Thermoplastic elastomers with multi-walled carbon nanotubes: Influence of dispersion methods on morphology

PBT-block-PTMO thermoplastic elastomers derived from dimethyl terephthalate (DMT), 1,4-butanediol(BD) and poly(tetramethylene glycol) (PTMG) were synthesized in the presence of oxidized multi-walled carbon nanotubes (MWCNTs) by a two-stage process involving transesterification and in situ polycondensation. Two procedures were applied to nanotubes in the polymer matrices were used. In procedure 1, nanotubes were dispersed in DMT + BD before the transesterification, while in procedure 2 nanotubes were dispersed in PTMG after transesterification. The mole ratio of the starting components was selected to produce copolymers with a constant hard to soft segment weight ratio of 45:55. Characterization of the new nanocomposites was performed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), small- and wide-angle X-ray scattering (SAXS/WAXS). A better nanotube dispersion can be achieved when oxidized MWCNTs are added to the DMT + BD monomers before transesterification (procedure 1). Oxidized MWCNTs exhibit strong interfacial adhesion to the polymer matrix for both procedures.