Poly(Acrylic Acid)-Sodium Alginate Superabsorbent Hydrogels Synthesized by Electron Beam Irradiation Part I: Impact of Initiator Concentration and Irradiation Dose on Structure, Network Parameters and Swelling Properties

Gabriela Craciun; Ion Cosmin Calina; Maria Demeter; Anca Scarisoreanu; Marius Dumitru; Elena Manaila

doi:10.3390/ma16134552

Poly(Acrylic Acid)-Sodium Alginate Superabsorbent Hydrogels Synthesized by Electron Beam Irradiation Part I: Impact of Initiator Concentration and Irradiation Dose on Structure, Network Parameters and Swelling Properties

Materials (Basel). 2023 Jun 23;16(13):4552. doi: 10.3390/ma16134552.

Authors

Gabriela Craciun¹, Ion Cosmin Calina¹, Maria Demeter¹, Anca Scarisoreanu¹, Marius Dumitru¹, Elena Manaila¹

Affiliation

¹ Electron Accelerators Laboratory, National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor St., 077125 Magurele, Romania.

Abstract

In the present paper, hydrogels based on acrylic acid (20%), sodium alginate (0.5%) and poly(ethylene oxide) (0.1%) were obtained by electron beam irradiation at room temperature with doses between 5 and 20 kGy, using potassium persulfate in concentrations up to 0.3% as a reaction initiator. The influence of initiator concentration and irradiation dose on hydrogel network parameters, swelling and deswelling behavior, gelation and degradation points, structure and morphology were investigated. Cross-link density increased with the irradiation dose and initiator addition, except at 20 kGy. The gel fraction was over 87.0% in all cases. Swelling experiments in distilled water showed swelling degrees of 40,000% at an irradiation dose of 5 kGy when a concentration of 0.1% initiator was added. A relationship between the swelling degree and irradiation dose, cross-linking degree (that increases from 0.044 × 10² to 0.995 × 10² mol/cm³) and mesh size (that decreases from about 220 nm to 26 nm) was observed. The addition of only 0.1% of PP led to the obtaining of hydrogels with a swelling degree of 42,954% (about 430 g/g) at an irradiation dose of 5 kGy and of 7206% (about 62 g/g) at 20 kGy, which are higher percentages than those obtained in the same irradiation conditions but without PP.

Keywords: acrylic acid; electron beam irradiation; hydrogels; poly(ethylene oxide); potassium persulphate; sodium alginate.

Grants and funding

This work was supported by a grant of the Ministry of Research, Innovation and Digitization, CNCS–UEFISCDI, project number PN-III-P2-2.1-PED-2021-2151, within PNCDI III and by the Romanian Ministry of Research, Innovation and Digitalization under Romanian National Core Program LAPLAS VII—contract no. 30N/2023.