In this paper, the super-absorbent,

In this paper, the super-absorbent, self-crosslinking sodium polyacrylate was synthesizedby means of reversed-phase suspension polymerization under gamma-ray irradiation andthe water-absorbing mechanism of the self-crosslinking hydrogel was revealed. Somephysical parameters of such a network were estimated and investigated. The stablesuspension polymerization of sodium acrylate was carried out in the presence of asurfactant complex consisting of anionic surfactant dodecylbenzen sulfonic sodium (DSS)and nonionic surfactant Span60 or Span20 with a certain ratio. The dual-electronic structureresulted from such a surfactant complex makes the dispersed monomer solution droplets astable suspension in organic solvent. The water-sorbability was related to the radiationconditions such as dose, dose rate, and degree of monomer neutralization. Only under highdose and dose rate, some initiated branch side species on the main macromolecular chaincan couple each other and cause a self-crosslinking network which may contain a lot ofwater. The gel dose was about 1.57 kGy (radiation dose unit), and G(X), or G valueexpressed as crosslinking probability at certain energy of 100 ev, was calculated and foundto be 2.46 (1/100 ev). The water-sorbing procedure includes three stages, e.g., sorption onthe pore surface, ionization of the fixed charges in the network, and swelling equilibrium.The crosslink chain length in the self-crosslinked sodium polycrylate network, expressed asMc, can be calculated and related to gel dose.