1 Introduction
During recent decades, self-organization phenomena in macromolecular systems
based on synthetic polyelectrolytes, as well as in complex systems containing natural
macromolecules, have been extensively and successfully investigated. First of all,
the studies have been aimed at gaining deeper understanding of self-organization
mechanisms in biological systems. An example is the phenomenon of DNA compaction, which was revealed upon examination of the conformational behavior of
double-helix DNA complexed with cationic surfactants in nonpolar solvents such
as chloroform. The experimental results on such “null DNA,” whose charge is fully
compensated, under conditions pronouncedly different from those typical for common aqueous media, suggested that DNA compaction can be considered as intrinsic
property of an uncharged double helix. Experts both in physical chemistry of
polymers and in molecular biology have positively evaluated this concept [1–3].
Interpolyelectrolyte complexes (IPECs) resulting from coupling oppositely
charged (or getting charged) polyelectrolytes obviously take an important and significant part in a domain of self-organizing polymer systems. Such macromolecular
co-assemblies built up from linear polyions have attracted the attention of experts in
polymer science for a long time [4–9]. Nowadays, one can confidently relate IPECs
to smart and intelligent functional complex polymers having a pronounced tendency
toward self-organization. Also of interest is the response of IPECs to minor variations
in their environment (particularly to changes in pH, ionic strength, temperature, etc.)
via considerable conformational changes and the whole spectrum of their physicochemical and mechanical characteristics. The unique simplicity of preparation of
IPECs, together with an availability of linear polyelectrolytes, make such macromolecular co-assemblies and IPEC-based materials very promising for numerous
applications.
IPECs have been demonstrated to act as effective flocculants and surface
modifiers [10–13]. One can emphasize the successful application of IPECs as effective and available binders for soils and grounds in the aftermath of the accident in
the Chernobyl atomic power station (Ukraine).These macromolecular co-assemblies
were used to suppress erosion of soils and grounds and thus to prevent radionuclide
contamination caused by spreading of radioactive particles [10, 14]. Twenty-five
years later, IPECs have again attracted attention because of similar problems arising
from the accident in the Fukushima Daiichi atomic power station (Japan) [15, 16].
Another attractive application of IPECs is for medical purposes in the design of
pharmaceuticals for targeted drug delivery followed by controlled release, e.g., for a
nonviral gene delivery into cells [17, 18].
Nowadays, we clearly see that the domain of interpolyelectrolyte interactions
and IPECs is rapidly developing, involving relatively new areas of science and
opening new possibilities for application of these macromolecular co-assemblies.
With IPECs as templates, novel organic–inorganic complex systems and hybrid
nanocomposites based on these are successfully being developed. During the last
few years, studies on IPECs have been considerably extended as polyelectrolytes
with new (nonlinear) topologies have become available. This becomes possible due
Advanced Functional Structures Based on Interpolyelectrolyte Complexes
175
During recent decades, self-organization phenomena in macromolecular systems
based on synthetic polyelectrolytes, as well as in complex systems containing natural
macromolecules, have been extensively and successfully investigated. First of all,
the studies have been aimed at gaining deeper understanding of self-organization
mechanisms in biological systems. An example is the phenomenon of DNA compaction, which was revealed upon examination of the conformational behavior of
double-helix DNA complexed with cationic surfactants in nonpolar solvents such
as chloroform. The experimental results on such “null DNA,” whose charge is fully
compensated, under conditions pronouncedly different from those typical for common aqueous media, suggested that DNA compaction can be considered as intrinsic
property of an uncharged double helix. Experts both in physical chemistry of
polymers and in molecular biology have positively evaluated this concept [1–3].
Interpolyelectrolyte complexes (IPECs) resulting from coupling oppositely
charged (or getting charged) polyelectrolytes obviously take an important and significant part in a domain of self-organizing polymer systems. Such macromolecular
co-assemblies built up from linear polyions have attracted the attention of experts in
polymer science for a long time [4–9]. Nowadays, one can confidently relate IPECs
to smart and intelligent functional complex polymers having a pronounced tendency
toward self-organization. Also of interest is the response of IPECs to minor variations
in their environment (particularly to changes in pH, ionic strength, temperature, etc.)
via considerable conformational changes and the whole spectrum of their physicochemical and mechanical characteristics. The unique simplicity of preparation of
IPECs, together with an availability of linear polyelectrolytes, make such macromolecular co-assemblies and IPEC-based materials very promising for numerous
applications.
IPECs have been demonstrated to act as effective flocculants and surface
modifiers [10–13]. One can emphasize the successful application of IPECs as effective and available binders for soils and grounds in the aftermath of the accident in
the Chernobyl atomic power station (Ukraine).These macromolecular co-assemblies
were used to suppress erosion of soils and grounds and thus to prevent radionuclide
contamination caused by spreading of radioactive particles [10, 14]. Twenty-five
years later, IPECs have again attracted attention because of similar problems arising
from the accident in the Fukushima Daiichi atomic power station (Japan) [15, 16].
Another attractive application of IPECs is for medical purposes in the design of
pharmaceuticals for targeted drug delivery followed by controlled release, e.g., for a
nonviral gene delivery into cells [17, 18].
Nowadays, we clearly see that the domain of interpolyelectrolyte interactions
and IPECs is rapidly developing, involving relatively new areas of science and
opening new possibilities for application of these macromolecular co-assemblies.
With IPECs as templates, novel organic–inorganic complex systems and hybrid
nanocomposites based on these are successfully being developed. During the last
few years, studies on IPECs have been considerably extended as polyelectrolytes
with new (nonlinear) topologies have become available. This becomes possible due
Advanced Functional Structures Based on Interpolyelectrolyte Complexes
175