Thermoresponsive surface functionalization of FeRh alloy through PNIPAM grafting

The smart thermoresponsive composite of PNIPAM/FeRh by chemical grafting of PNIPAM polymer on substrate of FeRh alloy were fabricated and studied. The characteristic peaks at 1690 (C=O), 2480–3000 (CH), and 3280 (N–H) observed on IR-FTIR spectra of PNIPAM/FeRh corresponded to the functional groups of PNIPAM and confirmed grafting of the polymer on the surface of FeRh substrate. The measurements of wetting demonstrated the changes of contact wetting angle from 69.3±1.5° at 27 °C to 76.9±1.2° at 40 °C attributed with transformation of PNIPAM polymer from the hydrated to the dehydrated state due phase transition with lower critical temperature at ~32 °C. The changes in surface topography of PNIPAM polymer in results of phase transition with lower critical solution temperature in PNIPAM were observed using atomic force microscopy measurements in temperature range 30–50 °C in heating and cooling.