reduction makes it possible to prepare NPs from many metal ions (not only those of
noble metals). The synthesis of copper NPs having a metal lattice is an illustrative
example of the advantages of the radiation–chemical method, whereas chemical
reduction, as a rule, leads to formation of copper protoxide [121].
Reduction or precipitation of metal ions is commonly applied for preparation of
inorganic NPs by so-called intermatrix synthesis [81–85, 103–106, 113–117,
123–127] in polyelectrolyte matrices. Stabilization of inorganic NPs in polymeric
matrices prevents their aggregation and, in addition, allows control of their growth
rate and size. Polyelectrolytes or ion-exchange resins, which are filled by metal
ions, are widely used precursors for fabrication of nanocomposites. The intermatrix
synthesis technique has proved to be applicable for preparation of catalytically,
electrocatalytically, and magnetically active composites with zero-valent metals
(e.g., Cu, Pd, Ag, and others) via a chemical reduction of metal ions in matrices of
cation-exchange resins. Due to the fact that functional groups of the polymeric
component appear to be regenerated after each cycle (converted back into their
initial ionic form), undertaking consecutive cycles with other metals will result in
the formation of NPs with advanced structures (e.g., bimetallic core–shell, trimetallic core–sandwich, etc.) [116, 117]. A precipitation of metal ions opens the
possibility to obtain nanocomposites on the basis of metal sulfide NPs [104, 116].
The advantages of synthesis of metal NPs in multilayer systems and their development are discussed in [103]. A number of studies [82–84, 104–106, 125–127]
demonstrate that the LbL deposition of polyelectrolytes containing metal ions and
subsequent reduction of these metal ions provides a straightforward technique for
obtaining encapsulated NPs with a controlled size. Encapsulation into polymers
appears to be advantageous because, apart from stabilization and protection of NPs,
polymers offer unique possibilities for both a modification of the environment around
catalytic sites and a change of access to these sites [103]. Various polyelectrolytes
and metal ions with different binding activities can be used for assembling LbL-based
hybrids, which are precursors for polymer–inorganic composites. Control of the
precursor structure through conditions for a buildup of the LbL films and regimes
of metal ion reduction provide prerequisites for the development of composites
containing NPs with various sizes and even with different spatial distributions of
NPs [105, 106]. The PAA/PEI films with silver NPs exhibit electrocatalytic behavior
and antibacterial activity [106]. Palladium–nickel bimetallic core–shell NPs with
magnetic properties were obtained by chemical reduction in the PAA/PAH films
[123]. Through a chemical reduction, palladium NPs with a diameter of 2 nm were
obtained as seeds for further growth of Ni
2þ shells, with control of their thicknesses
(Fig. 17).
The LbL technique is widely applied for assembly of preformed NPs with
oppositely charged polyelectrolytes [128–131]. The metal or semiconductor NPs
of appropriate sizes in stabilizing media should be prepared before assembly of the
LbL films. However, it appears to be quite difficult to realize an effective control
over the concentration of NPs [103].
During the last few years, progress has been made in preparation of
polymer–inorganic composites based on the LbL films, mainly related to membrane
catalytic systems (Fig. 18). The LbL adsorption in porous polymeric membranes
206
D.V. Pergushov et al.
noble metals). The synthesis of copper NPs having a metal lattice is an illustrative
example of the advantages of the radiation–chemical method, whereas chemical
reduction, as a rule, leads to formation of copper protoxide [121].
Reduction or precipitation of metal ions is commonly applied for preparation of
inorganic NPs by so-called intermatrix synthesis [81–85, 103–106, 113–117,
123–127] in polyelectrolyte matrices. Stabilization of inorganic NPs in polymeric
matrices prevents their aggregation and, in addition, allows control of their growth
rate and size. Polyelectrolytes or ion-exchange resins, which are filled by metal
ions, are widely used precursors for fabrication of nanocomposites. The intermatrix
synthesis technique has proved to be applicable for preparation of catalytically,
electrocatalytically, and magnetically active composites with zero-valent metals
(e.g., Cu, Pd, Ag, and others) via a chemical reduction of metal ions in matrices of
cation-exchange resins. Due to the fact that functional groups of the polymeric
component appear to be regenerated after each cycle (converted back into their
initial ionic form), undertaking consecutive cycles with other metals will result in
the formation of NPs with advanced structures (e.g., bimetallic core–shell, trimetallic core–sandwich, etc.) [116, 117]. A precipitation of metal ions opens the
possibility to obtain nanocomposites on the basis of metal sulfide NPs [104, 116].
The advantages of synthesis of metal NPs in multilayer systems and their development are discussed in [103]. A number of studies [82–84, 104–106, 125–127]
demonstrate that the LbL deposition of polyelectrolytes containing metal ions and
subsequent reduction of these metal ions provides a straightforward technique for
obtaining encapsulated NPs with a controlled size. Encapsulation into polymers
appears to be advantageous because, apart from stabilization and protection of NPs,
polymers offer unique possibilities for both a modification of the environment around
catalytic sites and a change of access to these sites [103]. Various polyelectrolytes
and metal ions with different binding activities can be used for assembling LbL-based
hybrids, which are precursors for polymer–inorganic composites. Control of the
precursor structure through conditions for a buildup of the LbL films and regimes
of metal ion reduction provide prerequisites for the development of composites
containing NPs with various sizes and even with different spatial distributions of
NPs [105, 106]. The PAA/PEI films with silver NPs exhibit electrocatalytic behavior
and antibacterial activity [106]. Palladium–nickel bimetallic core–shell NPs with
magnetic properties were obtained by chemical reduction in the PAA/PAH films
[123]. Through a chemical reduction, palladium NPs with a diameter of 2 nm were
obtained as seeds for further growth of Ni
2þ shells, with control of their thicknesses
(Fig. 17).
The LbL technique is widely applied for assembly of preformed NPs with
oppositely charged polyelectrolytes [128–131]. The metal or semiconductor NPs
of appropriate sizes in stabilizing media should be prepared before assembly of the
LbL films. However, it appears to be quite difficult to realize an effective control
over the concentration of NPs [103].
During the last few years, progress has been made in preparation of
polymer–inorganic composites based on the LbL films, mainly related to membrane
catalytic systems (Fig. 18). The LbL adsorption in porous polymeric membranes
206
D.V. Pergushov et al.