P85 + 0.018 wt% HAuCl4.3H2O
2 wt% P85 + 0.02 wt% HAuCl4.3H2O
0.8
0.4
0.0
200 400 600 800 1000
Wavelength (nm)
Figure 4.8. UV-visible spectra of (a) 0.5 wt% and (b) 2 wt% P85 with varying HAuCl 4 .3H 2 O
concentration.
The dependence of block copolymer concentration on the synthesis of gold nanoparticles has
been examined for different block copolymer concentration with varying the gold salt
concentration [192-194]. Figure 4.8 shows the UV-visible absorption spectra for 0.5 wt%
and 2 wt% P85 to compare with that of 1 wt% P85 as a function of gold salt concentration.
The effect of varying gold salt on the yield of synthesis shows the same trend for all block
copolymer concentrations as shown in Figure 4.2. However, the concentration of gold salt at
which the yield is the maximum has been found to be increasing with the block copolymer
concentration. Figure 4.9 show the UV-visible spectra with maximum absorbance of 0.5, 1
and 2 wt% P85 as obtained for 0.004, 0.008 and 0.016 wt% HAuCl 4 .3H 2 O, respectively. This
suggests that block copolymer concentration can be used to enhance the yield.
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