Abstract:
The possibility of controlling the properties of network copolymers of polyethylene glycol maleate by changing
external factors (pH of medium, temperature, the presence of organic solvents and low molecular weight
inorganic salts) has been studied. Swelling capacity of the copolymers investigated was studied using gravimetric
method. It has been established that the hydrogels are sensitive to the change of pH of medium and the
copolymers’ samples undergo reversible swelling-collapse-swelling transfer. Basic factors which determine
the swelling of the gels studied are electrostatic repulsion of similarly charged carboxylic groups and appearance
of opposite charges on macrochains as a result of the hydrolysis of acrylamide segments. It has been
shown that the hydrogels of polyethylene glycol maleate with acrylamide are sensitive to the influence of
temperature and the dependence of the swelling degree has extreme character. The sensitivity of the copolymers
to the presence of low molecular salts has been established. Combined regimen of their behavior in the
presence of salts is due to the hydrolysis of amide bond in the segments of the copolymer of polyethylene
glycol maleate. When adding organic solvent to the medium which is the polymer swollen in water continuous
contraction of the samples studied is observed and it leads to the shrinkage of the hydrogels’ size. Suppressive
action of organic solvents on swelling of the copolymers of polyethylene glycol maleate with
acrylamide is explained by the polarity of the solvents.
