Preparation of ionic-bonded superabsorbent polymers and their surface-crosslinking with silicate materials

Abstract

The purpose of this study is to improve the low absorbency under load, the permeability, and absorption rate of a superabsorbent polymer (SAP)-based on itaconic acid by introducing a polycationic salt into the core-SAP to form ionic bonds as well as by adding modified silica or hollow glass microsphere to the surface-crosslinked SAP. The core-SAP was synthesized by aqueous polymerization using itaconic acid, vinyl sulfonic acid, and tetra (ethylene glycol) diacrylate. The absorbency under loading of the core-SAP was improved using aluminum sulfate and zirconium sulfate as polycationic salts. We performed FT-IR analysis to characterize the structure of core-SAPs. The presence of polycation salts in the core SAP was confirmed through XPS analysis. Modified silica and hollow glass microsphere were added during the surface crosslinking process to improve the absorption properties and the permeability of SAP. The surface-crosslinked core-SAP with the modified silica showed increased permeability. The surface-crosslinked SAP containing hollow glass microsphere of 1 wt% showed the highest absorbency under load and permeability. In addition, the surface-crosslinked SAP with glass sphere increased the absorption rate. The surface structure of the surface-crosslinked SAP with modified silica or hollow glass microsphere was observed by SEM analysis.