Hyperbranched Polymer Functionalized Carbon Dots with Multistimuli-Responsive Property

The pyrolysis of a hyperbranched polyethylenimine (PEI) and glycerol mixture under microwaves generated the carbon dot (CD) functionalized with PEI (CD-PEI). Isobutyric amide (IBAm) groups were attached to CD-PEI through the amidation reaction of isobutyric anhydride and the PEI moiety, which resulted in the thermoresponsive CD-PEI-IBAm's. CD-PEI-IBAm's were not only thermoresponsive but also responded to other stimuli, including inorganic salt, pH, and loaded organic guests. The cloud point temperature (T_cp) of the aqueous solutions of CD-PEI-IBAm's could be modulated in a broad range through changing the number of IBAm units of CD-PEI-IBAm or varying the type and concentration of the inorganic salts, pH, and loaded organic guests. All the obtained CD-PEI-IBAm's were photoluminescent, which could be influenced a little or negligibly by the added salts, pH, and the organic guests encapsulated.