Autori: Artur J.M. Valente,a,* Abílio J.F.N. Sobral,a Alfonso Jiménez,b Sílvia Patachia,c Ana R.C.B. Oliveira,a Victor M.M. Loboa

Editorial: Elsevier, European Polymer Journal, 42(9), p.2059-2068, 2006.

Rezumat:

The calix[4]pyrrole (1) was synthesized and characterized. The incorporation of this macrocycle in polyacrylamide gels was carried out. The presence of meso-octamethyl-porphyrinogen inside of gel was checked by using infrared spectroscopy, differential scanning calorimetry and swelling studies. The swelling degree of these hydrogels in equilibrium with different non-associated electrolytes (NaCl, LiCl, KCl, CaCl2 and AlCl3) was measured in a concentration range 0.1 mol dm-3 to 0.5 mol dm-3. Although no significant alterations in the swelling degree can be found to the different 1:1 electrolytes, when the cation charge of unsymmetrical electrolytes increases the gel swells in a significant way. This swelling process is enhanced by the presence of calyx[4]pyrrole. The effect of alkaline hydrolysis of polaycrylamide-based hydrogels was also analyzed. The hydrolyzed hydrogels collapse in the presence of the electrolytes; such behaviour is dependent on the hydrolysis degree, electrolyte charge and calyx[4]pyrrole.

Cuvinte cheie: hydrogels, polyacrylamide, calyx[4]pyrrole, swelling degree, hydrolysis