Synthesis and Assessment of AMPS-Based Copolymers Prepared via Electron-Beam Irradiation for Ionic Conductive Hydrogels

In this study, ionic conductive hydrogels were prepared with 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS). Acrylic acid (AA), acrylamide (AAm), and 2-hydroxyethyl acrylate (HEA) were used as comonomers to complement the adhesion properties and ion conductivity of AMPS hydrogels. Hydrogels were prepared by irradiating a 20 kGy dose of E-beam to the aqueous monomer solution. With the E-beam irradiation, the polymer chain growth and network formation simultaneously proceeded to form a three-dimensional network. The preferred reaction was determined by the type of comonomer, and the structure of the hydrogel was changed accordingly. When AA or AAm was used as a comonomer, polymer growth and crosslinking proceeded together, so a hydrogel with increased peel strength and tensile strength could be prepared. In particular, in the case of AA, it was possible to prepare a hydrogel with improved adhesion without sacrificing ionic conductivity. When the molar ratio of AA to AMPS was 3.18, the 90° peel strength of AMPS hydrogel increased from 171 to 428 g(f)/25 mm, and ionic conductivity slightly decreased, from 0.93 to 0.84 S/m. By copolymerisation with HEA, polymer growth was preferred compared with chain crosslinking, and a hydrogel with lower peel strength, swelling ratio, and ionic conductivity than the pristine AMPS hydrogel was obtained.