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Macro-porous poly(lauryl acrylate) cryogel sheets as oil-sorbents were prepared through UV-radiation cryo-polymerizations in 1, 4-dioxane at low temperatures (−5, −2 and 0 °C) within 30 min. The influences of total monomer concentration, crosslinking monomer amount and polymerization temperature on the formation of cryogels were studied. The chemical structure and porous morphology were characterized through the techniques of Fourier transform infrared spectroscopy, thermal gravimetric analysis, contact angle measurement and scanning electron microscopy, confirming the features of high hydrophobicity, macro-porosity and good thermal stability. As well, the comparison between conventional gels prepared at room temperature and cryogels at lower temperatures was made, showing the higher rate of cryo-polymerization than conventional polymerization under the same UV-radiation condition. The swelling investigation was carried out with several organic solvents and oils. Enhanced performance of oil absorption was observed for those cryogels considering the absorption capacity and absorption rate. Variation of initiator amount and acrylate monomers could also modulate the absorption capacity. Those cryogel oil-sorbents exhibited wide adaptability, good reusability and high-temperature tolerance. Thus, this rapid and low-cost fabrication opens out a novel pathway to prepare efficient oil-sorbents used in waste water treatment. • Polyacrylate cryogels were prepared under UV-radiation within 30 min. • Cryogel morphology were modulated with various parameters, principally temperature. • Macro-porosity and pore-wall feature are extremely important to oil-sorbent capacity. • Oil-sorbents have wide adaptability, good reusability and high-temperature tolerance. [ABSTRACT FROM AUTHOR]

Temperature-responsive macro-porous cryogels of poly(N -iospropylacryamide- co -acrylamido-2-methylpropane sulfonic acid) [P(NIPAM- co -AMPS)] were prepared through redox-initiated cryo-polymerization at −12, −18 and −24 °C. Silver or gold nanoparticles (AgNPs or AuNPs) were formed inside P(NIPAM- co -AMPS) cryogels through the thermal reduction of absorbed AgNO 3 or HAuCl 4 , resulting in hybrid cryogels immobilized with AgNPs or AuNPs. Fourier transform infrared spectroscopy, thermal gravimetric analysis and X-ray diffraction confirmed the chemical composition. Cryogel morphology and nanoparticle distribution were investigated through scanning and transmission electron microscopies. By checking swelling ratio in neutral water, the temperature response of cryogels was identified. The hybrid cryogels were used as the catalysts to reduce p -nitrophenol with NaBH 4 at different temperatures and pHs. The hybrid cryogel with AuNPs had the higher catalytic activity than the counterpart hybrid cryogel with AgNPs. The catalytic activity of hybrid cryogels increased with temperature and pH. The temperature response of cryogels facilitated their isolation from the reaction mixture. Since AuNPs were fixed tightly onto the cryogel pore-wall and hardly lost, hybrid cryogels with AuNPs demonstrated no decrease in catalytic activity for 5 cycles of p -nitrophenol reduction. P(NIPAM- co -AMPS) hybrid cryogels with gold or/and silver nanoparticle was used to catalyze the reduction of p -nitrophenol with the performances of high rate and reusability. Image 1 • Thermo-responsive and macro-porous cryogels of P(NIPAM- co -AMPS) were prepared. • AgNPs or AuNPs were incorporated through in-situ thermal reduction inside the cryogels. • Hybrid cryogels exhibited the high catalytic activity for p -nitrophenol conversion. • Cryogel morphology and metal nanoparticle affected greatly the catalytic activity. [ABSTRACT FROM AUTHOR]