PHYS01200704032 Debes Ray - Homi Bhabha National Institute

Chapter 6: High-Yield Synthesis of Gold Nanoparticles
temperature does not show significant variation in their profile with respect to that of pure
block copolymer solution suggests that most of the block copolymers remain free as micelles
in gold nanoparticles solution. We have fitted these free block copolymers coexisting as
micelles and unimers. The scattering from block copolymer micelles is calculated using coreshell
particles with different scattering length densities for the core and shell. The structure of
these micelles is described by a model consisting of non-interacting Gaussian PEO chains
attached to the surface of the PPO core. The scattering from individual block copolymer
unimer is calculated by the Gaussian chain conformation. The fitted parameters are given in
Table 6.2. The fraction of block copolymer that forms micelles increases as a result of
enhanced micellization (salting out effect) with the increase in the gold salt concentration.
The micellar size is found to be almost similar having core radius of 4.0 nm surrounded by a
PEO chain of radius of gyration of 1.2 nm and aggregation number around 70. The radius of
gyration of unimer is found to be 2.3 nm. The schematic of gold nanoparticle is shown in
Figure 6.10.
Figure 6.10. Schematic of structure of block copolymer-stabilized gold nanoparticles. The
samples in cells show that the concentration of gold nanoparticles in presence of additional
reductant can be enhanced.
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