Cross-linked hydrophilic gels from ABA block copolymeric surfactants

Gelation of aqueous solutions of poly(oxyethylene)-poly(oxypropylene)-poly(oxyethylene) block co-polymeric non-ionic surfactants (Pluronics or poloxamers) by the action of γ-rays is reported. Poloxamers with ethylene oxide content below 70% do not gel under the conditions studied, but appear to undergo chain scission, as there is a decrease in cloud point and an increase in hydrodynamic radius which is most likely to be due to decreased association of the more hydrophobic polymer. The gels obtained from poloxamers with ethylene oxide content over 70% have a high water uptake capacity. The possibility of using these gels as sustained release drug delivery systems is discussed. (Auth.)