The evaluation of temperature and pH influences on equilibrium swelling of poly(n-isopropylacrylamide-co-acrylic acid) hydrogels

Autor: Zdravković Aleksandar S., Nikolić Ljubiša B., Ilić-Stojanović Snežana S., Nikolić Vesna D., Savić Saša R., Kapor Agneš J.
Jazyk: English<br />Serbian
Rok vydání: 2017
Předmět:
Zdroj: Hemijska Industrija, Vol 71, Iss 5, Pp 395-405 (2017)
Druh dokumentu: article
ISSN: 0367-598X
2217-7426
DOI: 10.2298/HEMIND161018001Z
Popis: Hydrogels are synthesized by the method of radical polymerization of monomers: N-isopropylacrylamide (NIPAM) and acrylic acid (AA). Characterization of poly(N-isopropylacrylamide- co-acrylic acid) hydrogels, p(NIPAM/AA), has been performed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and by determination of the swelling behaviour in aqueous solutions at different temperatures (25, 31 and 37°C) and pH values (2.2, 4.5, 6 and 6.8). After lyophilisation in the solution at pH 6 and temperature of 25°C, p(NIPAM/AA) hydrogels have rapidly reached equilibrium degree of swelling, αe, in comparison to non-lyophilized samples. The mechanism of solvent transport within matrix in lyophilized samples corresponds to less Fickian diffusion, whereas Super case II diffusion is characteristic for non-lyophilized samples. p(NIPAM/AA) hydrogel with 1.5 mol% of ethylene glycol dimethacrylate (EGDM) at the temperature of 25°C and pH 6.8, has reached the highest swelling equilibrium degree, αe = 259.8. The results of swelling studies have shown that p(NIPAM/AA) hydrogels can be classified as superabsorbent polymers (SAPs). For the evaluation of pH and temperature influences on synthesized hydrogels swelling, a full three-level experimental design has been used. Two-factor interaction model (2FI) is the most optimal model of a full three-level experimental design for representing the swelling equilibrium degree of p(NIPAM/AA) hydrogels as a function of investigated parameters, i.e., temperature and pH. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR-34012]
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