PHYS01200704032 Debes Ray - Homi Bhabha National Institute

d/d (cm -1 )
Chapter 4: Optimization of the Block Copolymer-mediated Synthesis of Gold Nanoparticles
10
1
0.5 wt% P85
1 wt% P85
2 wt% P85
0.5 wt% P85 + 0.004 wt% HAuCl4.3H2O
1 wt% P85 + 0.008 wt% HAuCl4.3H2O
2 wt% P85 + 0.016 wt% HAuCl4.3H2O
0.1
0.01
0.1
Q (Å -1 )
Figure 4.14. SANS data of 0.5, 1 and 2 wt% P85 without and with the addition of gold salt
concentrations of the corresponding maximum yield of nanoparticles. The hollow and filled
symbols represent data of P85 without and with gold salt, respectively.
Figure 4.15(a) shows TEM images of gold nanoparticles as obtained from 2 wt% P85
+ 0.016 wt% HAuCl 4 .3H 2 O systems. The size distribution of the nanoparticles is obtained by
considering such large number of images and is shown in Figure 4.15(b). The nanoparticles
have a mean size of about 20 nm. The average size of the gold nanoparticles in this system
when compared with 1 wt% P85 + 0.008 wt% HAuCl 4 .3H 2 O (Figure 4.4) is found to increase
with block copolymer concentration. This increase in size is consistent with the broadening of
the UV-visible spectra for gold nanoparticles sample at higher block copolymer concentration
(Figure 4.9). It has been observed that increase in the block copolymer concentration
increases the yield of gold nanoparticles which is related to availability of more number of
micelles to enhance the probability of nucleation and growth of the nanoparticles (Table 4.1).
Unfortunately, the increase in concentration also leads to large size of the gold nanoparticles,
104