Synthesis and properties of hydroxyethylcellulose graft copolymers as super water-absorbents.

Abstract

Graft copolymers of hydroxyethylcellulose (HEC) and other polysaccharides (PS) [e. g., mannan, alginic acid, agar, pectin and starch] containing partially hydrolyzed polyacrylamide (P-Hyd-PAM) or poly (methyl acrylate) (P-Hyd-PMA), poly (2-dimethyl aminoethyl methacrylate) (PDM) and poly (sodium acrylate) (PAA-Na) were synthesized as super water-absorbents. The absorbency of HEC-P-Hyd-PAM was greater than that of other polysaccharides and HEC graft copolymers containing the other types of branch polymers. The HEC-P-Hyd-PAM graft copolymers absorbed deionized water and a physiological saline solution up to 1000-3000g/g and 100-300g/g of absorbent, respectively. These values were 3-5 times greater than those of commercially available super water-absorbents. The HEC and the monomers were converted to the trunk and branch polymers of the HEC graft copolymers in the yields of about 30-60% and 20-80%, respectively. With an increase in grafting, the absorbencies of water and saline solutions of HEC-P-Hyd-PAM increased and reached maxima at 150-300% grafting, while those of HEC-PDM and the compressive strength of both gels increased monotonously. The gels of HEC-P-Hyd-PAM showed a discrete volume change at certain CH3OH-H2O compositions. The absorbencies of water and saline solutions of the graft copolymers of HEC and the other polysaccharides depended on the viscosity of the trunk polymers.