Carbon nanotube reinforced poly(l-lactide) scaffolds: in vitro degradation, conductivity, mechanical and thermal properties

Poly(L-lactide (PLLA), nano-hydroxyapatite (nHA) and multi-walled carbon nanotube (MWCNTs) biodegradable scaffolds were produced through thermally induced phase separation (TIPS) and ultrasonically dispersed for use in tissue engineering. The results obtained showed that mechanical properties and conductivity improved with respect to the PLLA to which nanotubes had been added. Scaffolds with a nanotube weight of 1% and 5% showed the best properties, with a very uniform and well-arranged structure. The weight percentage of nanotubes is an essential parameter in determining the formation of agglomerates. Samples with a 10% carbon nanotube (CNT) weight showed aggregates, with the TIPS and ultra-sonication techniques found to be unsuitable for production with such high levels of reinforcement. The degradation process was modulated by morphology and not crystallinity, with the PLLA/nHA samples degrading more readily due to their smaller pores which did not allow degradation products to escape as easily, resulting in autocatalytic degradation. The addition of nanotubes had a significant impact on the dielectric properties of the samples, which ceased to be an insulator and became a conductor.