Abstract
We describe a novel and facile strategy to modify the surface of carbon nanotubes (CNTs) with two
chemically different polymer brushes utilizing the ‘grafting from’ technique. A [4 + 2] Diels–Alder
cycloaddition reaction was used to functionalize multi-walled carbon nanotubes (MWNTs) with two
different precursor initiators, one for ring opening polymerization (ROP) and one for atom transfer
radical polymerization (ATRP). The binary functionalized MWNTs were used for the simultaneous
surface initiated polymerizations of different monomers resulting in polymer grafted MWNTs that can
form Janus type structures under appropriate conditions. 1H NMR, FTIR and Raman spectra showed
that the precursor initiators were successfully synthesized and covalently attached on the CNT surface.
Thermogravimetric analysis (TGA) revealed that the grafted polymer content varies when different
monomer ratios and polymerization times are used. The presence of an organic layer around the CNTs
was observed through transmission electron microscopy (TEM). Differential scanning calorimetry
(DSC) proved that the glass transition (Tg) and melting (Tm) temperatures of the grafted polymers are
affected by the presence of the CNTs, while circular dichroism (CD) spectra indicated that the PLLA ahelix
conformation remains intact.