Mechanical milling of thermoresponsive poly(N-isopropylacrylamide) hydrogel for particle-oriented oil-water separation

The separation of oil and water is widely studied because of the promise of cleaning up oil spills. One pathway is with thermosensitive polymer-based hydrogels. As hydrogels are raised to the lower critical solution temperature (LCST), they undergo a change of state, from hydrophilic to hydrophobic. Oil-water separation using hydrogels in particle form that are responsive to external stimuli (e.g., magnetic field and temperature) are of great interest. This work uses a novel approach of ball milling dry hydrogel into different sizes and testing oil-water separation efficacy. This study investigated the potential for ball milling P(NIPAAm) bulk hydrogel into small particles size ranges (0-45, 45-90, 90-106, 106-150, and 150+ mu m) and the resulting impact on oil-water separation. It was observed that the LCST for the p(NIPAAm) in gel form was 32 degrees C while increasing to similar to 40 degrees C for the powdered form. It was found that the hydrogel particles of different size ranges managed to capture 196, 207, 208, 162, and 124% of its weight in oil, respectively. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48771.