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and ion-di-dipole interactions between macromolecules. The possibility of
occurrence of interpolymer complexes in such systems is determined not only by
the presence in the structure of macromolecules of appropriate functional groups
and molecular characteristics of polymers that provide complementarity
macromolecules. Laws of formation of interpolymer complexes are discussed in
detail in reviews and monographs [1-5]. Therefore, we focus on the provisions
that define the possibility of the formation of interpolymer complexes in the
form of composite hydrogel and intentionally did not use the term "biphasic
hydrogel" as a fact of phase separation in such systems is not always proven. But
we can assume that at the micro- or nanoscale phase separation in some cases
should occur. This is explained by the fact that complementarity is not always
observed throughout the macromolecules with various types of polymers
irregularities. Interpolymer complex - a sequence of alternating hydrophobic
regions are relatively complementary and non-complementary fragments of
hydrophilic macromolecules.
From the nature of hydrophilic polymers resulting composite hydrogel
complex is water-soluble complex and the complex released from the solution as
a separate phase. Examples of such systems are hydrogels based on methacrylic
acid (PMAA) and PEO [6-11], produced by the emergence of the hydrogen
bonds between the carboxyl groups and oxygen polyester chains. In [9] it noted
that it is advisable to obtain a hydrogel composition with the content in a mixture
of 5-10
%
PEO. At higher concentrations, along with PEO hydrogel complex
contains free polyester molecule. Another example of hydrogen bonding - is the
formation of the composite hydrogel PVA-carboxyl containing polysaccharide
(xanthan) [12]. It is known as interpolymer complexes of polyacrylic acid (PAA)
and PAA, PIP, PVP, PVA [13]. Stronger interpolymer complexes are formed
through ionic bonding [1-5, 14], synthetic and natural polymers that can
participate in a complexation. Especially strong polyelectrolyte complexes occur
between strong polyacids and poliosnovaniyami [15]. An example of such
complexes - reaction products of sodium polystyrene sulfonate and polyvinyl
benzyltri methylammonium chloride [16]. The driving force behind the
formation of such complexes - increase in entropy of the system due to the
release of low-molecular counter-immobilized to the complex formation in an
electric field polyion and cooperative nature of their interaction determines the
strength of the complexes. Known polyelectrolyte complexes with oppositely
charged polyions produced with the assistance of the natural polymer - xanthan
and chitosan [14], poly-L-lysine, and a copolymer of acrylamide and IPA [17].
The sensitivity of many hydrogels based on interpolymer complexes to
various external influences (changes in temperature, pH, ionic strength of the
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