Snežana Ilić-Stojanovića, Ljubiša Nikolića, Vesna Nikolića, Slobodan D. Petrovićb, Mihalo Stankovića, Slobodanka Jovanovićc

University of Niš, Faculty of Tehnology; University of Belgrade, Faculty of Tehnology and Metalurgy; Ekonomic Institute

Patent RS 53 220 B

Hydrogels are materials designed for use in human medicine. They have application in the control of drug release rate, by limiting the degradation and toxicity. A typical representative of the temperature-sensitive polymer is poly(N-isopropylacrylamide), p(NIPAM), which contains hydrophilic and hydrophobic groups. The lower critical solution temperature, LCST, at which p(NIPAM) passes through the phase transition is 32°C. P(NIPAM) hydrogel swells at temperatures below the LCST and exhibits a hydrophilic nature, because the hydrogen interactions of the polymer chains with the molecules of water are dominant. Above LCST, hydrogen bonds with water molecules break up, hydrophobicity p(NIPAM) leads to contraction, which is causing swelling degree decrease. The presence of new bands (which are not found in FTIR spectra of monomers and crosslinker) and formed hydrogen bonds, indicating the successful hydrogels copolymerization. SEM analysis indicates that the hydrogels are crystalline and macroporous (pore size of 0.1- 1 μm). The content of residual monomers is within acceptable limits for pharmaceutical use and shows that conversion of the reactants is almost complete.

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