Synthesis and characterization of water-soluble multiwalled carbon nanotubes grafted by athermoresponsive polymer

Abstract

Water-soluble multiwalled carbon nanotubes (MWNTs) withtemperature-responsive shells were successfully prepared by grafting poly(N-isopropylacrylamide) (PNIPAM) from the sidewalls of MWNTs, via surface reversibleaddition–fragmentation chain transfer (RAFT) polymerization using RAFT agentfunctionalized MWNTs as the chain transfer agent. Thermogravimetric analysis (TGA)measurements showed that the weight composition of the as-grown PNIPAM polymers onthe MWNTs can be well controlled by the feed ratio (in weight) of NIPAM to RAFT agentfunctionalized MWNTs (MWNT-SC(S)Ph). The MWNT-g-PNIPAM has good solubility inwater, chloroform, and tetrahydrofuran (THF). Transmission electron microscope (TEM)and scanning electron microscope (SEM) images also showed that the MWNT-g-PNIPAMwas dispersed individually and eventually bonded with the polymer layer by surface RAFTpolymerization. The PNIPAM shell is very sensitive to a change of temperature. Thismethod could find potential applications by grafting other functional polymer chains ontoMWNTs.