Swelling behavior of anionic acrylamide-based hydrogels in aqueous salt solutions: Comparison of experiment with theory

Abstract

A series of hydrogels were prepared from acrylamide and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) monomers with 0 -80 mol % AMPS and using N,NЈ-methylenebis(acrylamide) as the crosslinker. The swelling capacities of hydrogels were measured in water and in aqueous NaCl solutions. The volume swelling ratio q v of hydrogels in water increases sharply when the mole fraction f c of AMPS increases from 0 to 0.06. At higher values of f c from 0.06 up to 0.18, no change in the swelling capacities of hydrogels was observed; in this range of f c , q v becomes nearly constant at 750. However, as f c further increases, q v starts to increase again monotonically over the entire range of f c . At a fixed value of f c , the swelling ratio of hydrogels decreases with increasing salt concentration in the external solution. The results of the swelling measurements in aqueous salt solutions were compared with the predictions of the Flory-Rehner theory of swelling equilibrium. It was shown that the theory correctly predicts the swelling behavior of hydrogels up to 80 mol % charge densities. The method of estimation of the network parameters was found to be unimportant in the prediction of the experimental swelling data. The network parameters used in the simulation only correct the deficiency of the swelling theory.

Preparation and physical properties of hyaluronic acid‐based cryogels

“…A lesser degree of swelling in salt solutions as compared with water is a typical behavior of polyelectrolyte gels owing to a decrease in the concentration difference of counterions inside and outside the hydrogel. 40 In the present case, the swelling pressure due to the counterions of the carboxyl groups of HA is reduced in PBS, leading to a 40 to 60% reduction in the gel volume. Furthermore, it was noticed that EGDE concentration used in the gel preparation, i.e., the crosslinker ratio X, has an impact on the equilibrium swelling degree of cryogels in PBS solution.…”

Removal of methylene blue from aqueous solutions by poly(2-acrylamido-2-methylpropane sulfonic acid-co-itaconic acid) hydrogels

“…According to this figure, increasing the AMPS concentration at monomer feed composition, increased the adsorption capacity, due to its strongly ionizable sulfonate group [12][13][14][15]. The surface morphology of various ratios of poly(AMPS/IA) hydrogels was detected by SEM and shown in Fig.…”

Multiphysics modeling of responsive characteristics of ionic-strength-sensitive hydrogel

“…In this section, the present MECis is validated by comparing the simulation results with the experimental data published by Dhara et al (Dhara et al 1999), Caykara et al (Caykara and Dogmus 2005), Okay et al (Okay et al 1998) and Hooper et al (Hooper et al 1990), respectively.…”

“…A series of poly(AAm-co-AMPS) (PAAS) hydrogels were prepared by acrylamide (AAm) and 2-acrylamideo-2-methylpropanesulfonic acide (AMPS) monomers, and N, N′-methylenebis(acrylamide) as the crosslinker (Okay et al 1998). As AMPS is a strongly dissociating electrolyte, the amount of AMPS may be considered to be equal to the fixed charge density of the hydrogels.…”

“…Probably, Flory may be the first who introduced the contribution of ionic concentration of the surrounding solution into the swelling of hydrogel (Flory 1953;Flory and Rehner 1943a, b). Based on Flory's model, several research groups presented different models for prediction of ionic concentration and the swelling of the smart hydrogel (Baker et al 1994(Baker et al , 1995English et al 1996;Okay et al 1998). Instead of using ionic concentration in the Flory type models, Brannon-Peppas and Peppas proposed a model incorporating the ionic strength I for the ionic contribution to the chemical potential which is one main driving source to expand the hydrogel (Brannon- Peppas and Peppas 1991).…”