Radiation-induced synthesis of hydrophobic cryogels with rapid and high absorption of organic solvents and oils

Abstract

Herein, for the first time, macro-porous hydrophobic cryogels of poly( iso- decyl acrylate- co -ethylene glycol dimethacrylate) P(IDA- co -EGDMA) have been successfully fabricated through γ -ray radiation-induced cryo-polymerization. This synthesis route is highly advantageous over the reported redox and UV-radiation routes for the synthesis of hydrophobic cryogels considering the high energy and the penetrating depth of γ -ray, which favours the fabrication of larger cryogels within shorter duration. The effects of radiation time, dose rate, amount of cross-linker, solvent type and solvent amount on the cryo-polymerization were studied in detail, which were based on the measurements of gel fraction and contact angle as well as the characterizations of Fourier transform infrared spectroscopy, thermal gravimetric analysis and scanning electron microscopic examination. The fabricated macro-porous cryogels were used as a sorbent for different organic solvents and oils. Using benzene as a common organic solvent, the absorption equilibrium was reached within only 60 s and the absorption capacity varied in the range of 16–20 g/g depending on the cryogel morphology and crosslinking density. As for the halogenated solvents, P(IDA- co -EGDMA) cryogels absorbed 25–29 g/g of chlorobenzene, bromobenzene, iodobenzene and tetrachloromethane. Those cryogels withstood high temperature (150 °C) deprived of any alteration in absorption capability and pore morphology. The cryogels reusability was also confirmed with keeping absorption capacity and cryogel mass up to 10 cycles. Rapid synthesis of macroporous cryogels with rapid and good absorption for organic solvents have been attained through γ -ray radiation-induced cryo-polymerization. • Hydrophobic cryogels were obtained through γ -ray radiation. • Cryogel morphology was modulated with cryo-polymerization parameters. • Cryogels exhibited rapid and high absorption capacity. • Cryogels were recyclable, reusable and stable.