Functionalization of carbon and gold nanomaterials using PNIPAAm grafted dextran: a general route towards robust and smart nanomaterials

A universal functionalization platform based on PNIPAAm grafted dextran smart polymers for, but not limited to, carbon and gold nanomaterials, is developed. The dextran based smart polymer contains three indispensable components: 1) dextran - to provide hydrophilicity and stability; 2) PNIPAAm - to provide stimuli-sensitivity; 3) dodecylthiocarbonothioylthio groups (or aminolysis-generated thiols) to provide feasible functionalization through stable interactions between polymer and nanomaterials. The readily accessible distinctive versions of polymers can provide necessary and efficient interactions with a variety of nanomaterials: the unique dodecyl end groups provide the effective functionalization of SWNT and NGO in a noncovalent manner, while the AuNR can be covalently functionalized through aminolysis-generated thiols. These functionalized nanomaterials are simultaneously endowed with well-retained properties of interest, excellent stability and smart properties: they exhibit superior stability under various conditions and the absorption, fluorescent and aggregation properties can be smartly tuned by temperature and NIR light. The establishment of this general approach is an important step forward for development and wide-application of smart nanomaterials in catalysts, actuators, sensors and biomedicine.