Physical and chemical characterisation of acrylamide-based hydrogels, Aam, Aam/NaCMC and Aam/NaCMC/MgO

Abstract

To find out the best structure of acrylamide-based hydrogels, three different composites are synthesized and characterized. Polyacrylamide-based hydrogels were obtained by chemical crosslinking of MBA using acrylamide, sodium carboxymethylecellulose (NaCMC), N,N,N′,N′-tetramethylethylenediamine (TEMED) and ammonium persulfate (APS) as the initiators. The interest in MgO nanoparticles is not only due to their stability under harsh process conditions but also for human health, where they are known to be necessary minerals. It is expected that the structure of the hydrogels can be affected positively by using MgO as a nanoparticle in their composite. To control the initial burst release through modification of the structure of the matrix, the MgO nanoparticles are applied. These nanoparticles can affect the release mechanism. In the current research, FESEM, NMR, DTA/TGA and DSC are studied for the structure of polymers. In the FESEM, existing MgO inside the hydrogel system brings about a shift in the porosity of hydrogels. The 1H NMR spectrum of polymers showed characteristic proton peaks at 4.6 and 4.7, 6.1 and 6.2 ppm. An endothermic peak indicating loss of weakly bound water molecules from the hydrogel network is shown in DTA curves of hydrogels at around 80 °C. An exothermic peak at around 270 °C for Aam and Aam/NaCMC hydrogels and also a peak at 360 °C in Aam and Aam/NaCMC hydrogels and 320 °C for Aam/NaCMC/MgO is shown. The DSC profiles of the hydrogels show that water has a higher evaporation temperature in the polyacrylamide hydrogel (84 °C).The largest depression of the temperature was observed on the Aam/NaCMC/MgO hydrogel (∆T = 94 °C), which confirmed the higher hydrophilicity of Aam/NaCMC/MgO as compared to pure Aam hydrogel and Aam/NaCMC hydrogel.