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reaction solution contained hydroxyethyl cellulose, Acre-Lamido, MBAA,
potassium persulfate and glutaraldehyde, a result of both mesh formed of cross-
linked PAA occurs crosslinking hydroxyethyl cellulose with glutaraldehyde. The
resulting hydrogel had the ability to shrink at higher temperatures.
More extensive information on the hydrophilic IPN, which combine ionic
and non-ionic polymers. Apply different combinations of nets nonionic polymers
such as PVA [38-40] PEO [41,42], the IPA of polymers [43,44], and
vinylpyrrolidone (VP) [45, 46] with ionic polymers, both anionic and cationic
nature . The main practical problems to be solved in the synthesis of IPN, about
the same as that already discussed when considering the composite materials of
another type, namely, search management capabilities and mechanical properties
of the hydrogel sensitive to various influences. The combination of nonionic and
ionic polymers in the composite material allows to obtain hydrogels, and having
thermal sensitivity and sensitivity to pH and ionic strength of the medium [43,
44]. Known hydrogels are sensitive to the electric field [39].
A characteristic feature of ion-ionic hydrogels is the high value of the
elastic modulus of the material at low and at high pH [42]. In acidic
environments IPN hydrogel based on crosslinked polyacrylic acid polymer and a
nonionic polymer (PEO) collapse of - the weak ionization of the carboxyl
groups. Under these conditions, the hydrogel acquires increased rigidity due to
partial dehydration and formation of a large amount of intermolecular hydrogen
bonds. Conversely, increasing pH (above rKaPAK-4.7) strengthens the hydrogel
swelling ionic component that causes stretching mesh nonionic polymer are
insensitive to pH changes, and as a result, the occurrence of internal stresses in
the material of stiffening composite hydrogel. The possibility of realizing these
effects are largely dependent on the crosslinking density of PEO. Properties of
hydrogel related to the amount of physical entanglements between
macromolecules and vary very widely, a water content of 58 to 90 wt.
%
Modulus - from 1 to 19 MPa. These properties allow us to consider a composite
hydrogel as a promising material to replace natural tissue (cartilage, the cornea
of the eye), are subjected to considerable mechanical stress.
The presence of two modes swelling hydrogel composite, in which
functions are performed by ionic polymers of acrylic acid or MAA, opens up
new possibilities for creating means, controlled delivery of drugs [38, 41]. Ionic
hydrogels based on these acids are often tested at two pH values (1 and 27. 4),
corresponding to the state of the environment in the stomach and intestines of
humans. When used as a carrier for drugs is usually observed the following
picture. In the acidic environment of the hydrogel due to the collapse occurs
"explosion-like" release of the drug and also fast process stops before full release
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