Mechanical behavior of a terpolymer-based pH- and temperature-responsive hydrogel

To improve the mechanical properties of responsive polymer hydrogels, a novel polymer nanocomposite hydrogel (“polymer NC gel”) consisting of a terpolymer of acrylamide (AM), acrylic acid (AA), and 2-acrylamidomethylpropane sulfonic acid (AMPS) combined with a clay was fabricated by radical polymerization. The structural, swelling, and mechanical properties of the polymer NC gel were easily controlled by varying the initiator (ammonium persulfate) loading. The polymer NC gel presented its highest swelling capacity (395.1 g/g), tensile strength (39.7 kPa), and compressive strength (6.4 MPa) when an initiator loading of 2.0 wt% was applied. Furthermore, the effects of pH and temperature on the swelling and mechanical properties of the polymer NC gel were also investigated. The swelling and mechanical properties of the polymer NC gel were found to be strongly dependent on the pH and the temperature. These important results should facilitate further improvements in the mechanical and stimuli-responsive properties of polymer NC gels.