الفهرس 
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Abstract
The importance of nanomaterials for science and technology is highly increased in last years. Gold and silver nanoparticles had a
significant role in this process, due to their many peculiarities, first of all
the surface plasmon absorption and the surface accessibility for further
functionalization. This PhD thesis passes through the synthesis of gold
and silver nanoparticles within polymer matrix, with the final aim of
producing homogenous and monodistributed polymer/metal
nanocomposites. Our work was extended to studying structural and
optical properties of these nanostructures. Two novel pathways were
exploited for this purposes, the first one consists of UV-irradiation
synthesis of gold nanoparticles within PVA matrix and the second one
consists of polyol reduction synthesis of silver particles stabilized by
PVA/PVP. Both cases originated gold and silver particles with strong
absorption bands in the visible regions.
PVA/Au nanocomposites were fabricated with a photoreduction
method using UV-irradiation in presence of AgNO3. The irradiated
samples are compared with unirradiated ones to investigate the
mechanism of gold nanoparticle formation and the effect of UV
irradiation, AgNO3 and polymer matrix on the size of the particles. The
spherical gold nanoparticles were formed in polymer medium at a
specific UV exposure time. The particle size decreased when the silver
salt was increased. In this work, we have described a novel route for
preparation of PVA/Au nanocomposite using seed-mediated growth
under the UV irradiation. We set the aim of differentiating between the
two main phases of nanoparticle formation in solid homogeneous phase,
namely nucleation and growth. To this end, we first dissolve the gold and
silver salts within the polymer matrix to form metallopolymers films with
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well defined structures in which metal centers are embedded directly in
the polymer backbone.
In the second part of this work, Ag nanoparticles supported within
polyvinyl alcohol (PVA)/ polyvinyl pyrrolidone (PVP) films have been
successfully synthesized using novel in situ method. PVA and PVP acted
as stabilizer and polyol reductant, respectively. It was found that
PVA/PVP-stabilized silver nanocomposite film revealed the presence of
well-dispersed and spherical silver nanoparticles with average diameter of
30 nm, while the particle sizes were reduced as the PVP percentage
increased. Here new mechanism on formation of the silver nanoparticles
was proposed, quite different from that in the liquid-phase preparation.
As the metallo-polymer mixtures were casted, water evaporated first and
polymer molecules were then dried to form coils i.e. the polymeric films
act as physical barrier confining silver nitrate within their chains. Then,
the silver nitrate then reduced to silver, which nucleated and grew.
The samples were analysed using UV–Visible spectroscopy, X-ray
diffraction, Transmission Electron Microscopy and Fourier transform
infrared spectrometry.