Water Interactions in Hybrid Polyacrylate-Silicate Hydrogel Systems

Abstract

Hybrid polyacrylate-silicate hydrogels were obtained in the presence of N,N′-methylenebisacrylamide (NNMBA) as the cross-linking monomer and sodium thiosulphate/potassium persulphate (NTS/KPS) as the redox initiators. The results of the tests allowed us to conclude that a hybrid structure with a polyacrylate scaffolding and a silicate matrix had been obtained. The results of the rheological analysis revealed that the hydrogel sample with a 1:7 mass ratio of sodium water glass to the sodium polyacrylate is characterized by the highest complex viscosity. Thermal analysis (Thermogravimetry/Differential Scanning Calorimetry (TG/DSC)) showed that water begins to evaporate at higher temperatures, from 120 °C to even 180 °C. These results were confirmed by mid-infrared spectroscopy (MIR) and nuclear magnetic resonance spectroscopy (NMR) analysis. Differences in the intensity of the peaks derived from water in the MIR spectra indicate that most of the water is bounded. In turn, NMR results showed that the mobility of water molecules decreases as the amount of sodium water glass in the mixture increases.

Effect of Composition on the Physicochemical Properties of Cross-Linked Poly(sodium acrylate)/Sodium Silicate Hydrogels

“…Based on our previous works [23][24][25], silicate-polymer hydrogels, where the silicate part was sodium water glass and the polymer part was sodium polyacrylate, were used as the research material. As a polymer component, from among the available vinyl monomers such as acrylic monomers, methacrylates, vinyl acetates and vinyl alcohol, we chose sodium acrylate due to the fact that its polymer can bind significant amounts of water and polymerize in the presence of other chemical substances, and the polymerization process itself is not complicated.…”

The Effect of Humidity on the Atomization Process and Structure of Nanopowder Designed for Extinguishment

“…This implies that the chains and/or rings formed by various forms of donorization are the most likely structures in the liquid water at temperatures between 7 °C and 100 °C, and that the basic “unit” is the hydronium ion H 3 O + (oxonium), which at higher temperatures >100 °C “breaks down” relatively easily into H 2 O and H*. There is a lack of detailed data on the mechanism of this decay, although various suggestions can be found about the leading role of the 1b1’ orbital in electron supply at temperatures above 100 °C [ 3 , 18 ]. Thus, the total Equation (2) in the nitrogen environment is: C + H 3 O* + OH* + 2NO* = CO 2 + 2H 2 O + N 2 …”