Thermo-switchable charge transport and electrocatalysis using metal-ion-modified pNIPAM-functionalized electrodes

Metal ions (Ag⁺, Cu²⁺, Hg²⁺) are incorporated into an electropolymerized, poly(N-isopropyl acrylamide), pNIPAM, thermosensitive polymer associated with an electrode using the "breathing-in" method. The ion-functionalized pNIPAM matrices reveal ion-dependent gel-to-solid phase-transition temperatures (28 ± 1 °C, 25 ± 1 °C, 40 ± 1 °C for the Ag⁺, Cu2+, and Hg²⁺modified pNIPAM, respectively). Furthermore, the ion-functionalized polymers exhibit quasi-reversible redox properties, and the ions are reduced to the respective Ag°, Cu°, and Hg° nanocluster-modified polymers. The metal-nanoeluster-functionalized pNIPAM matrices enhance the electron transfer (they exhibit lower electron-transfer resistances) in the compacted states. The electron-transfer resistances of the metal-nanocluster-modified pNIPAM can be cycled between low and high values by temperature-induced switching of the polymer between its contracted solid and expanded gel states, respectively. The enhanced electron-transfer properties of the metal nanocluster-functional ized polymer are attributed to the contacting of the metal nanoclusters in the contracted state of the polymers. This temperatureswitchable electron transfer across a Ag°-modified pNIPAM was implemented to design a thermo-switchable electrocatalytic process (the temperature-switchable electrocatalyzed reduction Of H₂O₂ by Ag°-pNIPAM).