Thermally responsive reduced graphene oxide with electroactive functionality for controllable electroanalysis

Abstract

A thermally responsive hybrid poly(NIPAm-b-BVIm[FcCOO])-rGO composed of block co-polymer poly(NIPAm-b-BVImBr), reduced graphene oxide (rGO) and electroactive anions was designed and synthesized to achieve electroactive functionality. It is the polymeric ionic liquids (PILs) segment in the block co-polymer that integrated the three different components into a whole hybrid. Such segment of PILs could not only promote the modification of polar PNIPAm onto the non-polar rGO by cation-π interaction, but also realize the immobilization of ferrocenecarboxylate anion (FcCOO−) via anion-exchange reaction. The PNIPAm moiety endowed the poly(NIPAm-b-BVIm[FcCOO])-rGO with thermal responsiveness, while the anion moiety provided additional electroactive function. It is noteworthy that the conformational change of PNIPAm segment upon different temperature could reveal or seal the redox probe of FcCOO−, thereby leading to a controllable expression of electroactivity switching by thermal stimuli. Owing to such regulation on surface property and conformation of PNIPAm segment, the modified electrode exhibited excellent thermally responsive electrocatalysis with reversible ‘ON-OFF’ effect toward the detection of ascorbic acid (AA), which led to two different catalytic states at the same electrode. The reversible electrocatalytic performance with switching capability of the poly(NIPAm-b-BVIm[FcCOO])-rGO/GCE is expected to have a broad application in the field of intelligent electrochemical sensors and devices.