Comparison of Structural, Water‐Retaining and Sorption Properties of Acrylamide‐Based Hydrogels Cross‐Linked by Physical and Chemical Methods

Abstract

Two series of hydrogels based on acrylamide and its copolymers with acrylonitrile and acrylic acid were synthesized by two cross‐linking methods – chemical (using N,N′‐methylene bis‐acrylamide) and physical (using montmorillonite (MMT)) ones. The structure of the gels was characterized by Fourier Transform Infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The swelling and sorption properties were analyzed as a function of both the monomer composition and the cross‐linking method. The shift of the band corresponding to Si−O (995–1030 cm−1) confirmed the formation of intercalation structures for MMT‐cross‐linked gels. Moreover, physically cross‐linked gels demonstrated a non‐monotonic dependence of the swelling degree on the MMT concentration, and acrylamide‐acrylic acid copolymer MMT‐cross‐linked gels showed pH sensitivity and the highest swelling degree of 150 g/g. The highest sorption capacity towards cadmium(II) ions was demonstrated by acrylamide‐acrylic acid copolymer gels, both covalently cross‐linked (30 mg/g) and MMT‐cross‐linked (8.9 mg/g).

An Overview of Polymeric Hydrogel Applications for Sustainable Agriculture

“…Consequently, the toxicity level is reduced. Polymers can be cross-linked by altering external factors like pH and temperature, as well as using physical agents, such as nanoparticles that act as anchoring points for the polymers through physical interactions, including hydrogen bonding and Van der Waals interactions [12,65,66]. However, this method results in hydrogels with limited mechanical resistance because of their weak connections [12,65].…”