Novel thermo-sensitive linear and crosslinked copolymers of vinyl ether of ethylene-glycol and vinyl butyl ether have been synthesized by gamma-irradiation copolymerization. The effect of comonomer hydrophobicity, neutral salts addition and nature of cations and anions on the position of lower critical soluble temperature of water-soluble copolymers and swelling-deswelling behavior of networks is demonstrated. The combination of thermosensitivity and pH sensitivity of hydrogels are realized in the case of crosslinked terpolymers. Copyright

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Novel thermo‐sensitive linear and crosslinked copolymers of vinyl ether of ethylene‐glycol and vinyl butyl ether have been synthesized by gamma‐irradiation copolymerization. The effect of comonomer hydrophobicity, neutral salts addition and nature of cations and anions on the position of lower critical soluble temperature of water‐soluble copolymers and swelling‐deswelling behavior of networks is demonstrated. The combination of thermosensitivity and pH sensitivity of hydrogels are realized in the case of crosslinked terpolymers. Copyright © 1999 John Wiley & Sons, Ltd.

The complexation of linear chitosan with hydrogel of poly(acrylic acid) was studied in acetic acid solutions. It was found that the complexation is accompanied by contraction of hydrogel samples with formation of turbid layer on their surface. The dynamic changes of swelling ratio of poly(acrylic acid) hydrogel in course of the interaction with chitosan are interpreted from the diffusion theory point of view considering the properties of double electric layer on hydrogel-solution boundary. The FTIR spectroscopy method revealed the electrostatic mechanism of interaction between poly(acrylic acid) hydrogel and chitosan. The spectrum of polycomplex shows the bands, which are characteristic for both poly(acrylic acid) (1725, 1450, 1249 cm -1 ) and chitosan (1648, 1536, 1165, 1091, 1023 cm -1 ) confirming the sorption of the later polymer by hydrogel of poly(acrylic acid). The possibility of encapsulation of antibiotic levomycetin into polycomplex hydrogels as well as its release from the capsules has been studied. It was found that the maximal value of the drug released from the polycomplex capsule is achieved after the longer period in comparison with control experiment with its release from pure PAA hydrogel. It was shown that the interpolymer interactions between oppositely charged linear polymers and hydrogels could be successfully used for preparation of encapsulated forms of various physiologically active substances.

<p>The formation of H-bonded interpolymer complexes between linear and cross-linked poly(acrylic acid) and poly(vinyl ether of ethyleneglycol) is considered. The effects of pH and concentrations of polymers solution as well as the nature of the solvent on the complexation processes are discussed. It was found that the complexes are formed in aqueous solutions only below some critical pH value, which depends on the concentration of polymers and ionic strength of the solution. The interaction between gel of poly(acrylic acid) swollen in alcohol with solution of linear poly(vinyl ether of ethyleneglycol) is accompanied by formation of turbid layer of polycomplex and contraction of gel.</p>