pH-responsive sodium alginate-based superporous hydrogel generated by an anionic surfactant micelle templating.

A novel sodium alginate-based superporous hydrogel (SPH) was prepared by the grafting copolymerization and micelle templating formed by the self-assembled anionic surfactant sodium n-dodecyl sulfonate (SDS). Fourier transform infrared (FTIR) spectra demonstrated that SDS was removed from the final hydrogel network. The formation mechanism of NaAlg-based SPH was proposed. Effect of SDS concentration on the morphologies and pore structure of the hydrogel was evaluated by Scanning Electron Microscopy (SEM), and the SDS-1.92 mM sample displays homogeneous and well-defined pores, which contribute to improve swelling ratio and swelling rate. The time-dependent swelling behaviors of the SDS-1.92 mM samples in various salt and pH solutions were investigated. The swelling in multivalent salt (Ca(2+), Al(3+))/pH 2 solutions displayed a well-known "overshooting effect", whereas, its swelling kinetics in Na(+)/pH 3-12 solutions followed Schott's pseudo second-order swelling kinetics model.