Stimuli-responsive carbon nanotubes based on the interlinkage of carbon dots

The preparation of stimuli-responsive carbon nanotubes (CNTs) is often achieved through covalent connection between stimuli-responsive polymers and CNTs. However, pre-treatment of CNTs to achieve covalent bonding can disrupt the surface structure of CNTs, so as to reduce the electron delocalization of CNTs, thereby damaging its inherent optical and electronic properties. In this work, a simple and non-destructive method was demonstrated to construct various stimulus responsive CNTs by using a carbonous material, carbon dots (CDs), as joint part. CDs with large π bond can interact with non-polar carbon nanotubes (CNTs) through π-π interaction without causing damage to the surface of CNTs. The epoxy bond of modified CDs provides binding sites for polymer initiators 2,2′-azobis[2-methylpropionamide] dihydrochloride (AIBA). Based on this, stimuli-responsive polymers such as poly (N-isopropylacrylamide) (PNIPAm) or polyacrylic acid (PAA) can be loaded onto the CDs modified CNTs, thereby achieving the construction of stimulus responsive CNTs. When the temperature or pH switches, the surface water contact angle (WCAs) of CNTs/CDs-PNIPAm varies between high and low values because of the shrinkage and extension of PNIPAm and PAA chains. Such unique property can also lead to the utilization of CNTs/CDs-PNIPAm as an intelligent electrode material. The changes in the surface hydrophobicity of materials can regulate the contact of water-soluble electrochemical probes with modified electrode surfaces, thereby controlling the expression of electrochemical activity. The prepared modified electrodes exhibit reversible ’ON-OFF’ switching effect against temperature or pH changes. This non-destructive method for constructing stimuli-responsive CNTs holds great potential for applications in the field of intelligent electrochemical sensors and devices.